McQUav” Installation andMaintenance Data

MicroTech’”Unit Controller

CONTENTS

I N T R O D U C T I O NG e n e r a l D e s c r i p t i o n

P a n e l H a r d w a r e .Vacuum Fluoresent DisplayR e s e t C o n t r o l O p t i o n s .

33455

INSTALLATIONFac to ry Moun ted & W i red 6I n t e r c o n n e c t i n g W i r i n g 6S t a r t e r T y p e 7Starter Overload Relay Contacts 8C o n v e n t i o n a l O v e r l o a d s 8Mu l t ip le S ta r te r Res is to rs 8Chilled Water Pump Control 8A l a r m R e l a y . 9Cooling Tower Fan Control 9Lead/Lag Load Balance or CPC 10W i r i n g . 10R e m o t e R e s e t C o n t r o l 10

STARTING THE UNITI n i t i a l S t a r t - u p C h e c k s . 18H e x a d e c i m a l S w i t c h e s 18Mechanical Protective Switch Settings 19Dry Running the Contro l Panel 19Starting the Centrifugal Compressor 20

OPERATIONO p e r a t i n g S e q u e n c e .22T e m p e r a t u r e C o n t r o l O p e r a t i o n . :22, 23Software Version Number Code Information 23O i l T e m p e r a t u r e . 24The Keypad . . . ..__............._._.. 25T o C h a n g e a Setpoint 25P a s s w o r d I n f o r m a t i o n 25W a t e r T e m p s K e y p a d 26Softload K e y p a d .._..........._ 26C l o c k S c h e d u l e K e y p a d 27O v e r r i d e C o n t r o l 27M a n u a l V a n e C o n t r o l 27

F a u l t H i s t o r y - C l e a r F a u l t . 27S e t - u p O p t i o n s 28Time Control Functions (Not Clock Schedule) 28

S t a r t - t o - S t a r t / S t o p - t o - S t a r t 28Oil Pump is On/Post Lube (Oil Pump) 28C o n d e n s e r P u m p T i m e r 28Ent. Evap. Timer . . 29Delay Timer . 29L o a d D e l a y ( W a i t i n g f o r L o a d ) 29MCR i s On (o r S top , Un load ing ) 29O v e r r i d e ( H R S ) 29S o f t L o a d ( R a m p U p T i m e ) 29S t e p a n d W a i t 29

OPERATION LEAD-LAG/LOAD BALANCE PANELGeneral ..__.___. _.

Lead-Lag . . . . ..______.....___.__..L a g S t a r t - S t o p

A u t o m a t i c S t a r t - u p .Load Balance . . . ..__._____..._.__.._..K e y D i s p l a y S e c t i o nKey Setpoints Section .K e y S e r v i c e S e c t i o nK e y S e t - u p O p t i o n sK e y C l o c k S c h e d u l eK e y S e r v i c e S e t p o i n t .

2929292929303031313233

SERVICEProtective Control Time Constraints.S i g n a l C o n v e r t e rW a t c h d o g P r o t e c t i o nO i l G a u g e T r a n s d u c e r .Sensors . .S o l i d - s t a t e R e l a y T e s t i n gT r o u b l e S y m p t o m C h a r t .Test Procedure-Trouble AnalysisMicroTech P a n e l L a y o u tO p e r a t i n g L o g R e c o r dWarranty

3 53 5 _3 53 63 63 8

k, .39 414 24 34 4

CAUTION

Connections and service to this panel must only be provided by personnelknowledgeable in the operation of the equipment being controlled. Ignorance orcarelessness can cause personal injury or equipment damage.

The word “EnGinn” or “ENGINN” used in this publication is a copyrighted trademark of EnergyLIne Systems L.P. and is used with permission.

“MicroTech” IS a trademark of SnyderGeneral Corporation, Minneapolis, MN.

01994 SnyderGeneral Corporation. All rights reserved throughout the world.

Page 2 I IM 403

INTRODUCTION

The following pages provide information on the features, in-stallation, operation and problem analysis of the McQuayMicroprocessor control for Centrifugal chillers.

Some discrepancy may exist between display statements,

or time Intervals on certain units, and published data. Thedifferences are minor and exist because of SnyderGeneral’savowed ntention to continually improve its products.

Figure 1. MicroTech Control Panel

-

GENERAL DESCRIPTION

The MicroTech Unit Controller is a microprocessor based con-trol panel designed to initiate the step-by-step start functionsof its host centrifugal compressor unit, monitor and regulatethe compressor’s capacity, protect it, and sequence the com-pressor shutdown on temperature demand or in response toa pre-set time.

Visual display of the entire sequence of functions is pro-vided in plain English on a 20 character vacuum fluorescentdisplay.

Communication ports permit control and/or status inquirythrough a telephone modem, or over a limited distance,through a twisted pair, to an IBM PC compatible computer

using MIcroTech software.In the event the compressors’ operation is interrupted by

the action of a safety trip, the cause of the trip condition isdisplayed. To further assist the operator or service person-nel, the cause of the preceeding eight trip conditions is alsorecorded in the non-volatile memory.

Information about the units’ fault history, setpoints oroperating display values may be obtained by pressing anyof 24 touch sensitive membrane key switches.

To protect the system from unauthorized or accidental set-point changes, the MicroTech panel also includes operatorpassword protection.

IM 403 / Page 3

Power Cartridge (Input/Output)

I Mother BoardOil PumpContactor \

FieldConnection

TerminalStrip

/ // f Daughter Board

TR-3 (Top) -/ TR-2 -. \

- SurgeguardGuardistorRelays

- MechanicalHigh Press. (Left)and Low Press.

cutouts

- DisplayEnGinn

T&lTransformers AC to DC volts

Signal Converter

- Solid-stateOutput Relaysand Mounting Board

The control panel contains the following components:

0 16 lighted and fused optically isolated output contact ter-minals for pre-assigned logic control functions.

See the Control Legend or the wiring schematic for specificterminal identification.

0 14 analog and 12 digital information inputs. The monitoreddata includes water and refrigerant temperatures, motoramperage, oil pressure and oil temperature.

0 Digital contact closures prove the existence or operationof ancillary functions required for the safe operation of thecontrolled chiller.

(For a complete list of inputs, see the table provided or thewiring schematic).

0 Microprocessor Control EnGinn parts consisting of durablealuminum encased logic and power (l/O) cartridges secure-ly clamped to the controller mother board.

0 A daughter board to collect and condition digital andanalog input signals, and deliver the needed voltage levelsto the microprocessor.

0 An aluminum encased 20 character microprocessordisplay EnGinn.

0 A printed circuit AC to DC signal converter. (Optional).

0 Three 115 volt to 24 and 12 volt control power transformers.

0 Compressor Surgegard and motor Guardistor protectiverelays and capacitors.

l Mechanical/Electrical low pressure (MLP) and highpressure (MHP) refrigerant protective controls.

0 A Safety fault Trip Relay (FT).

l Oil pump contactor with auxiliary interlocks

0 Communication ports.

0 An internal 115 volt, 3 amp manual reset circuit breaker.

0 An electrically grounded, touch sensitive keyboardmounted on the cover panel.

0 A cover panel mounted “Stop-Auto” switch.

0 Cover panel mounted indicating lights for indicating thestatus of the microprocessor control and compressorloading or unloading.

Page 4 I IM 403

VACUUM FLUORESCENT DISPLAYThe display type used was carefully selected for its clarity and

The other four (4) reset options require an external 4 to 20

long life. The system is equipped however to automaticallymA signal, input to the field connection terminals 69, 70, and

shut off the display if keypads have not been pressed within71. The 4 to 20 milliamp transmitter will itself be controlled

the preceeding ten minutes.by a demand limiter for motor current limit, or for chilled waterelevation based upon an EMS control.

RESET CONTROL OPTIONSThe MicroTech panel is programmed to accept:

No Reset.. .Reset ; NoneEnter ing Chi l led Water . Reset = ENTLeav ing Ch i l l ed Wate r . Rese t = ChWElectrical Demand. .Reset = AMPElectrical Demand & ENT. Reset = AMP ENTElectrical Demand & ChW. Reset = AMP CHW

If the Installation consists of multiple chillers, or a singledual compressor chiller, with a lead-lag/load balance (LLLB)control, the remote reset transmitters are connected to thelead-lag control panel, not to the individual MicroTech panels.The control signal is then sent to the individual chiller throughthe LLLB. See the field connection wiring diagram for theLLLB accessory panel.

Figure 3. Keypad and Display.

If entering chilled water is elected as a reset option, no ad-ditional control is required. The MicroTech panel will attemptto control a fixed return water temperature. To do so, as thebuilding load is reduced, return water temperature willdecrease. The microprocessor, however, wilt check returnwater temperature every 2 to 60 minutes (operator adjustable)and elevate the leaving chilled water temperature to regainthe original return water (entering water) temperature.

Since the “Start” and “Stop” temperatures are temperaturedifferences from the leaving chilled water setpointtemperature, the actual “start” and “stop” temperatures alsoreset as the leaving chilled water temperature is reset.

As building load is increased, the return water temperaturewould increase, causing the microprocessor to lower leavingchilled temperature, thereby returning the return chilled watertemperature to its original value.

Figure 4. Max. Chilled Water Reset

MAXIMUMCHILLED WATERRESET

ZERCR E S E T -

- ADJUSTABLE UP TO 15 F MAX

/

A C T U A L mA I N P U TC A I . C U L A T E S T H EAMOUNT OF RESETBASED ON MAXIMUMDESIRED AT 20 mA

i mA-DC

REMOTE RESET INPUT SIGNAL

20

Fi

I

gure 5. Percent Max. Amp Limit.

% MAXIMUMA M P L IMIT

%REMC E

AMPLIMIT

/I

/

+,/

I,/ ‘I/”

4 mA-DC 20

REMOTE RESET INPUT SIGNAL

IM 403 I Page 5

FACTORY MOUNTED & WIREDMicroTech panels are completely factory assembled tested andmounted on centrifugal chillers. Sensors are located as shownin Figure 6 and are pre-wired with shielded cable to their ap-propriate termination. Field wiring connections need only bemade to the terminal strip located on the left side of the con-trol panel.

The following provides general wiring information of interestfor service, and for those installations where the control panelwill be retrofit to an existing installation.

INTERCONNECTING WIRINGInterconnecting wiring to the MicroTech control panel consistsof:l Sensor wiring to the analog input terminals.

l 24 volt wiring to the compressor motor starter (field installedif a remote starter is used), and to chilled water and con-denser water flow switches and interlocks, alarm relay andexternal cycling or reset control.

interlocks, flow swit-be dry contactsVAC control cir-AC CONTROL

POWERR INTOFurther, care must be exercised in routing these interlock

lines. They must not be sufficiently long to produce avoltage drop, and they must not be run in conduit with highvoltage lines.

l 115 volt wiring to the compressor motor starter MCR coilcircuits, to the control power source, and to condenserwater pump and chilled water pump relay coils. 115 voltwiring is also required if relays are used to stage coolingtower fan operation. Two stages of tower control are possi-ble. (See subsection “Cooling Tower Fan Control”).

l Communications wiring.

A typical field wiring diagram is shown (Dwg. No. 706107C-01).Wire and components used must comply with the following:1. Sensor wires must be shielded cable and must be ground-

ed only at the MicroTech terminal strip end.

2. 24 volt wiring must be AWG No. 18 or larger dependingupon length of run, and must be installed as NEC ClassI wiring system, but must be run in a separate conduit from115 volt or higher voltage wiring.

3. 115 volt wiring shall be AWG No. 12 or larger size depen-ding upon length of run. Maximum voltage drop shall be3%. This maximum voltage drop shall be considered inconjunction with the length of run in the determination ofwire size. (See McQuay SVT-WS).

Transmitter wires providing a reset signal based uponchiller water temperature or motor current should be runin a separate conduit.

Communications wiring shall be standard insulatedtelephone wire, for telephone modem communication. Inall other cases, use shielded twisted pair similar to Belden#8760. For complex communication and control systemssee the wiring recommendations in other appropriatepublications.

A Hayes or compatible modem with its own 115 volt powersupply is required if phone communication will be used.Baud rate required is 1200. Communications interface shallbe RS232. If direct, hardwired communication will be us-ed, a dedicated, shielded twisted wire pair may be extend-ed to not more than 50 feet. Where hardwired communica-tions of over 100 feet will be required, an extended rangekit is recommended (McQuay part number 654870B-01).

Miscellaneous chilled water pump, condenser water pump,cooling tower fan motor control relays and an alarm relayare normally field supplied. These relays require either 115volt or 24 volt coil, and are limited to a 25 VA maximumpower consumption, per coil. (See Table 8 and theschematic wiring diagram).

A 0 to 7 volt AC, to 0 to 4 volt DC signal converter, or 4to 20 mA, DC load signal is required at the customer fur-nished starter; or a separate factory mounted signal con-verter will be supplied if required.

If the customer will furnish a 0 to 20 milliamp signal to fieldconnection terminals numbered 1 and 2 in lieu of a 0 to 5volt AC signal, then a 249 ohm resistor, &lo/o, 1/4 watt mustbe connected across terminals 9 and 10 on the TS4 terminalstrip. In addition, the transmitter must be capable of span ad-justment to permit a final resolution of the peak control signalfor 100% amps display on the MicroTech panel.

The optional factory supplied signal converter will accepta 0 to 7 volt AC signal. If the starter’s current transformer andresistor circuit supplying this voltage is grounded, the groundmust be connected to the side of the control circuit connectedto the terminal 2 in the MicroTech panel Field Connection ter-minal strip.

Terminal strip TS1 used to connect field interlock wiringto the daughter board, will be disconnected at the daughterboard prior to shipment. A qualified start-up technician, us-ing an accurate voltmeter, and with interlock contacts closed,should read the voltage at each socket of the terminal stripTS1 before reconnecting the terminal strip to the daughterboard. Voltage between each socket and terminal G shouldread approximately 24 volts AC. Following this verification,and with the power disconnected to the panel the TS1 ter-minal may be connected as shown in Fi’gure 15.

Figure 6. Analog Sensor Locations. (See Table 3 for Component Descriptions).

Page 6 / IM 403

Wiring Notes1.

2.

3.

4.

5.

Compressor motor starters are either factory mounted and wiredor shipped separate for field mounting and wiring. If provided byothers, starters must comply with McQuay specification 359A999or 7515A69. All line and load side power conductors must becopper.

If starters are free standing then field wiring between the starterand the control panel is required. Minimum wire size for 115VAC is 12 GA. for a maximum length of 50 feet. If greater than50 feet refer to McQuay for recommended wire size. Wire sizefor 24V AC is 18 GA. All wiring to be installed as NEC Class Iwiring system. All 24V AC wiring must be run in separate con-duit from 115V AC wiring.

Optional reset of chilled water temperature or reset of motor cur-rent limit can be accomplished by wiring 4-20 MA DC as shown.If customer supplied transmitter does not have a power supply,then a 17V DC unregulated power supply can be obtained at ter-minal X67 of the control panel. It is recommended that transmit-ter wires be run separately from the 115V AC wiring.

