Motor Protection Training Course

7/31/2019 Motor Protection Training Course

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gGE Power Management

Motor Management Relay Course


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Motor Theory


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gGE Power Management Motor Theory

A2

A1


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Two main components comprise a3 phase AC induction motor:

Rotor

Stator

A Slight air gap exists between

the rotor and stator


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Ns = 120 F

PPole # Synchronous

2 36004 18006 12008 900

10 720


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% Slip = Ns - Nr x 100 %

Ns


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gGE Power Management Motor Specifications

Starting Current:

when rated voltage and

frequency is applied to NEMA Bmotor, it will typically draw 600%of full-load current and

decrease to rated value asrotor comes up to speed

600%

100%


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Torque

Radius

Force

Torque = Force x Radius

Distance = Circumference = Radius x 2

Power = Force x Radius x 2 / Time


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Horsepower:

Engineering unit of power33,000 lb 1ft in 1 min


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Efficiency:

an indication of how much electrical energy is converted tooutput shaft mechanical energy expressed as a percentage.

Core loss

Stator loss

Rotor Loss

Friction andWindage

Stray loss

Losses

Mechanical

Energy

ElectricalEnergy

in

Electrical Energy in = Mechanical Energy out + Losses (mostly heat)

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Classes of Insulation:

Class A Class B Class F Class H

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Service Factor:

When the voltage and frequency are maintained at the values specifiedon the nameplate the motor may be overloaded up to the horsepowerobtained by multiplying the nameplate horsepower by the servicefactor.

At the service factor load greater then 1.0 the motors efficiency