An optional customer supplied 24V AC, 25 VA maximum ratedalarm relay can be wired as shown. The circuit will be de-energized if any safety shutdown occurs.

Remote ON/OFF control of units for multiple unit applications canbe accomplished by installing a set of dry contacts between ter-minals 9 and 64. If an additional point of ON/OFF control is re-

quired. remove jumper J6 from terminals 64 and 65 and installthe additional set of dry contacts.

6. Evaporator and condenser water pressure differential or pad-dle type flow switches are required and must be wired as shown.If field supplied pressure differential switches are used thenthese must be installed across the vessel and not the pump.

7. Oil cooler solenoid valve (ASCO) model -8210827 is requiredon some models. If not factory installed, refer to the installa-tion manual and wire as shown.

8. An optional customer supplied 115V AC maximum coil ratedchilled water pump relay (CHWR) may be wired as shown. Thisoption will cycle the chilled water pump in response to buildingload

9 The condenser water pump must cycle with the unit. A customersupplied 115V AC, 25VA maximum coil rated condenser waterpump relay (CWR) is to be wired as shown.

10. Optional customer supplied 115V AC, 25 VA maximum coil ratedcooling tower fan relays (Cl, C2) may be wired as shown. Thisoption will cycle the cooling tower fans in order to maintain unithead pressure.

11. Auxilliary 24V AC rated contacts in both the chilled water andcondenser water pump starters must be wired as shown.ALL WIRING to be NEC Class 1.

STARTER TYPEMcQuay Centrifugal chillers are primarily designed for usewith Star-Delta and auto-transformer starters requiring a tran-

no transition takes place. In this event (i.e., there is no transi-

sition between starting stages.tion in the starter), it is necessary that a normally open aux-

They can also be used with across-the-line starters whereillary contact on the starter be wired between control panelterminals numbered 11 and 12.

IM 403 I Page 7

STARTER OVERLOAD RELAY CONTACTSThe MicroTech control panel is designed to accept an overloadtrip action from a conventional thermal or magnetic overload;or from a solid state device similar to the McQuay IQ-1000.

If an IQ-1000 or similar solid-state overload is used, the nor-mally closed overload trip contacts are wired in series withthe MCR (Main Contactor Relay) coils.

An additional set of trip relay contacts on the solid stateoverload are wired between the MicroTech control panel ter-minals 6 and 22. These terminals should be the type that areclosed whenever control power is applied to the overloaddevice, and open when:1. Power to the device is interruped or2. An overload trip occurs

When this overload relay trips, the control panel display willindicate a “Starter Fault”.

IQ-1000 contacts to be wired in series with MicroTech ter-minals number 6 and 22 are terminal numbers 15 and 16.

CONVENTIONAL OVERLOADSIn the event the overloads used with the MicroTech panel areconventional thermal, or magnetic, their normally closed con-tacts should be wired in series with the MCR coil(s). Sincethere is no second, parallel, set of contacts to be wired acrossterminals numbered 6 and 22 on the MicroTech panel, ajumper must be connected between these terminals.

Operation of the overload trip is displayed under this con-dition by the message “Starter Transition”. This display oc-curs because the auxillary starter contact wired betweenMicroTech terminals number 11 and 12 will open, with anoverload signaling the shutdown.

MULTIPLE STARTER RESISTORS(Use of Terminals 2 and 2A)Many installed starters are equipped with two resistors in thecurrent transformer’s circuit. These are identified as resistorA and resistor B. The second resistor, resistor B was requiredfor the McQuay resistance type load balance. With MicroTech’slead-lag/load balance accessory control, the B resistor is notrequired and can be deleted from the circuit simply by ad-ding a jumper between terminals 2 and 2A.

CHILLED WATER PUMP CONTROLThe MicroTech control panel has been designed to permit thechiller control panel to initiate the starting and stopping of thechilled water pump in response to a call for the chiller’soperation.

This feature may or may not be used, at the option of thesystem designer.

If it is not used, that is, if the system is designed such thatthe chilled water pump is started by a remote time clock, orseparate manual pushbutton station,1. A chilled water relay need not be installed between con-

trol panel terminals number 36 and 44 an shown in wiringdiagrams numbered 706308D.

2. Interlock connections such as a flow switch, or water dif-ferential pressure switch , and pump starter interlock con-nections must be wired between control panel terminalsnumbered 10, 62 and 63.

3. If the chilled water pump’s “On” and “Off” operation willbe the primary control signal to start and stop the chiller,the following hardware and control sequence are recom-mended to protect the chiller from damage and eliminateany possibility of nuisance safety trips. (See Figure 9).a. Install a chilled water flow switch or differential pressure

switch and a chilled water pump starter interlock in theprotective circuit provided (between terminals 10, 62 and63).

Page 8 / IM 403

Follow the guidelines recommended in paragraph 4concerning wiring for the flow switch and interlockcircuit.Install a normally open contact from the time clock orEMCS to the 24 volt AC remote switch circuit of theMicroTech panel. Wire these contacts between terminals9 and 64 on the MicroTech field terminal strip.Be sure to program the set-up options key for “Remote”control as described under the keypad functions.The time clock control must be another normally clos-ed set of contacts. These are required to start the chill-ed water pump by closing a contact in the circuit to thepump contactor coil (PC), and to close a circuit to aninstant on (IOT) or a solid-state timer (SSTD) as shown.See the applicable proposed wiring diagram.These devices work in the following manner:When the time clock or EMS control calls for the airconditioning system to operate, it will complete the elec-trical circuit to the chilled water pump contactor, andto the chiller’s remote starting switch.

The chilled water pump will start immediately, clos-ing flow switches and interlocks in the chiller’s protec-tive circuit. Concurrently, closure of the remote(MicroTech) contact circuit will begin the normal chillerstarting sequence.

As the time clock, or EMS is satisfied, it will open itsnormally open contacts, and will close the normally clos-ed contacts in series with the IOT or SSTD coil circuit.IOT, or SSTD contacts in parallel with the normally openTC contact in the pump contactor coil circuit will closeinstantly, keeping the pump energized for 3 to 4 seconds(the minimum time delay recommended) after theMicroTech’s remote control circuit has been opened.

In this manner, the chiller will cycle through a nor-mal controlled shutdown without tripping on chilledwater pump safety controls.At the same time, water flow switches are operable asprotective controls should the need arise.

4. Interlock wiring must NOT be connected to a separatevoltage source outside of the MicroTech panel. Internally,one side of the connection (terminal No. 10) is connectedto + 24 volts AC. Further, if the wiring will be of a very longrun, creating excessive voltage drop or will run in conduitwith other, high voltage wiring causing induced currentflow, a separate relay and contact circuit may be required.(See Figure 8).

Figure 8. Alternate Interlock Wiring. (For long runs for systemswhere voltage might otherwise be induced).

I_ 7y-‘--ro1’ON MICROTECH

d

If the MicroTech panel will be used to start and stop thechilled water pump, the system designer should be awarethat the pump will routinely cycle off only with an interruptionin the switch, time clock, or protection, circuit. The pump willnot cycle off when the controlling chilled water thermostat issatisfied.

If this action is not desirable because the controlled pumpis the principal system pump, the alarm relay circuit may beused with a normally closed contact to provide a parallel con-tact in the pump’s control circuit.

Should this latter wiring be considered provision must bemade to open this circuit during scheduled downtimes.

lure 9. Wiring Schematics.

PC

ccr’”

REMOTE SWITCH

TC

I I 0

9 64

L

24V AC h

.t--

‘iL_ 24:.21C i.

TC .llrne C lock

PC - Pump Control

IOT Instant ON Timer(3 to 4 sec )

ALARM RELAY(See Table 1 for Relay Coil Characteristics)Provision exists on the MicroTech control panel to activate analarm circuit whenever a fault occurs.

The 24 volt alarm relay (field supplied) is normally energizedwhenever 120 volt control power is applied to control panelterminals number Ll and L2 and the 3 amp circuit breakeris closed.

If a fault occurs, preventing the chiller from operating, andthe fault is recorded by the MicroTech control, the alarm relaycircuit will open, de-energizing the relay.

Normally closed relay contacts should be used in a separatecircuit to annunciate the fault.NOTE: If an alarm relay is used, we suggest that the annun-ciation circuit include a service ‘interruption’ switch to pre-vent unnecessarily triggering an alarm during normal serviceoperations.

Table 1. Customer Furnished A.C. Operating Relays.

A 24 1 N.C. 1 Optional 1

* No single co11 with a rating of more than 25 VA may be connected. Maximum total VArating of field supplied coils shall not exceed 125 VA.

COOLING TOWER FAN CONTROLThe MicroTech panel includes software capability to start andstop two stages of cooling tower fans in response to differen-tial refrigerant pressure.

The system offered provides a form of head pressure con-trol. If it will be used, the installer must provide one or two115 volt coil relays to be wired as shown in the field wiringdiagram. See Table 1 for relay characteristics.The field supplied relay(s) will be energized as required bythe operating compressor’s refrigerant pressure differentialthrough the factory mounted solid-state relays. These latterrelays will energize and de-energize based upon the settingsprogrammed for them under the set-up options keypad.

Contacts from the installer furnished relays will be impos-ed in the starting circuit for the tower fan(s) contactor coil.

The MicroTech design is such that one or both of the towerfan control relays may be omitted, and tower fan control fur-nished in another manner.

The installer should also note that tower fan cycling by itselfmay not be adequate to prevent lower than desirable refrig-erant condensing pressure. If the building load, tower and fansize or arrangement, and ambient wet bulb temperature com-bine to require adjustments in water flow in the condenserwater system, the engineer or installer should provide thatpiping and control.

IM 403 / Page 9

LEAD-LAG/LOAD BALANCE (LLLB)The lead-lag/load balance (LLLB) control is a special purposecomputer. It is designed to interact with two separateMicroTech unit panels for maximum control efficiency. Througha simple twisted pair wiring connection between the wall, orunit mounted, controller, and two MicroTech unit panels, thecomputer designates the lead chiller, directs the lag machineto start and stop in response to pre-determined operating con-ditions, and causes the machines to operate at approximate-ly equal percent of RLA when both units are operating.

Since the LLLB controller has no display or keypad, theprimary start/stop protective control functions remains witheach individual MicroTech unit panel. For this reason, eachMicroTech unit panel must be programmed entirely; and atequal values of temperature, reset and clock scheduling. Thesingle difference between the two MicroTech unit controlpanels should be the hex switch settings of the DisplayEnGinn. Set all hex switches according to the values shownin Table 11.

Whether or not the clock schedule will be used to controldaily or weekly operating hours, the clock schedule MUSTbe activiated on each chiller if the lead-lag/load balance ac-cessory is expected to work. The clock schedule is activiatedby pressing the “Clock Schedule” keypad 10 times, then set-ting the display "S1 First Day = Sun” (or Mon. etc). This set-ting must NOT read “=OFF”. With the clock schedule ac-tiviated, it will be desirable to check the holiday settings tobe sure the units will run on all of the davs intended. If no

date at “0", “0”. For more information see the keypad sec-tion covering the “Clock Schedule”.

Dual compressor units shipped from the factory have theclock schedule S1 First Day=Sun.

For more detailed information on the LLLB control panel,see IM 425.

WIRINGThe contractor will mount the LLLB control panel within sightof the chillers in a reasonably accessible location. A sourceof 115 volt AC control power must be connected to terminalsL1 and L2 inside the LLLB box. Wiring must be sized to carrynot less than 5 amps. Shielded twisted pair wiring of 22 AWGminimum should be connected between the remote controllerand communications port B of the Display EnGinn on eachMIcroTech panel.

See the appropriate field connection wiring diagram forspecific details.

On dual compressor PFH units, the panel may be factorymounted and the wiring complete.

REMOTE RESET CONTROLIn the event remote reset of chilled water and/or electrical de-mand will be provided, the customer furnished 4 to 20 mAtransmitter(s) and wiring must be connected to the LLLB box,and not to individual MicroTech unit panels. The “Set-up Op-tions” key for each MicroTech panel must, however, reflect the

holiday shut-off dates are wanted, set the holiday month and reset opt-ions(s) chosen.

Figure 10. Lead-Lag Wiring Diagram.

N O T E I

: IL E A D / L A G 00X

r - - - - - - - - l----_ ___ _____-_-- 1

II I

CONTROLLER .I

LEGENDIDENTIFIED TERMINAL; 1

: L____--______-_____ 4 _ 20 MA ,NPUT FOR

t____________________ REMOTE DEM4ND LIMIT

NOTES:I. ON PFH UNITS. 115 VOLT POWER WIRING AND COMMUNICATION WIRING IS FAClORY

INSTALLED. ON FIELD INSTALLED UNITS. II5 VOLT AC POWER MUST BE PROVIDED(MAXIMUM 5 AMPS).

2. ;;~~,~,lC4TION CABLE MUST BE TWISTED PAIR OR SHIELDED CABLE iMINIMUM

3. ADAPTER CABLE PROVIDED llTn FIELD MOUNTED LEAD/LAG BOX.

. UNIDENTIFIED TERMINAL-,=+ FACTORY SUPPLIEDGt CONDUCTOR SHIELGED._: CABLE - 22 GA. MIN.

-+-b-FIELD SU?PLIED_:_;_Z CONDbCTOR SHIELDED

1 CAELE - 22 GA. MIN.._

-FACTOR.r WIRING-----FIELD WIRiNG

Page 10 I IM 403

00a”” 1

001 a

06

05

Table 3. Control Devices

1~ Analog~~ ~ 1 TS4-03/04 1 On the oil line leaving the oil cooler & entering the compressor.1 TS4-05/06 1 Strapped to, or in a well in the oil pump below the oil level.

From a pressure to electric signal transducer located on the back of the

Table 4.

Digital

TSl -06(A)

TSl-1 l(S)

Mounted in the front MicroTech cover Must be closed to start &

panel. run.

Remote (Optional) switch, may be locatedClosed to start & run.^^.^.,lr^_^

Digital TSI-06(S)Differential or flow switch in the cond.

Closed to start & run.I

r flow switch in the chilledClosed to start & run.

..,I-TIT ~~~ Switch IS mounted in the compr. lube Must be closed to start,TSl-12(B)

box. can be open during run.

IM 403 I Page 11

Figure 12. Typical Schematic Wiring (Dwg. No. 706306D-01, Rev. OP)

3wI-7_-n,--_z__-ii-2.--

ii-

G---ii--a-ii--w---so---51---

70--1.---ii

? z-15--__so----95-

Page 12 I IM

Figure 13. Legend-Symbols and Wiring Schematic Notes (Dwg. No. 706105C-01)

_ _

LEGENDA . ..........................ALARM, RELAY COIL

CAP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CAPACITOR

Cl3 . . . . . . . . . . . . . . . . . . . . . . . . . . . CIRCUIT BREAKER

CHW . . . . . . . . . . . . . . . . . . . . . EVAPORATOR FLOW SWITCH

CHWI . . . . . . . . . . . . . . . . . . EVAPORATOR WATER INTERLOCKS

CHWR . . . . . . . . . . . . . . . . . . . EVAPORATOR WATER RELAY

CW. . . . . . . . . . . . . . . . . . . . . . .CONDENSER FLOW SWITCH

CWI. . . . . . . . . . . . . . . . . . .CONDENSER WATER INTERLOCKS

CWR . . . . . . . . . . . . . . . . . . . .COND. PUMP CYCLING RELAY

Cl . . . . . . . . . . . . . . . COOLING TOWER FAN RELAY (STAGE 1)

C2 . . . . . . . . . . . . . . COOLING TOWER FAN RELAY (STAGE 1)

G . . . . . . . . . . . . . . . . . . . . . . . . LIGHT (GREEN). MICRO STATUS

FT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FAULT RELAY

GD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUARDISTOR RELAY

HG . . . . . . . . . . . . . . . . . . . . . . . . . . . . HOT GAS SOLENOID

HP . . . . . . . . . . . . . . . . . . . . . . . . . . HIGH PRESSURE RELAY

LI . . . . . . . . . . . . . . . . . . . . . . . . . LIQUID INJECTION SOLENOID

MHP . . . . . . . . . . . . . . MECHANICAL HIGH PRESSURE SWITCH

MLP . . . . . . . . . . . . . . . MECHANICAL LOW PRESSURE SWITCH

M, . . . . . . . . . . . . . . . . . . . . . . . . . . . . CONTACTOR AUXILIARY

MCR . . . . . . . . . . . . . . . . . . MTR. CONTR. RELAY (STARTER)

OC. . . . . . . . . . . . . . . . . . . . . . . . .OIL COOLER SOLENOID

OD . . . . . . . . . . . . . . . . . . . . . . OIL PRESS. DIFFERENTIAL SW.

OL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OVERLOAD

OP. . . . . . . . . . . . . . . . . . . . . . . . . . . OIL PUMP CONTACTOR

OGT . . . . . . . . . . . . . . . . OIL GAUGE PRESSURE TRANSDUCER

PT ................ PNEUMATIC PRESSURE TRANSDUCER

R. ...... ....................LIGHT (RED). UNLOAD

SA.SB .................... VANE CONTROL SOLENOIDS

SG. ......................... .... SURGEGUARD RELAY

SW1 ......................PANEL START/STOP SWITCH

SW2 ....................... REMOTE START/STOP SWITCH

NOTES:1.

2.

3.

4.

5.

6.

7._~ 8.

9.

A separate 115 V * 10% 60 HZ, 115 V +5% -10% 50 HZ single phase 10. Voltage relay (VR) is used on units employing a CEO50 compressor. Onpower supply is required. Fuse size requirement IS 20 amp fusetron on the remaining units VR leads 404 and 405 are deleted and lead 403 isLl only. L2 is a grounded neutral. routed from terminal W to the capacitor.

A customer furnished 24 volt alarm relay coil may be connected betweenterminals 50 and 68 of the control panel. The alarm coil will de-energizewhen safety shut down occurs. Maximum rating of the alarm relay coilis 25 VA.

11. A customer supplied 4-20 MA signal can be supplied for chilled watertemperature reset or motor current limit reset. If the customer suppliedsignal requires a power supply, then a 17 VDC unregulated power supp-ly is available at terminal 67.

The compressor motor starters may be free standing or factory mounted.If factory mounted, all the control wiring between the starter and the con-trol panel is factory wired.

Oil cooler solenoid is a factory mstalled option on some models. If fieldsupplied it must be wired to terminals B and R located in the lube con-trol box.

12. A signal converter is supplied on units where the starter is not furnishedwith a O-5 VDC or 4-20 MA DC load signal. If signal is available thensignal converter leads 617 and 616 are deleted and lead 521 is routedfrom terminal 1 to TS4-9 and lead 522 is routed from terminal 2 toTS4-10.

Remote ON/OFF control of units for multiple unit applications can be ac-complished by installing a set of dry contacts between terminals 9 and64. If an additional point or ON/OFF control is required, remove jumperJ6 from terminal 64 and 65 and install the additional set of dry contacts.

Condenser water pump must cycle with the compressor by connectinga 115V relay coil (CWR) with a maximum rating of 25 VA between ter-minals 35 and 44.

13. Water flow protection for both the evaporator and condenser must be pro-vided. This protection shall consist of a flow switch or differential pressureswitch wired between terminals 10 and 62 for the evaporator, and 10 and60 for the condenser. In addition each pump starter shall have a set ofauxillary contacts wired to the following terminals (Evap.-Terminals 62 and63: Condenser-Terminals 60 and 61).

Three or four thermtstors may be used depending on motor size and type.

Surgeguard relay is not used on units employing a CEO50 compressor.On these units lead 614 is routed directly from guardistor relay terminal1 to TSi-1.

Liquid injection solenoid (Ll) and hot gas solenoid (HG) are found onlyon units supplied with these options.

14. A customer furnished 115 V evaporator water pump relay (CHWR) maybe connected between terminals 36 and 44. This relay will energizeanytime the control requires the evaporator water pump to be energiz-ed. The maximum rating of this coil is 25 VA.

15. Condenser water temperature control can be obtained by connecting twocustomer furnished staging relays between terminals 39 and 45 for thefirst stage and 38 and 45 for the second stage. The maximum rating ofthese coils is 25 VA.

TR-1. TR-2. TR.3 .............. TRANSFORMER (24 VAC CT)

TSl. TS2. TS3. TS4. .............. DAUGHTERBOARD CONN.

TO

v c

VR

Y .

%

2

0a

0

+

3

TIMED OPEN CONTACTS

VANE CLOSE SWITCH

VOLTAGE RELAY

LIGHT (YELLOW). LOAD

TERMINAL SYMBOLS

CONTROL BOX TERM. FACTORY WIRING

CONTROL BOX FIELD CONN. TERM.

LUBE BOX TERMINAL

STARTER TERMINAL

LEAD/LAG TERMINAL

UNIDENTIFIED TERMINALS

IDENTIFIED TERMINALS

AUTOMATIC RESET

MANUAL RESET

THERMISTOR

FACTORY WIRING

- - - - - F I E L D W I R I N G

- - - STARTER WIRING

--- - OPTIONAL WIRING

__H_ CABLE-TWISTED. SHIELDED_tf_ AND JACKETED PAIR

IM 403 / Page 13

Table 6. Field Connection Terminal Strip

0 24 VAC N Lube Box (O.D. SW) Corn-Term OP Aux. Contact

24 VAC N Term 78 Lube Box (O.D. & VC SW)

I,--’ 24 VAC N MHP & MLP & Lube Box (O.D. SW) Fault Relay Coil

?ouard Sensor Suraeauard Relav Coil

24 VAC Y Starter Fault Safety Trip 1 TSl-7 I

--------------------/ Alarm Bell Relay Co11

1 TSI-10

1 Starter 2 MA Aux.

24 VAC Y Terminal 58

24 VAC Y’ Terminal 58L 24 VAC Y Terminal 58

NIA - - - - - - - - - - - - - - - - - - - - -

O-7 VAC Y CT in Starter

1 Spare ________ __--_______-_-_----- ________------------

1 Neutral 1, “““““y I “..Vl I YII

Y 1 CWR & CHWR Coil

j TS4-9

115 NeutralI 115 N e u t r a l

115 Neutral~~ sN I Lube Box (OP & Htrs.) 1 115 Neutral

Y 1 Starter MCR Coils 115 Neutral

:,~ 1 115 Y’ 1 Output Relay ri9 Cooling Tower Fan RelayI

N Output Relay #13N 1 Oil Pump Contactor

] Lube Box (OL SW)

] Lube Box (OL Htr.)

N 3 Amp Circuit BreakerY Control Power Source

115 Volt Power Circuits

OP-Htrs. & Circuit Breaker

NOTES:Red Leads are 115 volt power

Yellow Leads are 24 volt powerWhite Leads are neutral ground

l Asterisk after Y in the Field Wiring column indicates that the device is an option. If the option is elected, Field Wiring is required

Field Wiring Required: Y = Yes; N = No

** Terminals 70 to 71 include a 250 ohm resistor wired to produce a one to five volt control signal.

Page 14 I IM 403

Fig1 Ire 14. Open Panel.

ALL FIELD COTO BE MADETHIS AREA OFTROL BOX TOMINAL STRIP.

Table 7. Outrmt Relav Switches

._._.._idnt

- - _ - _.=. 1 1 L-I

1 SB Solenoid & Light 4 - 3 24HGBP Solenoid 6 - 5 115

1 Sump Oil Heater1 Liquid Injection Solenoid

5 12-11--____6 14-13 115 I

Cycles #l Tower Fan24

115

115

72 6 - 2 5 115

* Relay Switch No. 3 wll have 115 volts or zero volts on both terminals depending upor; whet! er or not the circuit ?hrough relay No. 14 IS completed to controlpanel terminal No. 5A.

** USE CAUTION. Ground side terminals may carry 115 volt (or 24 volts) to ground even wher the relay is de-energized.

See “Recommended Testtng Procedure” for Solld-state Relay Switches.

IM 403 I Page 15

Figure 15. Daughter Board

NOTE: The daughter board colle& and condltlons dIgItal signals and delivers lh,: neww L Jtage levels to :he adjoinIng mplug-in ribbon cable

vzroprocessor thr

FUSE

TERMINASTRIP#TSl

ua

rL

LEDs located on the daughter board are identified as Ll, L2,L3, etc. These lights will glow when the contact in the ap-propriate protective circuit is closed. Contacts are +24 voltAC and must be closed, lighting the LED for the starting se-quence to be completed. LED numbered circuits are iden-tified in Table 8.

Table 8. LED Description

1 -- SURGEGUARD2 - MOTOR TEMPERATURE

‘1 O!L DIFFERENTIAL SWITCH

? - HIGH DISCt’ARGE PRESSURE5 -~ EVAPORATOR LOW PRESSURE6 --- PANEL SIARTSTOPi - STARTER cAUL.T

Y - CONDENSER FLOW & PUMP

9 -- EVAPORATOR FLOW & PUMP10 ~ STARTER TRANSITION

11 -- REMOTE START’STOP12 -- VANE CLOSE SWITCH

Table 9. Daughter Board Terminal Connections.

TS2-5 & 6 & 7 8 8TRANS.2 & TS2-4

TS2-7 & 6 Ei 5 8 4

Daughter Board

Daughter Board

NOTES:1. No field wiring required.

2. See Sensor and Control Connectlorl Taole for connections to terminal boards TSi, TS:!, and T! 13. ’ Pulsed volts to power status LED’s Zero volts LED “or”. 5 volts LED “off”4 ** Under control of the “Watchdog” cwcult

5. 12 volt AC and unregulated 17 VDC voltages are approwmate Actual values may be s/lghtlv m ‘? tir less6 See the Control Devices Table for wiring to daiighter board terminal strtps TSl TS3 arc 1%

Page 16 I IM 403

NOTE: No field connecttons required to this terminal block.

Figure 16. Typical Starter Connection Diagram [Control Only).

CPI

CP2EI C O N T R O L T R A N S F O R M E R (CPT)

C U R R E N T T R A N S F O R M E R A N DA D J U S T A B L E R E S I S T O R T O P R O V I D E5V;~;SSIGNAL A T R A T E D L O A D

0. TYPICAL TERMINAL NUMBERS

*IM = FIRST CONTACTOR TO HOLD IN.2M = SECOND CONTACTOR TO HOLD IN. IF NOTAVAILABLE SUBSTITUTE ;M.

** COmACTS SHOWN IN THE CLOSED POSITIONWITH THE IQ 1000 ENERGIZED

PE050/126 S T A R T E R C O N N E C T I O N D I A G R A M

IM 403 I Page 17

STARTING THE UNIT

INITIAL START-UP CHECKSThe following checks of the control system are recommend-ed before power is applied to the compressor.

1. Check that flow switches, interlocks, or jumpers (if required)are properly connected to MicroTech terminals 6 to 22, 10to 61, 10 to 63, 11 to 12, and 58 to 66.

Closure of these contacts during or prior to the start-upsequence is required to complete steps in the logic controlpath. S E E CAUTION STRIP TESTING

D on page 6.Proof’of closure of these contacts and others required

to be closed is given by the glow of appropriate LEDs onthe daughter board. (See Table 8).

2. If a remote start-stop control (SW2) will be used, the con-trol option must be activated in the logic panel (see Table17) and wiring must be connected across terminals 9 to 64.

Conversely, if the logic control panel has been set to call forthe remote start-stop option, then a connection must be madeacross terminals 9 to 64. If remote start-stop is not intended,then the programmable software must be left on “Local”. Usethe service or operator password, if required.

Check that hexadecimal switches (see Figure 17) on themother board and on the display EnGinn are properly set.Correct settings are shown in Table 11.

Check that the LED on the power cartridge and the LEDon the display EnGinn are blinking.If one is blinking and one is out, or if one or both are litcontinuously, or if both are out when they should be blink-ing, the condition indicates a fault which must be in-vestigated. See the Trouble Analysis section.

Energize the control panel without the compressor oper-ating, and check or set all desired options and requiredsetpoints.

HEXADECIMAL SWITCHES (Address switches)MicroTech control panels do not include any DIP switches toset. They do include hexadecimal switches (sometimes call-ed simply hex switches). These switches identify the com-

munications address by which one microprocessor providesand/or retrieves information to or from another.

There are two hex switches on the Control EnGinn and twoon the door-mounted Display EnGinn. When a Lead-Lag/LoadBalance panel is supplied, either with a dual compessor chilleror with two single compressor chillers, there are two morehex switches mounted on the Mother Board in this panel.

These switches are approximately 1/2" square, with an ar-row shaped screwdriver slot in the center face. Around theperimeter of the adjusting screw, the face of the square blockcontains the numbers 0 thru 9 and the letters A through F.

Next to or above each switch, on the mounting panel, let-tering will identify the switch as “Hi” or “Lo”. Do not assumethe ‘high’ or ‘low’ from their physical position.

Switches should be factory set. If there are two units beingconnected through a lead/lag MicroTech panel, the switch set-tings may not be correct. In any case verify that the arrowin each hex switch points to the number listed in the table.

IMPORTANT! If it is necessary to change the hex switchsettings, in order to input those new settings into the micro-processor memory, the panel must be powered down, thenre-energized. This can most readily be accomplished by trip-ping, than resetting the 3 amp control panel circuit breaker.

Fiaure 17. Hexadecimal Switches

* Arbitrarily select one of the units to be “Number 2”.

IMPORTANT! If it is necessary to change the hex switch settings, in order to input those new settings into the microprocessor memory, the panel must be powered

down, then re-energized. This can most readily be accomplished by tripping than resetting the 3 amp control panel circuit breaker.

Page 18 I IM 403

MECHANICAL PROTECTIVE SWITCH SETTINGSSee Table 12 for the recommended settings for the MechanicalHigh Pressure (MHP), Mechanical Low Pressure (MLP), andOil Differential Pressure (OD) protective controls.

Table 12. Setpoint Settings.

DRY RUNNING THE CONTROL PANELOn initial start-up of a new system, it’s desirable to dry runthe starter and control panel to check operation of bothoperating and protective controls.

This is usually accomplished with the compressor motorterminal leads disconnected at the starter, or at the motor (andtaped).

The absence of a motor amperage during the starting se-quence on MicroTech panels bearing the software version .07and later will result in a controlled shutdown and safety trip.This condition can be avoided by disconnecting either oneof the two D.C. voltage leads at the signal converter, or at ter-minal number 9 or 10 on the TS-4 terminal strip as the starteris energized. This action impresses a false amperage readingon the display Microprocessor which can be read on the 20character display if the motor amps keypad is pressed.

If, after energizing the panel, a flow switch, overload or othersafety is opened to prove the integrity of the control, the open-ed DC circuit must be reclosed if only momentarily to decaythe impressed amperage before a repetition of the startingoperation can be attemped.

Reconnect the disconnected lead before leaving the site.

gure 19. Solid-state Relay Position

~--_-_.--_---__---_--1

I

OUTPUTS j

IIIIIIIIIIIIIIIIII

MOTOR CONTROL I

R E L A Y L4TCHOUTIIIIIIIIIIIIIIIIII

_ _D_“_G Jo._7_0 es’oC_o_’ _RCVIo_A_ ;

IM 403 I Page 19

STARTING THE CENTRIFUGAL COMPRESSORPrior to starting the compressor, all procedural steps normallyassociated with starting a newly installed machine must befollowed. For detailed recommendations, see McQuay SM001and IM 392 covering general start-up and the IQ-1000 solid-state overload.

The proper direction of compressor motor rotation is vital,and may be determined:1. By means of a phase sequence test device.

2. By “bumping” the motor momentarily while visually obser-ving the direction of the motor rotation.

With a MicroTech control panel, a machine may be“bumped” only after all other start-up steps are completed.by starting the machine with a 115 volt control lead andpushbutton switch connected between terminals 25 at thestarter and 25 at the MicroTech control panel. The normal in-terconnecting lead must be disconnected at either end andthe end taped temporarily.

The pushbutton switch should be a thumb-held button.pressed and held to complete the circuit, suitable for 115 volts.50 VA. It should be connected to 115 volt wiring long enoughto reach comfortably between the control panel connectionand a point at the compressor motor end cover where the start-up technician can interrupt motor power instantly as the motorbegins to turn.

The sequence of timed functions such as “evaporator pumpon”, " waiting for load”, and “oil pump” pre-lube provide ade-quate time for the technician to get into place at the motor

Figure 20. Keypad.

end cover sigh: glass. The direction of the motor rotation cannow be determined within a few electrical cycles after the MCRcoils close energizing the compressor. The technician shouldthen immediately release the “bump” switch, opening the cir-cuit to the MCR relays and stopping the compressor.

Following completion of this last verification step (directionof motor rotation), shut off the control circuit power at itssource. disconnect the “bump” switch wiring and reconnectconventional control wiring.

Prior to re-connecting control power and energizing thecompressor power circuit, it is often possible and desirableto set the current transformer circuits’ variable reisistor follow-ing a quick calculation. Using the compressor RLA, and thecurrent transformer’s primary to secondary ratio, calculate theresistance in ohms required to produce 5 volts AC.

Transf. Sec. Ratio1 RLA x .~. _ i._.__ x j1.0, .50 or 581’=CT output ampsTransf. Pr imary Ratio

* If the current transformer IS in the main line use 10; use 058 if the CT IS

in a phase leg (Star-Delta starters): use .50 i f dual conductors are used onacross the l ine or, autotransformer starters and only one lead out of s i x i s pass-ed through the CT

2 Calculate the required ohms from the CT output amps asfollows

5 Volts ~ = Resistance m ohmsCT outpu t amps

Since the MicroTech panel will accept between 5.0 and 7.0 voltsAC, recalculate step 2) using 7 volts

Page 20 / IM 403

Figure 21. IQ-1000. Figure 22 IQ-Data Pius.

Figure 23. Typical Variable Resistor & Typical Current Transformers. - -

c

--

NOTE: If the unit has 2 resistors in parallel providing the ACvoltage signal, see Catalog SM001 for calculation of the prin-cipal resistance.

Using an ohmmeter, set the variable resistor for a resistancebetween the two values calculated.

Reconnect any loose leads and connect both iines and con-trol power.1.

2.

3.

4.

5.

‘Close all interlocks and switches to energize the com-pressor motor.

Connect an amprobe around the line or phase leads tothe motor at the motor starter

Note the compressor motor rated load amps (or requiredphase amps to equal motor rated load amps)

Press the “manual vane control” switch on the controlpanel keypad. If the display requests a password input.comply with the operator or service password. If thedisplay begins blinking “[ + ] load, [ - ] unload” the unitwill be in a hold position.

Press the display section “motor amps” keypad once todisplay “motor percent RLA = X X % The message wilibe blinking indicating a continuance of the manual vanecontrol mode.DO NOT watch the MicroTech display for this step. Bringthe amps drawn by the compressor motor up to Rated

7.

8.

9.

10

Load Amps, (nameplate RLA).

Stop loading the compressor at the design RLA. NOTE;when neither the “+/Yes” nor “-/No” keypad is beingpressed the compressor vanes will be in a hold positionif the display is blinking.

If for some reason, a further “lock” on the RLA hold posi-tion s desired the needle valves in the SA-SB solenoidports may be closed.

If the 5 to 7 volt AC signals’ resistance was not calculatedas stated previously, with the compressor drawing ratedload amps, carefully and cautiously adjust the starter’svariable resistor to obtain a 5 to 7 volt AC signal betweenterminals 1 and 2 (or 2A) on the MicroTech’s field con-nect on terminal strip. (see SM001.)

With the line ammeter showing Rated Load Amps, and5 to 7 volts AC present at terminals 1 and 2 (or 2A) asnotes above, use a small screwdriver at the trim pot ofthe si gnal converter board in the MicroTech panel to dial17’ a display reading of 100% amps. When this readingis obtained, the signal converter will be delivering +4volts DC to the Microprocessor daughter board TS4 ter-minal No 9.

If the display reads 100% amps at actual compressorRLA as read on the ,lne connected ammeter, no furtheradjustment IS necerrratrr .

IM 403 / Page 21

OPERATION

OPERATING SEQUENCE pletion of this starting step.The following describes the unit’s normal operating sequenceprovided the time delay requirements are met and no safetycontrol has tripped or holiday schedule set to keep the unit off.Place the control panel “Stop-Auto” switch in the “Auto”position.

In this position the switch is engaged and the unit may bestarted provided:1. The chilled water sensor is calling for cooling.

2. No time delay is restraining operation.

3. A remote start-stop switch (See SW2 in the control wiring),is not open preventing unit operation.

4. No safety switch has been tripped and not reset.

Press the “Start Unit” key switch. The following messagesappear in the display screen, in sequence, indicating actionwhich has taken place.

7. Within 5 seconds of energizing the condenser water pump,if the compressors’ vane closed switch shows the vanesto be in a closed (compressor unloaded) position, the logicoutput circuit (14) is completed through closed mechanicalcontacts to control panel terminal 5A, back through thesolid-state latch-in circuit, and through to the main starteroperating coils, (MCR1, and MCR2).

The latch-in circuit is a normally open contact solid-staterelay. Upon the application of a logic signal, the relaycloses its contacts instantly. They remain closed for 3seconds, then open. The operating contacts are in parallelwith normally open MCR coil contacts. These close andserve to prove the operation of the compressor motorstarter coils. Closure of interlocks, and the transition relayalso serve to confirm normal and complete starteroperation.

FUNCTIONWill start in XX minutes*

COUNTDOWN TIME

Evaporator pump on. 2 0 (seconds)W a i t i n g f o r l o a d . . ( V a r i a b l e ) ( s e c o n d s )O i l p u m p i s o n ( V a r i a b l e ) . 3 0 or 60 (seconds)C o n d e n s e r p u m p i s o n ( A d j u s t a b l e ) . 05 (seconds)M C R i s o n .:‘I X X ( s e c o n d s )Unit is running okay* Programmed safety time delayed start is based on a factory set 40 minutestart-to-start but not less than 3 minutes between stop-to-start.

8. Throughout this entire process, conventional protectivecontrols remain active to interrupt the starting sequencein the event of a fault.

The statement displayed “Waiting for load” in the above se-quence, and the countdown period in seconds assigned toit, assumes that the water temperature sensed by the chilledwater temperature sensor may not represent the entire chill-ed water system temperature if the chilled water pump hasbeen shut off. This delay interval provides time for the chill-ed water pump to circulate system water and impart a validsystem water temperature to the chilled water sensor.

In the starting sequence:1. A call for cooling will energize the control through the logic

output circuit to the evaporator water pump relay coil.If the circuit to this solid-state relay is completed the LED

at the solid-state relay supplying that control power willglow.

9. An incomplete sequence is recorded as a fault and trip.If the fault occurs because of the failure of the logic out-put circuit to complete a sequence, the solid-state relay’sLED may be lit, but the LED on the daughter board for thatcircuit will not be lit. NOTE: a blown fuse in the solid-staterelay circuit (see Figure 29), or an open in the operatingcircuit beyond the solid-state relay will not prevent the solid-state relay’s LED from being lighted. See section on Trou-ble Analysis.

2. If the evaporator water pump relay’s operation results inoperation of the chilled water pump, then closure of proofof flow contacts and interlocks will permit the next step.Proof of flow will also light LED number 9 on the daughterboard.

TEMPERATURE CONTROL OPERATIONTemperature sensors are negative co-efficient thermistorsselected for extended accuracy and close control. During com-pressor operation from 10% to 100% capacity chilled wateroperating temperature will be held to within +05”F.

The operator shall input the design leaving chilled watertemperature by first pressing the water temperature keypadunder the “Setpoints” section of the control panel.

The setpoint value listed in the program will then bedisplayed in the window above the keypad.

If the value displayed is the desired temperature, no fur-ther action is required. The “Cancel, Clear Display” keypadshould be pressed to clear the screen.

If the value displayed is not the desired setpointtemperature, the value may be changed by:

3. An oil temperature sensor (#10) must indicate an oiltemperature at least 40°F above the saturated refrigerantevaporator temperature (#2 sensor).

4. If steps 2 and 3 are satisfied, the oil pump contactor isenergized through the logic output circuit. The oil pumpmotor is started.

1.

2.

3.

4.

5.

Press the “+/Yes” or “-/No” keypad. The display will read“Enter Password” if a password has not already beenentered. NOTE: All setpoint and service changes requireuse of a password.

Simultaneously with the starting of the oil pump motor,the 115 volt circuit supplying power to the oil pump heatersis opened de-energizing them.

Enter the required password. The operator password maybe’ entered by pressing the “?/HELP” keypad four (4) timesin succession.

The display will then read, “Operator Password Okay”.

5. With the oil pump operating, a minimum oil pressure of60 PSIG above evaporator pressure is required to com-plete the sequence for the next step.

6. Following proof of adequate oil pressure and the passageof a 60 second prelube time, the condenser water pumprelay is energized, through the logic output circuit. Againproof of the logic instruction to this circuit is evidenced bythe glow of this solid-state relay’s LED. If the CWR relayis energized and this action results in closure of the flowswitch and interlock between terminals 10 and 61, LEDnumber 8 on the daughter board will glow, confirming com-

Re-press the water temperature setpoints keypad to displaythe leaving chilled water temperature. To raise the valuedisplayed, press the “+/Yes” keypad. To lower the valuedisplayed, press the “-/No” keypad.

When the revised, desired, setpoint is displayed, it mustbe entered into the program by pressing the “=/Enter”keypad.

Other Operator controlled setpoints are changed in the samemanner. The cycling “on-off” thermostat function is programm-ed into the MicroTech software. An operating unit will shut offwhen the leaving chilled water temperature is pulled down,(at 10% compressor capacity) to 2°F below the leaving chill-

Page 22 / IM 403

ed water setpoint. The thermostat will reclose, initiating a com-pressor stat-l when the chilled water temperature rises to 2” Fabove the setpoint.

These values are adjustable as described in the keypadsection of this manual.

SOFTWARE VERSION NUMBER CODE INFORMATIONThe Logic Cartridge on the mother board, the Display EnGinnon the back of the keypad door, and the logic cartridgemounted inside the lead-lag/load balance panel (where us-ed) all contain the software information required to control andprotect the chiller.

For varied reasons, there are different software versions.On any single compressor chiller, the software version on

the Logic Cartridge and the Display EnGinn must be the

same.On any dual compressor chiller, the software on both

MicroTech panels Logic Cartridges and Display Enginns, andthe Lead-Lag/Load Balance Logic Cartridge must all be thesame.

On any two chillers on the same installation using aseparate Lead-Lag/Load Balance control, the software pro-grams on all programmable components must all be the sameversion.

In addition, whenever inquiries are being made, or program-mable components replaced, the Version number must befurnished to McQuay.

Version number codes for the three (3) basic components,and their location on the components are shown below.

DISPLAY ENGINN CODE(Software Version Number Code is found on the label attached to the upper right-hand side of the Display EnGinn.)

PDROSF

R = United States TerminologyM = Metric Terminology

LOGIC CARTRIDGE CODE (CONTROL ENGINN)(Software Version Number is found on the label attached to the upper spine of the Logic Cartridge.)

PD208F

P = Centrifugal Chiller

D = Control EnGinn (Logic Cartridge)

2 = Refrigerant R-12

LOGIC CARTRIDGE CODE (LEAD-LAG/LOAD

DUA 08 D

-T-TT

5 = Refrigerant R-500

BALANCE)

May Also Be DUALSIndicates Dual Unit Controller

Revision (A, B, C, etc.)

Version Number (07, 08, etc.)

IM 403 I Page 23

OIL TEMPERATURE.To maintain a separation of refrigerant and oil in the refrigerantatmosphere, the oil must be heated to a temperature approx-imately 40°F to 50°F above saturated refrigerant (Evap.)temperature.

During normal compressor operation, saturated refrigerantevaporating temperature is less than leaving chilled watertemperature, and sufficient heat is added to the oil by the fric-tion of shaft journals rotating in the bearings. With the com-pressor “off”, the saturated refrigerant temperature rises, ap-proaching ambient, and the oil must be heated to maintainthe required temperature difference.

Heat is applied to the oil when the compressor is “off” bythe operation of one or two electric resistance heaters locatedin the oil sump. The heaters are wired, electrically, throughthe oil pump contactor. When the contactor is energized, andthe oil pump operating, the circuit to the oil sump heater(s)is open, and the heaters are “off”. When the compressor, andoil pump are “off”, the contactor is de-energized and theheater(s) energized.

To protect the compressor from operating with refrigerantladen oil being delivered to the bearings, the MicroTech soft-ware includes a protective control located under the ServiceSetpoints key. Press number 5 of that key will show, “Low OilDelta=XXX”. The setting may be Service adjusted between40°F and 60” F; and is factory set for 50°F.

If the oil temperature is not equal to, or above the Low OilDelta setpoint plus the saturated refrigerant (Evap.)temperature, the unit will not start, but will display the state-ment “Waiting Low Sump T”.

If the chiller is running and the oil temperature in the sumpfalls below a temperature equal to the saturated refrigerant(Evap.) temperature plus the Low Oil Delta setpoint, the chillerwill cycle “off”, and one press of the “Fault History” key will

Page 24 / IM 403

produce the display “Now=Low Sump Temp”.The two sensors that produce the actual calculated

temperature difference are the oil sump sensor (Number 10)and the Evap. Saturated Refr. Temp. sensor (Number 02).

The Low Oil Delta setpoint also serves a second function.It’s temperature setpoint plus lOoF, plus the saturatedrefrigerant (Evap.) temperature is displayed as the “Calc OilSPT” temperature. This is the oil temperature that the com-puter software will attempt to maintain when the chiller is “off”.

As described above, electric heat is applied to the oil whenthe compressor is “off”. That heat increases the oiltemperature to the calculated oil setpoint temperature andmore.

When the temperature increases to 4°F higher than thecalculated setpoint temperature, the solid-state output relaynumber 5 de-energizes, opening the circuit to one sumpheater. As the oil cools down to the calculated setpointtemperature, the relay re-energizes and additional heat isagain added to the oil. In this manner, the oil temperature ismaintained within a 4” F to 5” F temperature of the calculatedsetpoint during compressor “off” cycles.

An additional oil temperature protective control preventsoverheated oil from being delivered to compressor bearings.This protection is a “High Oil Feed” temperature, and its valueis determined by measurement through the “Oil Feed Temp”sensor, (number 09).

If the oil temperature at the oil feed sensor exceeds the set-point temperature when the chiller is running, or “off”, a faultcondition will occur.

Based upon all of the above, it will be desirable to set thecontrol setpoints while considering both compressor operatingand “off” conditions to prevent overlapping temperatures andnuisance tripping.

_

THE KEYPADThe keypad consists of 24 touch sensitive membrane key swit-ches that provide a total of over 160 separate statements regar-ding the operation, setpoints, and service history of the con-trolled chiller.

To provide the abundance of information from so fewkeypads, many of the keys must be pressed more than once.When pressed, Display section keys, for example, display asingle statement. The next press of the same key displaysthe next statement in that scroll. Subsequent keystrokes ofthat same key will complete the presentation of the functionsassigned to that key, and will begin again if the key is re-pressed following completion of the series.As an example, if the “Water Temps” keypad is pressed;

once: the statement appears “LEAVING EVAP =Xx.X” F”twice: the statement appears “ENTERING EVAP = Xx.X” F”three: the statement appears “ENTERING COND = XX.X”F”four: the statement appears “LEAVING COND = XX.X”F”five: repeats No. 1 “ENTERING EVAP=XX.X”F”etc.

For simplicity a table is provided listing the number ofkeystrokes required for each key to display it’s allocated in-formation, and the information statement. The keys do notscroll backward. If review of a preceding statement is desired,the Cancel, Clear Display keypad, or any other, may be press-ed, then the original keypad re-pressed. The lead, or first-press statement will appear. It’s also possible to scroll onthrough with sequential keystrokes, to complete the cycle andbegin again.

Under the Display section, two keypads operate just slightlydifferent from the rest. Pressing “Unit Status” once will pro-duce any one of eighteen (18) different statements. Thosestatements depend on the present mode of the unit and aretabulated below:

First press - “Unit Status” - Statements.

OFF Mode (See Operational Status)Off: Waiting for system loadOff: Due to Fault

Start-up SequenceWill start in XX minutesWaiting: Low Sump Temp.Evap. Pump is On XX (seconds)Waiting for Load XX (seconds)Oil Pump is On XX (seconds)Cond. Pump is On XX (seconds)MCR is On XX (seconds)Unit is running ok

Shutdown SequenceStop Unloading XX sec.MCR OFF Post Lube

Operational StatusWaiting, High AmpsOFF, Load RecycleOFF, Time ScheduleOFF, Remote SignalOFF, Manual SwitchOFF, Ready to Start

Pressing the “Unit Status” keypad a second, third, fourth,etc., through eight strokes will reveal whether or not any orall of seven (7) options have been activated. See the Tableof Keystrokes Displays for information of the options available.See the description under the Service, “Set Up Options”keypad for information on how to activate options.

The second different keypad under the Display section isthe “Data Scroll” key. Following a single press of this key,a complete list of all of the functional values available in theDisplay section and other data will be displayed, each for aninterval of four (4) seconds. This scroll will begin with “Unitis Running OK”, and end following 52 intermediate statementswith a repetition of the same “Unit is Running OK”. The in-termediate statements are tabulated in a form to permit ser-vice personnel to record the data. These statements includetemperatures, pressures, amps, options, setpoints, operatinghours, and faults (if any).

The Setpoints Section does not contain protective settings,but does contain the leaving Chilled Water SetpointTemperature, Reset Options, % of Amp Limits, Soft Load,Time and Holiday Schedules, and the means to change thosechangeable values impressed in the Microprocessor memory.See the keypad Table for a listing of the information displayedwith each Setpoints key press.

The following paragraphs describe specific functions andtheir operation.

To change a Setpoint (or input an option)1. Press the setpoint or setup option keypad.

2. With the setpoint or option statement displayed, pressthe “+/Yes” or “ -/No” key.

3. The display will than read “Enter Password”, if it has notpreviously been entered and remains active.

4. Enter the operator or service password, as required. SeeTable 2.

The Operator Password is 4 consecutive keystrokes of“?/Help”.

5.

6.

7.

8.

9.

10.

The display will read “Operator (or Service) PasswordOK’:

Repress the keypad representing the function to bechanged.

With the statement or value displayed, press “Yes” or“No”; " + ,, or " - " to activate or de-activate an option;increase or decrease a numerical value. For largechanges in numerical values, hold down the “+/Yes” or“-/No” key until the desired value is reached.

The statement or numerical value will be blinking in-dicating that a change in setpoint has been requested.

To input the new value into the Microprocessor memory,press “=/Enter”. The display will stop blinking.

If after reconsideration, the new statement of value is notwanted, do not press “ =/Enter”, but instead press“Cancel, Clear display”. The original value will remainin the microprocessor memory.

PASSWORD INFORMATIONOnce a password has been entered, it remains active for aninterval of ten minutes from the time of its use. For exampleif a password is entered and used eleven minutes previous-ly, it will have disappeared from the system. If, on the otherhand, it was used nine (9) minutes ago, another setpoint maybe changed without again re-entering the password. In addi-tion, following this latest setpoint change, the password in-terval is extended for another ten minutes.

To withdraw the “password OK” status press “Cancel, cleardisplay”. Doing so will cause the password approval to ex-pire in one minute.

IM 403 / Page 25

“WATER TEMPS” KEYPAD (Setpoints)Actual water temperature is displayed by pressing the “WaterTemps” keypad under the Display section.

To display the leaving chilled water setpoint temperature,press the “Water Temps” keypad under the Setpoints sec-tion just once. LVG EVAP SPT= XX.XF will be displayed. Thisis the temperature setting to which the compressor vanes willrespond; opening and closing, loading and unloading to main-tain the operating temperature at the setpoint temperature.

This is the temperature also that is used as a base againstwhich the compressor will start and stop. See the descrip-tions for the “Start-up Temperature Difference” and “Shut-down Temperature Difference”. These latter statements aredisplayed by pressing the “Set-up Options” keypad.

Pressing the “Water Temps” (Setpoints) keypad a secondtime will display’the statement “Reset LVG SPT=ZZZ”.

The three Z’s indicate letter options which in this case wouldbe “N/A” for not active, CHW for chilled water, and ENT forreturn water temperature reset.

See the section marked Reset Control for a description ofreset opportunities with MicroTech.

Keep in mind that these statements and others under thisSetpoints section are statements only. To input these valuesor statements, press the “Set-up Options” keypad under theService section, and follow the instructions given in the follow-ing section, “Set-up Option”. A third press of the “WaterTemps” (Setpoints) key will display the statement “RMT ResetSIG=N/A” or ".... =Xx.X”. The three X’s indicate that thedisplayed value will be numbers that represent the milliamp(mA) value impressed.

If the option to reset based on “CHW” is elected, a 4 to20 mA signal is required. The signal is input at terminals 69,70 and 71 on the Field Connection terminal strip (single unitinstallation) or at the Lead/Lag Load Balance control box ontwo-unit installations.

If the option to reset based on “ENT” is elected, no remoteReset signal is required.

“Max Amp Limit” keypad also provides multiple statementswith each of 3 separate strokes of the keypad. The firstkeystroke and statement “Max Amp Lim = XX% indicates themaximum % of Rated Load Amps that the chiller will be per-mitted to draw. The setting cannot be increased above 1 0 0 %nor lowered below 30%. This control provides a manual limitof power consumption which may be used in mild weatherto save energy.

Automatic reset of amps is possible also by activating theAMP reset option (“Set-up Options” key) and inputting a 4to 20 mA signal. If this has been done the second press ofthe “Max Amp Lim” keypad will display this information. Athird press will display the currently impressed remote mAsignal.

SOFT LOAD KEYPADEach centrifugal compressor must have its mechancial vaneclosed switch in the “closed” (10% capacity) position to per-mit completion of a unit start. Following start-up, it may bedesirable to limit the loading of the compressor for energyconservation.

“Soft Load” provides that additional control. When press-ed consecutively the “Soft Load” keypad produces the follow-ing three statements.

First, “Soft Load Limit=N/A” (or XX%). If activated, this limitis the maximum percent of RLA at which the compressor willbe allowed to operate based upon the setting of the MAX AMPLIMIT key. This value may be set anywhere between 30% and100%.

Second, “Beginning Amp Limit = XX%“. This value is alsoa percentage of rated load amps (RLA). It represents the com-pressor ampere percentage at which the soft loading will beginits’ time controlled increase up to the maximum percentage

Page 26 I IM 403

of step one. This value can also range between 30% and100%; but must be a lower setting than the setting displayedin the first keypress, (above).

Third, “Ramp up time=XX min.“. This value is expressedin minutes and defines the time period over which the com-pressor can load from the “Beginning Amp Limit (percent)”to the upper “Maximum Amp Limit (percent)” or “Soft LoadLimit (percent)“.

The time is adjustable from zero to 120 minutes.

If the Soft Load feature will be activated, press the Soft LoadKeypad three (3) times to display the statement “Ramp UpTime=XX min.“. If the value displayed is “0” minutes, the firstkeypress of the Soft Load Key will have displayed the reading“Soft Load Limit = N/A”.

Insert the desired ramp up time into the program memoryby following the procedure described under the section “ToChange a Setpoint”. Simply by inputting a time frame greaterthan zero in the “Ramp Up Time” function, the Soft Load Limitbecomes activated. Returning to the first keypress of thiskeypad will then display the percentage that will representthe maximum load that the unit capacity will operate at follow-ing completion of the time period.

If this percentage should be changed, return to the firstpress of the Max Amp Limit keypad, and increase ordecrease the allowable percent.

Return to the Soft Load Limit keypad. The first press ofthis keypad will display the % RLA input under the Max AmpLimit key. The second press of the Soft Load Limit keypadwill, as described above, show the “Beginning AmpLimit=XX%“. This later percentage value can be increasedor decreased within the 30 to 100% range by pressing the“+/yes” o r " -/No” keypads following insertion of thepassword.

Note that the % amps consumed by a centrifugal com-pressor are not directly proportional to the % capacity of thecompressor. The 30% amps figure in less than the amps nor-mally drawn by a compressor operating at 10% of capacity.The 30% amps ‘number’ is, therefore, representative of theminimum compressor capacity. Actual amps drawn at 10%capacity will vary based on compressor motor power factorand efficiency characteristics, and by chilled water and con-denser water operating temperatures.

Figure 25. Soft Load Performance.

100

t 90zzia 60,

5g 70,

2Z 60,

s‘r 502= 4 0

30

k 90i 60

!h

/

4

s70

SELECTABLETOP fl

0(% AMPS & TIME)

z 602 AND

BOTTOM(% AMPS ONLY)

40

30-l0 60 120 MAX.

RAMP UP TIME (MINUTES) ADJUSTABLE

CLOCK SCHEDULE KEYPADThis keypad requires a total of 49 keystrokes to sequence en-tirely through the loop. See the keystrokes sequence tablefor individual keystrokes information. In summary, the ClockSchedule keypad provides:l Current date and timel Weekly and daily on-off time schedulesl 14 holiday “off" schedulesl An over-ride function to counter a programmed “off” periodl And a Master “off” function to over-ride the daily, weekly,and holiday schedules entirely.

Most of these function are self-explanatory. All can bevisualized in their place on the printed Clock Schedule table.A brief explanation of some of these steps follow.

When shipped, each unit has the date and time set but theclock control program de-activated.

De-activation of the daily and weekly clock control scheduleis accomplished by setting the S1 display (the 10th press ofthe “Clock Schedule” keypad) equal to “Off”.

If the operator wishes to activate the automatic controlschedule, including holidays, S1 must be changed to Sun-day, Monday, etc., or whichever day is to be considered thefirst day of controlled operation. Subsequent keypresses willset the time of start-up and shutdown.

Reference to the Clock Schedule Table will show that a se-cond weekly control schedule may also be incorporated.NOTE: On dual compressor units, it may be desirable to setthe clock schedules for each of the control panels at the samevalues. At the very least, clock schedules on dual compressorunits must be turned “On”. This is accomplished by setting“S1 First Day=Sun.

OVER-RIDE CONTROLIn the event the clock schedule time and holidays have beenpre-set, and it becomes desirable to turn the chiller “on” ona scheduled “off” day, it is not necessary to re-enter the pro-gram and alter the entire schedule.

Simply press the Clock Schedule keypad twice. “Over-ride(Hours)=X.X” will appear on the display. With the passwordentered, press the “+/Yes” key. Numerical values for thedesired number of operating hours will be shown in thedisplay. Press enter to insert the time into the control memory,and if water temperature, control power, and interlocks per-mit, the unit will start.

Assuming that the chiller will not satisfy the watertemperature, or experience a fault condition, the unit will se-quence through a controlled shutdown following passage ofthe alloted hours.

" +/Yes”, " -/No”, " =/Enter”These keys are used to input desired options, raise or lowersetpoints and protective settings, and enter the chosen valueor statement into the Microprocessor memory.

See the earlier paragraph headed “To Change A Setpoint”.

MANUAL VANE CONTROLFor service purposes, it’s sometimes necessary to put anoperating compressor into a manually controlled capacitymode.

A password must be entered, and the “Manual Vane Con-trol” key pressed. This display will immediately begin blink-ing “[ +] Load, [ - ] Unload”. This flashing statement indicatesthat the unit is in manual control and is in a holding position.

In this position other keys such as “Water Temp”, “UnitStatus”, “Motor Amps”, etc. may be pressed. They will displaythe operating value, but in each case, the entire statementwill be flashing, indicating that the unit is under manualcapacity control. If, for example “Motor Amps=XX” isflashing, pressing the “+/Yes” keypad will load the machineand the increase will be reflected by an increase in the ampvalue displayed, provided higher amperage is permissable.

Similarily, if unloading is desired, pressing the “-/No” keypadwill display a reduction in amps confirming that the com-pressor has unloaded.

Remember, if the entire displayed message is flashing, theunit is in Manual control. To return the control to automatic,press the “Cancel, clear display” keypad.

If the chiller control is accidentally left under manual con-trol, the display and manual operation will automaticallycancel itself after 10 minutes of no keystrokes.

“FAULT HISTORY”, “CLEAR FAULT”If a unit trips due to a fault, the first press of the “Fault History”keypad will display the cause. Pressing the keypad eight moretimes will display the previous eight faults, thereby providinga pattern for service analysis.

Following correction of the actual (current) fault, the “ClearFault” keypad must be pressed to permit restarting the unit.Possible safety faults are listed below. (Words in parenthesisare not displayed).

Some versions of software may also include “High MotorCurrent” or “Low Motor Current”.

In all cases the general reason for the outage will beself-explanatory.

NO TRANSITION (Starter)

LOW SUMP TEMP (Oil)HIGH FEED TEMP (Oil)

LOW EVAP PRESS (Refrig)HIGH DISCHARGE PRESS (Refrig)

HIGH DISCHARGE TEMP

SURGE (Compressor)HIGH SUCTION TEMP (Refrig)

HIGH MOTOR TEMP (Guardistor)STARTER FAULT (Overload)LOW CHARGE SW (MLP)NO EVAP FLOW (Water)

NO COND FLOW (Water)

LOW OIL PRESS (OP)HIGH PRESS SW (MHP)

LVG EVAP WTR SENENT EVAP WTR SEN

EVAPORATOR SEN (Refrig)

SUCTION SENSOR (Refrig)

LIQUID LINE SEN (Refrig)

ENT CND WTR SENLVG CND WTR SENDISCHARGE SEN (Refrig)CONDENSER SEN (Refrig)

OIL FEED SENSOROIL SUMP SENSOR

OIL PRESS SEN

VANES OPEN

IM 403 I Page 27

“SET-UP OPTIONS”This keypad will produce seventeen or eighteen separatedisplayed functions (depending on the software version) witheach separate press of the keypad. Each is listed in thekeypad table with the individual options or ranges shown.

The first of these are Reset Options. There are six (6) op-tions associated with this function. They are:

1. None 4. ENT2. AMP 5. AMP ENT3. CHW 6. AMP CHW

If one of these options is to be selected, the statement“Reset Options= “ZZZ” in this example represents any oneof the 6 options listed. To change the displayed statement,press “+/Yes”, or " -/No” keypad. With the desired optiondisplayed, press “=/Enter” to establish the option in theMicroprocesor memory. If reset options are chosen, their in-clusion in the program will be displayed by successivekeypresses of the Setpoints section keys,--"Water Temps”and/or “Max Amp Limit”,

For a detailed explanation of the available “Reset” feature,see the subsection “Reset Options”.

Tower Staging will control cooling tower fan operation; butonly if the control relays required are field installed, and wiredto initiate the operation of one or more tower fans.

Enable Lag, Disable Lag, and Delay Timer “Set-up Op-tions” are control values that are required only if the unit isone of two compressors (PF unit), or two units connected ina “Lead-Lag/Load Balance” configuration.

For a detailed explanation of these three functions, see thesection marked “Lead-Lag/Load Balance’:

TIME CONTROL FUNCTIONS (Not Clock Schedule)Statements such as “Waiting High Amps” or “Waiting -LowSump T” are time dependent, but they can not be modified

Table 13. Time Controlled Functions.

by an adjustment of the time interval.To assist the operator, the following provides a summary

of timed functions, whether or not they are adjustable, theirlocation, and time frame.

A brief description of each listed function follows:

Start-to-Start / Stop-to-Start-These two timers limit the fre-quency of motor starting to assure longer motor life. Cen-trifugal compressors unload to 10% and continue to operateuntil the water temperature is overcooled by a few degrees.The combination of compressor capacity reduction andtemperature control are intended to minimize the need for toofrequent starting. If more frequent starting seems to be re-quired to prevent wide temperature fluctuations, the applica-tion or equipment and system control should be examined.

Oil Pump is On / Post Lube (Oil Pump)-These two timefunctions provide bearing lubrication through time controll-ed operation of the oil pump both before and after compressoroperation. The time periods alloted are satisfactory for all sizesof McQuay Centrifugal compressors.

Condenser Pump Timer-This timer determines the lengthof time the condenser pump will operate before the main com-pressor motor control relays (MCR) are energized. Some ex-tended time may be required; but only if a delay is requiredto refill the system, average condenser water temperature, orprove closure of system flow controls. A long condenser pumptime interval, without the compressor operating is notdesirable. Five to ten seconds is adequate.

An exception to the short time interval exists where one con-denser pump serves two or more machines. In this case, thepump might be running for a very long period of time withthe second or third chiller inoperative.

-_

i

Start-Up OptionStart-Up Option

None (Software)

None (Software)

Start-Up OptionStart-Up Option

Start-Up OptionStart-Up OptionNone (Software)Clock Schedule

Soft Load

None (Software)

20 min. to 60 min.3 min. to 20 min.

30 sec.

30 sec.

5 sec. to 240 sec.

2 min. to 60 min.1 min. to 10 min.

15 sec. to 240 sec.30 sec.0 to 51 hours

0 to 120 min.

Seconds

Page 28 / IM 403

Ent Evap. Timer-This timer is an integral part of the “Enter-ing” chilled water temperature reset feature. As the buildingload changes, entering, or return, chilled water temperatureincreases or decreases. At fixed time intervals, the softwarecompares return water temperature and leaving chilled watertemperature. If the time interval is too short, over-adjustmentand hunting may result; if it’s too long, system inefficiencymay exist. The actual setting should be adjusted to suit thejob system characteristics.

Delay Timer-The “Delay Timer” applies only to dual unitor dual compressor installations. The second, or lag com-pressor, will not be started unless the lead compressor’soperating amps exceeds the Enable % RLA for the preset“Delay Timer” interval. Conversely, the lag compressor orchiller will not shut off unless the lead compressor’s operatingamps is less than the Disable % RLA for the preset “DelayTimer” interval.

In this manner, unnecessary cycling “on” and “off” of thelag machine is avoided.

Load Delay (Waiting for Load)-Where energy efficiency dic-tates that a chilled water pump be shut off when its chilleris inoperative, water temperature within the piping system mayvary widely depending upon the ambient temperature condi-tions. The “Load Delay” timer permits the chilled water pumpto circulate and mix chilled water in the piping system beforethe chiller is actually started. By so doing, the temperatureimparted to the chiller’s water sensors more closely resemblesthe total building water temperature. The Load Delay time in-terval should be set shorter or longer as the mass of waterin the building’s system is comparatively little or great.

MCR Is On (or Stop, Unloading)-The time interval associ-ated with the MCR operation is intended to establishreasonable delay for closure of the starter transition contacts.“Stop, Unloading” provides a time period to permit the oilpump to close the compressor vanes.

Override (HRS)-This feature permits overriding the establish-ed clock schedule to operate a unit on an “off” day, withoutchanging the entire schedule. The desired number ofoperating hours are entered into the program and the regularschedule will be overridden for that number of hours.

Soft Load (Ramp Up Time)-The soft load ramp up timeestablishes a period that may be as long as two hours to per-mit a controlled increase in chiller capacity. During that con-trolled time interval, it’s possible that the sizeable cooling loaddeveloped only by a weekend shutdown may be reduced toa manageable partial load at less than maximum electricaldemand.

Step and Wait-Within a range of plus or minus two tenths(0.2”F) of a degree Fahrenheit of the chilled water setpoint,the compressor capacity control system will “hold,” neitherloading or unloading the compressor. As the leaving chilledwater temperature drifts above or below the setpoint withina range of two tenths (0.2) to two (2.0) degrees F, the com-pressor will pulse control to the unload or load solenoids,respectively, to return the water temperature to setpoint.Should the chilled water temperature drift away from setpointbe more than two (2.0) degrees F, as it might be following anovernight shutdown, loading is continuous until this watertemperature returns to within 2.O”F of the CHW setpoint.

OPERATION OF THE LEAD-LAG/LOAD BALANCE PANEL

GENERAL (See IM 425-2 for the latest LLLB)The LLLB controller is provided with an internal 3 amp cir-cuit breaker switch, or a cover panel mounted “on"--"off”switch. When power is applied, and the switch closed, an LEDstatus light in the front cover panel will blink.

LED’s will blink also on the cover panel to confirm the opera-tional status of controller number l’s microprocessor, and thatof controller number 2. Another LED will indicate which com-pressor or unit is the “Lead”.

Lead-Lag - A three-position switch on the front cover panelis marked

* Controller (Number) 1 Leadl Auto Lead, (and)* Controller (Number) 2 Lead

If the switch is positioned to either Controller 1 or Controller2, that unit will be the lead unit, and the other, the lag.

If the switch is positioned for Auto Lead, the computer willread the operating hours of the two machines and select theone with the least operating hours to be the lead. A changefrom one lead unit to the other will only occur when both unitsare off, or both are operating. In this manner the units areprotected against a sudden switch in the lead unit selectionas the hours of the operating machine overtake the operatinghours of the other (off) machine.

Lag Start-Stop - The lead machine increases its capacityto satisfy an increasing cooling load. When this compressor’smaximum capacity is approached, at a pre-set value inputunder the “Set-up Options” key, the signal is communicatedto the lag machine to start and run. The operating signal is“Enable Lag” and it is set based on the percent of the Lead

units operating amps. The Enable Lag cannot be set for lessthan 8 0 % nor more than 100%. A normal recommended set-point is 95%. Further, the lag machine will not start immediate-ly when the % amps reaches the setpoint. A “Delay Timer”setpoint requires that the % amps consumed equal or exceedthe setpoint % amps for the period of time programmed.

In this manner, unnecessary cycling is avoided.A third setpoint, “Disable Lag = XX%,” also requires setting.This too is a % of the lead compressor’s operating amps. Thevalue may be set anywhere between 35% to 60%. A recom-mended value is 40%. Here too the “Delay Timer” setpointwill require that the lead compressor’s operating amps beequal or less than the setpoint value for the programmed“Delay ” time.

Because either compressor can be the “Lead” unit, thethree values must be set the same in each MicroTech chillerpanel.

AUTOMATIC STARTUPIf the lead compressor has shutdown and is inoperativebecause of a fault, the LLLB controller will automatically startthe other machine. No operator changeover is required.

LOAD BALANCEWhen both units, or compressors, are operating, the controllerunloads the compressor drawing the greatest % of amps un-til the % of amps drawn by both are within 5% of each other.

At any given load, as the one compressor is unloaded, thesecond is loaded to achieve the balance and satisfy the set-point water temperature.NOTE: Clock schedule and hex switches must be set in ac-cordance with earlier instructions.

IM 403 / Page 29

Table 14. KEY: DISPLAY SECTION

Key Key Press Sequence Display

1 .................... LEAVING EVAP=XX2 .................. ENTERING EVAP=XX3 ................. .ENTERING COND=XX4 ................... LEAVING COND=XX

Key Key Press Sequence Display

1 M O T O R O/o R L A = X X2 .MOTOR AMPS=XXXMotor

Amps

Oil7Temp’sPres’s

1234567 . .a..

........ EVAPORATOR = XX

....... SUCTION LINE =XX

......... SUPERHEAT=XX

......... DISCHARGE = XX

........ CONDENSER =XX

......... LIQUID LINE = XX

....... LIQ. SUBCOOL=XX.... COND. APPROACH = XX

1 ................ .OIL FEED TEMP=XXX2 ................ OIL SUMP TEMP=XXX3 ................ .OIL GAGE PRES=XXZ4 ................... OIL DIF PRES=XXZ

.

Hours7Starts

1 ................ OPERATION HRS. =XxX2 .................... .# OF STARTS=XX3 ................. START HRS AGO=XX

0RefrigPres’s

EVAP PRESSURE = XXZCOND PRESSURE=XXZ

LIFT PRESSURE=XXZ

1 ( S e e k e y p a d t e x t ,2 thru 52 page 25)Data

Scrollrl l....................Unit 2 thru 8

Status

(See keypad text,page 25)

Table 15. KEY: SETPOINTS SECTION

Key Press Sequence Display

1 ................... LVG EVAP SPT=XXX2 .................. RESET LVG SPT=ZZZ3 ................. RMT RESET SIG=XXX

Key Key Press Sequence Display

1 ( T u r n s O F F d i s p l a y )(Cancels Password)

1 ( I n c r e a s e s setpoint v a l u e sor changes statements)

1 ( D e c r e a s e s setpoint v a l u e sor changes statements)

1 ( E n t e r s n e w setpoint v a l u e sinto the software memory)

Maxrl 1

Amp2 . .

Limit 3..

MAX AMP LIM=XXX. ..___.___.... REMOT AMP LIM = XXX. ...__..___,,, REMOT AMP SIG =XxX

1 SOFT LOAD AMP=XXX2 . . BEG. AMP LIM=XXX3 RAMP UP TIME=XXX

(See keypad text andseparate schedule,pages 27 and 32)

1 . . . . . . . . . . ..__..

2 thru 49

Page 30 I IM 403

Table 16. KEY: SERVICE SECTION

Key Key Press Sequence Display

l................. [+I LOAD, [-I UNLOAD(See text, page 27)

q 1 NOW=ZZZ-ZZZFault 2 . . L A S T = Z Z Z - Z Z Z

History 3 thru 9 (See keypad text,page 27)

1 CLEARING THIS FAULT

1 (Starts the unit as the“Local” start mode switch)

KEY: Set-up

c

Options

Table 17.

Key Key Press Sequence Display

12 thru 18

12 thru 13

Changen 1

Pass-word

1

RESET OPTIONS = 222MAX. CHW RESET = Xx.X

ENT EVAP. SPT = Xx.XENT EVAP TIMER = XXZ

START MODE = ZZZ

START UP D-T = Xx.X

SHUTDOWN D-T = Xx.XSTART-START = XXZ

STOP TO START = XXZ

LOAD DELAY = XXZCOND PUMP TMR = XXZ

TWR STG 1 ON = XXZ

TWR STG 1 OFF = XXZTWR STG 2 ON = XXZTWR STG 2 OFF = XXZENABLE LAG = XX%

DISABLE LAG = XX%

DELAY TIMER = XXZ

(See keypad text andseparate schedule,page 28 and below)

(See keypad text andseparate schedule,pages 25 and 33)

(McQuay Service phone number)

(McQuay Service phone number)

N/A, 0°F mmimum to 15°F maximumNONE, ENT. CHW. AMP, AMPENT, AMPCHW

N/A, 21 ‘F minimum to 70°F maximum.N/A, 2 minute to 60 minute maximum

Local, Remote

1 “F minimum to 10°F maximum

3°F minimum to 10°F maximum20 minutes to 60 minute maximum

3 minutes to 20 minutes maximum

15 seconds to 240 seconds maximum

5 seconds to 240 seconds maximum

45 PSID to 55 PSID maximum35 PSID to 45 PSID maximum50 PSID to 60 PSID maximum40 PSID to 50 PSID maximum

60% to 100% maxlmum

35% to 60% maximum

1 minute to 10 minute maximum

P means a Password is required. TMR means Tamer

TWR STG means “Tower Stage” and refers to the cooling tower fans. If the fan control clrcult includes one or two fan cycling control relay(s), the relay(s) may

be energized and de-energized by “Set-up Options”. Keypress 12 and 13, and 14 and 15 through the solid-state output relay circuit.

IM 403 I Page 31

KEY:Clock

Sched-ule

Current Time = XX:XX (Hrs):(Min)

Override (Hrs.) =X.XHour Now, O-23 = XXMmutes, O-59 = XX

Seconds, O-59 = XXDay Of Week = ZZZMonth, l-12 = XX

Date, l-31 = XX

Year, O-99 = XX

Sl First Day = ZZZ

Sl Last Day=ZZZSl Start Hour = XXSl Start Min. = XX

Sl Stop Hour = XXSi Stop Mm. = XX52 First Day = ZZZ

52 Last Day = ZZZ52 Start Hour = XX52 Start Min. = XX

52 Stop Hour = XX

52 Stop Min. = XX#l Holiday Month = 1

#l Holiday Date = 1

#2 Holiday Month = 1#2 Holiday Date = 19#3 Holiday Month = 2#3 Holiday Date = 16

b4 thru #14 Holiday Months & Date

clO F F Sunday. Monday, Tuesday, etc

Frn Sat, etc.O-23 Hours

O-59 Mrnutes

O-23 HoursO-59 Minutes

Off, Sunday, Monday, Tuesday, etc.

Fn , Sat , etc.

O-23 HoursO-59 Minutes

O-23 Hours

O-59 Minutes

0 or 1 (Drsable, or New Years Day)0 or 1 (Drsable, or New Years Date)

0 or 1 (Disable, or Martin Luther King Jr. D0 or 19 (Disable, or Martin Luther King Jr. 1

0 or 2 (Drsable. or Presrdents Day)

0 or 16 (Disable, or Presidents Date)See Table 19 for Hokday programmed

39late)

Table 19. Holiday’s Scheduled

NOTES:

P = Password is requrred to change values

X = Indicates numerrcal values

ZZZ = Indicates alphabetical display

LlOFF = Principle disabling function to negate all time schedule control

SPECIAL NOTE:

If the system involves two compressors on one umt, or two or more umts. using a Lead/Lag-Load Baiance control module, the clock schedule setpoint “Sl-First

Day” (10th press of the keypad), must NOT be “OFF”. “Si-Frrst Day” must be set for any day 0’ the week.

Page 32 I IM 403

KEY:

Table 20.

: 22 1 SP HIGH SUCT OFF = XXX lOO”Fto200 F 125°F +

13 SP 1 HI COND PRES = XX2 1 100 PSI to t60 PSI 140 PSI 1 +

NOTES:

SP means Service Password LP means Low Pressure SPT means Setpoint

Default Setting IS the factory input setting. Default pressure values are R12: for MOO. use pressures equal to the saturated temperatures of the 1312 pressures.

Press 5-“Low Oil Delta” IS the temperature difference required above saturated refrigerant suction temperature to permit the chiller to start. If the dif-ference between actual oil temperature, and saturated refrigerant temperature is less than the input setting, the unit will not start.

** This valve is automatically set equal to the sum of 10°F plus the Low Oil Delta Temp (Press 5) plus the saturated refrigerant (Evap.) temperature.

Trip conditions are displayed by a minus or plus sign, indicating that the control will trip as the %, temperature, or pressure goes below (-), or goesabove (+) the control setting.

4 The Hot Gas Bypass setpoint does not define a safety trip devrce, but an operating control If used, the Hot Gas Bypass solenoid WIII be energized atand below the percent RLA setpoint.

IM 403 I Page 33

Figure 26. Typical Communications Interconnections.

OPTIONAL 4-20mAdc EMSSIGNAL FOR RESET OF

CHILLED WATER

OPTIONAL 4-20mAdc EMSSIGNAL FOR DEMAND “.’

PC DOS/MS DOSCOMPATIBLE COMPUTERWITH McQUAY SOFTWARE

7i RS-232C 9600 BAUD

LIMITING 1 :

MICROTECH UNITCONTROLLER #l

MicroTech____-

11: RS-485 9600 BAUD

! ADDRESS: ADDRESS:DISPLAY ENGINN 01 DISPLAY ENGINN 02: CONTROL ENGINN 01 CONTROL ENGINN 01

DISPL;

PORT B

MICROTECH SYSTEMCONTROLLER (LLLB PANEL)ADDRESS 00

MICROTECH UNITCONTROLLER #2

: RS-232C 1200 BAUD

PHONELlNi

OPTIONAL FACTORY

INSTALLED MODEM

NOTE: Maximum distance forRS-232C is 100 feet and 5000feet for RS-4851422.

RS-232C 1200 BAUDTWISTED PAIR CABLE

PC DOS/MS DOSCOMPATIBLE COMPUTERWITH McQUAY SOFTWARE

Page 34 I IM 403

SERVICE

PROTECTIVE CONTROL TIME CONSTRAINTSOperation of the mechanical low pressure switch (MLP), highpressure switch (MHP), and oil pressure differential switch(OD) serve to instantly shutdown an operating machine ifvalues in the open range of those shown in Table 12 occur.Operation of motor overloads, and other safeties wired inseries with the MCR coils, and Surgeguard and Guardistorrelay operation also all result in instantaneous trip.

To prevent nuisance tripping from fluttering flow switches,or delayed interlock closure, devices connected to terminals7,8, 9, 10, 11, and 12 on TS1 terminal strip have a built in timelag of 1.7 to 3.1 seconds prior to operation of a shutdown. Ob-viously, if a motor overload trip occurs, the protection is in-stantaneous, because the contacts are in the main MCR coilcircuits. The readout display is delayed because of the loca-tion of the logic in the time delay circuit.

SIGNAL CONVERTERThe McQuay furnished signal converter accepts a zero to

5, 6, or 7 volt AC signal and converts it to a zero to 4 volt DCsignal.

If the converter should fail and pass AC volts to theMicroTech terminal strip, TS4, the unit will trip off, and thedisplay will signal a “Mtr Current Fault”.

If the signal converter fails “Open”, the display will read“Waiting High Amps”.

WATCHDOG PROTECTIONThe MicroTech panel includes two microprocessors, in theDisplay EnGinn mounted on the keypad door, the other in thelogic cartridge mounted on the mother board.

Each of these two components has a blinking LED thatblinks independently of one another.

A third light marked “Microprocessor Status” on the keypaddoor blinks in union with the control EnGinn LED silently pro-claiming normal or troublesome operation to passersby.

The two microprocessor circuits are connected through thedaughter board to a protective circuit that keeps watch overthe operation of both.

In the event a malfunction occurs in either of the twomicroprocessors, the watchdog circuit instantly removes+5VDC power to the output board, thereby de-energizing alloutputs. This action immediately shuts down the chiller.

If the control EnGinn microprocessor fails, indicated by thecontrol EnGinn LED being constantly “on” or “off” but notblinking, the chiller can not be run until the cause of the failureis corrected.

In the event the problem is caused by the display EnGinnmicroprocessor, indicated by the display EnGinn LED beingconstantly “on” or “off” but not blinking, the control panelmay be de-energized, the watchdog circuit de-activated, andthe unit allowed to operate temporarily if necessary withoutthe display EnGinn operative.

To turn a chiller back on with a bad display EnGinnmicroprocessor,

Trip the 3 amp circuit breaker, or otherwise de-energizethe control power to the panel.

Remove the watchdog jumper from the daughter board(See Figure 27).

Disconnect the communications lead linking the twomicroprocessors together. Unplug the lead at the Port Aconnection on the inside of the door.

Re-apply the power to the control panel.

After power has been re-applied, the unit will start if it hadbeen programmed for remote control; but not without fur-ther control refinement if the unit control was on “Local”,

With the keypad and display initially programmed for“Local” control, and the display EnGinn inactive becauseof a malfunction, the keypad cannot be operated to startthe chiller. The display panel must be replaced immediate-ly, or a portable computer with IBM capability andMicroTech software connected at the communications PortA on the control EnGinn.

Another option exists if the unit is equipped with atelephone modem. The unit may be called over phonecompany lines and instructions phoned via an IBM com-patible and MicroTech software.

Because the avenues available to return a chiller tooperating status are more cumbersome if the keypad anddisplay are programmed for “Local” control, we recom-mend that the unit be programmed for “Remote” and ajumper or toggle switch wired across Field Connection ter-minal strip terminals number 9 to 64 (or 65) if a conven-tional remote switch is not planned.

WATCH DOGJUMPER

Figure 27. Daughter board showing Watchdog Jumper

DAUGHTER BOARD GROUND WIRE DIODEDaughter board terminal strip TS2 should have a diode, con-nected across terminals 1 and 8. This diode is standard onMicrcTech panels manufactured on or after April 1, 1989, serialnumber 5UDXXXXX. Panels manufactured before April, 1989,will not have this diode and it must be added during a routinevisit to the job.

This modification consists of installing a standard Surgegarddiode, part number 350A034H04, across terminals 1 and 8on terminal strip TS2. To install the diode, remove jumper wire605 from terminals 1 and 8. Connect the cathode (banded)end of the diode to terminal 8 and the other end to terminal 1.

This modification will help prevent many potential daughterboard failures and prolong the useful life of !he board.

IM 403 I Page 35

OIL GAUGE TRANSDUCER (OGT)The oil gauge transducer is a zero to 300 PSI input, 1 to 5volt DC output LVDT type transducer. The device is poweredby a 17 VDC unregulated power supply from the daughterboard and produces a linear 1 to 5 volt DC as output as thepressure is increased from zero to 300 volts.

The transducer senses gross oil pressure (saturated suc-tion plus oil pressure). Actual, or net oil pressure is the grossoil pressure minus the saturated refrigerant suction pressureas calculated from the refrigerant saturated suctiontemperature.

At 150 PSI gross oil pressure, the transducer should deliver+3 VDC to the TS4 terminal number 11 on the daughterboard.

If the DC voltage varies appreciably from the linear curveas depicted in Figure 21, the transducer may be bad and re-quire replacement.

If the DC voltage equals 4.9 to 5.0 volts, the unit will shut-down, and the display will read “Off: Oil Gauge Sensor”.

Since the DC voltage output from the transducer is a func-tion of oil pressure into the device, check the oil pressure withservice gauges before condemning the transducer.

Bear in mind also that during pre-lube, with a high stand-by refrigerant pressure, gross oil pressure will be much higherthan may normally be expected with the chiller running.

If pressures permit, adjust the oil pressure relief valve tolower actual oil pressure, and the resultant DC voltage signal.

Table 21: O-300 PSIG

ACCURACY (% Full Scale @ 25C)l Repeatibility: ~0.3% max., +O.i% typtcall L i n e a r i t y : . * 0.3%, * 0.3% typicall Hysteresis:. *i.O% m a x . , iO.5% t y p i c a l

M A X I M U M P O W E R R A T I N G : . .0.125 w a t t s

R E S P O N S E T I M E : . .less than 15 milliseconds

OPERATING TEMP. RANGE: - 4 0 l0+125”C

TEMPERATURE SENSITIVITY OVER ABOVE OPERATINGR A N G E : . _tO.l%/“C m a x i m u m

T O T A L R E S I S T A N C E : . .l K - o h m s

OUTPUT SIGNAL AMPLITUDE:. spans available to 60% of supplyvoltage

ACCELERATION EFFECTSl Acceleration-induced error under worst case conditions (In

longitudial ax is wi th gas medium): . *0.1%/g @ 60 Hzl Contact lift under conditions defined above:. none detectable

Figure 28. Oil Gauge Transducer

WIRING

0 100 200 300

PSI (INPUT)I

SENSORSWith the exception of sensors numbered 11, 12, and 13 theomission or the failure of analog sensors connected to thedaughter board terminals TS3 and TS4 will be discerned bythe microprocessor as a fault. The unit will shut down andthe faulty sensor will be identified in the MicroTech display.

This presumes that the fault exceeds pre-programmed limitsin the software. For example, if any of the eleven (11)temperature sensors short, or open, their electrical resistancewill instantly trigger a service shutdown.

If on the other hand, one of the sensors becomes erratic,or erroneous in reflection of a temperature value, this abera-tion will only be apparent following analysis of the chiller’soperating data. In the event a temperature sensor is suspect,the electrical resistance at known temperatures may be check-ed in comparison to the “Resistance vs. Temperature” tableincluded.

Sensors 11, 12, and 13 also will produce an equipment shut-down and identifying display if these sensors fail. Unlike thethermistors, however, each of these decay to zero when thechiller is off; and sensor number 11 (the Reset signal) mayremain at zero while the chiller is running without trigging afault indication.

Sensors numbered 12 and 13 must signal more than zerowhile the unit is running, and less than a pre-determined max-imum to prevent a fault statement and a trip.

Page 36 / IM 403

Table 22. MicroTech Thermistors Resistance vs. Saecified Temaerature

Q!um

15 16.10416 15,62717 15,lbh18 14.72019 14.28820 13,87121 13,46722 13,07623 12,69824 12.33325 11,97926 11.63627 11,30428 10,98329 10,67230 10,37131 10,07932 9.79733 9.52334 9,25835 9,0023b 8.75.x37 8,51238 8,27839 8,05240 7,83241 7,61942 7,41343 7,21344 7,01945 6.83146 6,64847 6,47148 6,29949 6,13350 5.97151 5,81452 5,66253 5,51454 5.37155 5,23156 5,09657 4,96558 4,83859 4,71460 4,59461 4,47762 4,36363 4,25364 4,14665 4,04266 3,94167 3,84368 3,74869 3.65570 3,565

?l727314757b777879x0Xlc1’isix48.58h87X889‘xl‘,I9293940.506979899

I( )(I101102103104105lob107108109110111112113114115116117118119120121122123124125126

Yhms

3,477 I,‘73.3V2 12x3.w IN7.228 IX)3.1Y) 1313.074 I323.om IA32.927 I 142.857 1352.7SV 1 k>2.72 3 Ii72.tl.% 1 1x2.w 1 102,34 1402,474 1412.4 16 1422.360 1432.30 1442,251 1452.190 1467.149 1472,099 14X7,051 14’)2,004 1.3)1.959 II1.914 1521.871 I531,829 141.788 1551.747 1%1.7l)X 1571.670 IS1,633 1%1.5v7 IfJO1.562 I(1 11.528 1621.494 1fl.l1,461 lb41,430 Ih1,398 1661.368 1071.339 16X1.310 ItI’)1.282 1701.254 1711,228 1721.201 17J1,17tl 1741,151 1751.1’7 l7rl1,103 177I .( )SO 17x1.058 1791.036 ISO1.0 14 181

993 182

“E183 333184 327185 321186 316187 310188 305189 299190 294191 289192 284193 280194 275195 270196 266197 261198 257199 252200 248201 244202 240203 236204 232205 228206 225207 221208 217209 214210 210211 207212 204213 200214 197215 194216 191217 188218 185219 182220 179221 176222 173223 171224 168225 165220 163227 160228 15822v 155230 153231 151232 148233 146234 144235 142236 139237 137238 135

IM 403 / Page 37

SOLID-STATE RELAY SWITCHESRecommended Testing ProcedureSolid-state relay switches may be depicted as shown in theMcQuay schematic wiring diagram; de-energized, with con-tacts open. The contacts are not ‘open’, however, in the sensethat conventional electrical-mechanical relays open theircontacts.

When energized, the relay ‘contacts’ lower their resistanceand pass current freely. De-energized, they create a barrierto current flow; but permit voltage to exist at downstream ter-minals under certain conditions.

If for example, a voltmeter is used to test Logic output relaynumber 14, with power applied to L1 and L2 terminals, andthe 3 amp circuit breaker ‘closed’, the voltmeter will display115 volts AC when connected to terminal 30 on the relay andL2. Similarly, if the relay is de-energized and the SW1 switchor oil pump auxillary contacts open, a voltmeter connectedbetween terminal 29 on the relay and L2 will also display 115volts.

On the other hand, if a test light, or a relay coil, such asthe oil pump contact coil (OP), chilled water (CHWR) or con-denser water (CWR) pump relay coils are permanently con-nected to the downstream relay terminal and to ground, avoltmeter connected between the solid-state relay’sdownstream terminal and ground, will not display any voltageThe absence of a voltage reading in this case is due to thefact that the voltage is being bled off to ground by the con-nected load.

A thorough understanding of this departure from thecharacteristics of conventional relays is required to permitprompt and accurate service analysis.

Each solid-state output relay used in the MicroTech controlpanel is equipped with its individual 5 amp fuse. Fuses resem-ble tiny resistors, and are located directly above the relay theyserve on the relay base. Fuses are pressed into place, andcan be removed by lifting them out with needle nose pliers.

Note the location of the fuse in the wiring circuit. Considerits location and the characteristics of the solid-state relay whenelectrically testing the circuit for a fault.

The LED present in the solid-state relay base responds tothe relay’s optically isolated “coil” circuit. If the LED doesn’tglow, the relay probably is not being energized. Relays re-quire the existance of 5 VDC to initiate closure. When the relayis energized, the LED should glow.

Solid-state Relav Board.

FUSE(TYPICAL)

SOLID-STATERELAYS

INPUTCONTROLPOWER5VDC

Page 38 I IM 403

Table 23. Trouble SvmDtom Ch

OUT

OUT

OUT

OUT

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

OUT

BLINKING

BLINKING

ON CONSTANT

BUT DIM

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

OUT

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLINKING

BLANK

NORMAL

NONSENSE

TRIP

STATEMENT

NONSENSE

“MCR OFF”

WAITING LOWAMPS

“HIGH MOTORAMPS”

“OIL GAUGESENSOR”

“WAITING FOR

LOAD”

OUT

OUT

ON

OUT

ON

ON

ON

ON

ON

UNIT OFF LOGIC CARTRIDGE (2)MOTHERBOARD (1 & 2)DAUGHTER BOARD

FUSE BLOWN (4)TRANS 3 FUSIBLELINK BLOWN (5)

SOME ON TRANS 2 FUSIBLESOME OFF LINK BLOWN (3)

DISPLAY ENGINN BAD (9)ON MICROPROCESSOR

LED BAD (5)SOME ON LOGIC CARTRIDGE (2)UNIT OFF

TRIP STMT DAUGHTER BOARDDISAGREES DEFECTIVE (3)W/LED IND.LED IS DIM 1

O N 1 HEX SWITCH SETTING (7)UNIT RUNS

O NUNIT OFF

SOME ONSOME OFF

OIL PUMP

RUNNING

UNIT OFFSOME ON

TS4, TERMINALS 7 & 8

OPEN CIRCUIT AT TS4

JlSOME OFF OGT ABNORMAL (‘3)UNIT OFF OIL PRESS. TOO HIGH ( 1 3 )

OGT DEFECTIVE (13)SENSOR TO DAUGHTER BOARD

* Output relay LED’s light when the relay coil circuit is instructed to energize, if there is a source of 0 and +5 VDC at the - and + terminals at the bottom

of the terminal strip.

** The Control EnGinn consists of a Logic Cartridge, a Power Cartridge and a mother board.

Table 24. Control Fuses.

IM 403 I Page 39

TEST PROCEDURE - TROUBLE ANALYSISNumbers below coincide with numbers shown in the righthand column of the Trouble Symptom Chart.

System or chiller operating problems are not described.Check the MicroTech display and fault history, or see the IMfor the unit involved for chiller problems.

All of the following assumes that power is applied to theMicroTech Station panel and the circuit breaker is on.

Where the following procedures describe the removal andreplacement of fuses, connectors, terminals or jumpers,always shut off the power to the panel before making thedisconnect or replacement.

1. If the control EnGinn LED is out, or if the LED is on butdoes not blink, check for the presence of 17 VDC enter-ing the control EnGinn, and for 5 VDC leaving. Voltagereadings should be measured by connecting the powerlead of the voltmeter to the appropriate solder plug onthe mother board, and the common meter lead to theground screw in the control back panel.Solder plugs to be tested are approximately 1 inch in fromthe right hand edge of the mother board, and in the ap-proximate vertical center.One solder plug is to the left of the words “12 VAC”. Thisplug should read, 17 VDC. Directly above this plug isanother marked “5 VAC”. A test at this plug should show5 VDC.

If the lower plug test delivers a reading of 17 VDC, andthe upper test plug shows less than 5 VDC, the problemis either in the power cartridge or the mother board.Substitute a new power cartridge for testing before replac-ing the mother board.

2. If the test above confirms the presence of 17 VDC enter-ing the Control EnGinn, and 5 VDC leaving, the problemwill probably be either a faulty logic cartridge, or a badmother board. Substitute a new logic cartridge beforereplacing the mother board.

3. To test for a blown fusible link in the #2 transformer, withthe circuit breaker tripped off (white sleeve showing),disconnect the red striped yellow lead from the terminalnumber 85. Re-apply power, and check for 12 volts ACbetween the exposed end of the red striped yellow lead,and terminal number 83 or 84.

If no voltage is indicated, verify that the meter is func-tioning or that the transformer is otherwise deliveringpower by reading between terminals 83 and 84. (Read24 VAC).

Replace a defective transformer.

4. To test the daughter board fuse, read 17 volts DC bet-ween the left side terminal clip at the fuse outlet and theback panel ground. If no voltage is present, move thepower test lead of the meter to the right side fuse clip.

If 12 volts DC is present at one end of the fuse, and0 to 1.9 volts at the other, the fuse is bad. Replace it.

If no voltage is present to ground on either side of thefuse, or very low voltage exists on both sides, check thetransformer #3 fusible link (See #5, below).

If the transformer fusible link is okay and no voltageor very low voltage exists on both ends of the fuse, thefuse is okay, but the daughter board may be bad. If so,replace it.

5. To test the transformer #3 fusible link, interrupt the powerto the panel and lift the TS2 terminal strip off the daughterboard pins. Re-apply power to the panel, and measurefor voltage between TS2 terminals #2 and #4, or #3 and#4. Voltage should read 12 VAC If it does not, replacethe transformer.

6. The daughter board contains 12 LED’s to visually depictclosure of the multiplexed digital inputs. Figure 30, page42, lists these safety devices and the LED number assoc-

7.

8.

9.

10.

iated with each.If a daughter board LED is lit, yet the display statement

shows that contact to be open, it’s possible that thedaughter board itself may be bad. To check the daughterboard, using a DC voltmeter, read the voltage across thedaughter board capacitors (mounted below LED’s). If theLED is lit, voltage should approximate 30 VDC. If the LEDis out, voltage should be zero.

If widely different values are present, before condem-ning the daughter board, check to be sure a diode, partnumber 350A034H04, has been installed between ter-minals 1 and 8 on terminal strip TS2. If not, add this diodefollowing the instructions on page 35 (“Daughter BoardGround Wire Diode”). Then retest the voltage at thecapacitor. If the voltage is still not correct, check the diodeand replace it or the daughter board.

Hex switch settings must be correct for the combinationof equipment connected. See the text and Table 11 in themain body of this IM.

The microprocessor LED located on the keypad coveris replaceable. See Replacement parts data for the cor-rect part number.

To check a suspected bad display EnGinn, interruptpower to the panel then disconnect the power plug fromthe top right hand side of the display EnGinn. Re-applypower to the panel. Read the voltage at the plug.At the plug pins 3 to 2, read 12 VAC.At the plug pins 3 to 1, read 12 VAC.At the plug pins 1 to 2, read 24 VAC.

If readings are not as described, replace transformer#2.

If readings are as described, interrupt power to thepanel and reconnect the power plug to test for 5 voltsDC to ground. Re-apply power to the panel. A test voltageconnection may be made at the 5 volt DC solder plugon the right side of the display EnGinn directly above thecommunications cable port.

If 5 volts DC is not available, replace the DisplayEnGinn.

If a replacement is not immediately available, it’s possi-ble that the chiller may be operated with a minor controlmodification. See the text describing the watchdog circuit.

Control panels with software versions number 07 and later(see software identification information) require aminimum amps consumption, following the 30 second“MCR is on” starting sequence. The minimum ampsdraw will be between 5% and 15% of compressor RatedLoad Amps (RLA) and if unchanged from the factory set-point, will be 10% of RLA.

If something in the MCR circuit, not included in theMultiplex digital inputs (daughter board LED) circuits,prevents the MCR coils from energizing, the display mayassume the MCR coils were energized, but because ofthe low current measured, scheduled an orderlyshutdown.

If this circumstance occurs, inspect those devices orconnections not overseen separately. These include thefuses in the number 14 and number 3 output relay cir-cuits, the relays themselves, the MCR coils and intercon-necting 115 VAC control wiring.

To test the solid-state relay fuses, with the LED “off”,disconnect the lead at the odd numbered relay terminal.Using a voltmeter read AC voltage from the oddnumbered terminal to ground. Voltage read should be thesame as the reading from the even numbered terminalto ground.

If no voltage is read from the odd numbered terminalto ground when voltage is applied to the even numberedterminal, and the one lead is disconnected as noted

Page 40 / IM 403

above, the fuse is probably bad. Remove the fuse andtest with an ohmmeter.

NOTE: The solid-state relay number 3 is in series withthe relay number 14. In order to make the test describedabove for relay 3, close the keypad panel switch SW1and temporarily jumper the Oil Pump contactor’s normallyopen auxillary contact (terminals C to NO). Relay 14’s oddnumbered terminal should be connected to lead 503, butlead 309 should be disconnected at the odd numberedterminal of Relay 3.

If the above described circuit also includes a set of nor-mally open (N.O.) high pressure (HP) relay contacts, tem-porarily jumper these contacts to complete this test.

Conclude the test described above.

11. If the compressor motor has been shut down by opera-tion of the controlling thermostat, or by opening eitherthe remote, or local switch, and high amperage remainsimpressed at Analog sensor terminals number 9 and 10,the oil pump control will interpret the high amps as in-dicating that the compressor motor is still running. Theoil pump will continue to run. The circumstances will alsoprevent the compressor from restarting until the problemis resolved.

This condition will occur if the signal converter DC cir-cuit fails “open” while the unit was operating.

Check the signal converter-to-analog terminal strip wir-ing and circuitry.

If the signal converter fails in such a manner as to passAC volts to the microprocessor the unit will shut downand the display will signal a motor current fault.

12. If AC volts is accidently introduced into terminals number70 and 71, this condition also will cause microprocessorto see “High Amps” and the operating results will besimilar to those described in paragraph 11.

13. See the text and Figure 28 concerning the Oil GaugeTransducer operation.

14. “Waiting for Load” will not normally indicate a hardwarefault. It could, however, be caused by an inadvertent con-trol setting. If operating conditions seem to warrant chilleroperation, but the machine has not started, review thecontrol set-up options with particular emphasis on reset.

15. Wiring from the sensors to the daughter board terminalstrip is composed of stranded, 18 AWG and 22 AWG wire.Tiny strands may project beyond the terminal to acciden-tally touch adjacent ground circuits.

No special instruction is required to check wiringintegrity.

IM 403 / Page 41

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PRODUCT WARRANTY

SnyderGeneral Corporation, hereinafter referred to as the“Company,” warrants that it will provide, at the Company’soption, either free replacement parts or free repair of com-ponent parts in the event any product manufactured by theCompany and used in the United States proves defective inmaterial or workmanship within twelve (12) months from in-itial startup or eighteen (18) months from the date shippedby the Company, whichever comes first. For additional con-sideration, SnyderGeneral Corporation warrants that for four(4) years following the initial warranty period it will provide,at the Company’s option, free replacement parts for the motor-compressor, or, free replacement for any integral componentof the motor-compressor which proves defective in materialor workmanship. For an additional consideration, the Com-pany warrants that for nine (9) years following the initial war-ranty period it will provide free replacement of the heat ex-changer in gas-fired or oil-fired furnaces which proves defec-tive in material and workmanship. (Extended warranties formotor-compressors and heat exchangers are not applicableunless separately purchased.)

To obtain assistance under this parts warranty, extendedmotor-compressor warranty, or extended heat exchanger war-ranty, simply contact the selling agency. To obtain informa-tion or to gain factory help contact SnyderGeneral Corpora-tion, Warranty Department, I? 0. Box 1551, Minneapolis, MN55440, telephone (612) 553-5330.

This warranty constitutes the Buyer’s sole remedy. Itis given in lieu of all other warranties. There is no impliedwarranty of merchantability or fitness for a particular pur-

pose. In no event and under no circumstances shall theCompany be liable for incidental or consequentialdamages, whether the theory be breach of this or anyother warranty, negligence or strict tort.

This parts warranty and the optional extended warrantiesextend only to the original user. Of course, abuse, misuse,or alteration of the product in any manner voids the Com-pany’s warranty obligation. Neither the parts or extended war-ranty obligates the Company to pay any labor or service costsfor removing or replacing parts, or any shipping charges.Refrigerants, fluids, oils, and expendable items such as filtersare not covered by this warranty.

The extended warranties apply only to integral componentsof the motor-compressor or heat exchanger, not to refrigerantcontrols, electrical controls, or mechanical controls, or tofailures caused by failure of those controls.

Attached to this warranty is a requirement for equipmentcontaining motor-compressors and/or furnaces to report start-up information. The registration form accompanying the pro-duct must be completed and returned to SnyderGeneral Cor-poration within ten (10) days of original equipment startup. Ifthat is not done, the date of shipment shall be presumed tobe the date of startup and the warranty shall expire twelve(12) months from that date.

No person (including any agent, salesman, dealer ordistributor) has authority to expand the Company’s obligationbeyond the terms of this express warranty, or to state that theperformance of the product is other than that published bySnyderGeneral Corporation.

SnyderGeneral13600 Industrial Park Blvd PO Box 1551, Minneapolis. MN 55440 (612) 553.5330

@Printed on recycled paper containing at least 10% post-consumer recycled material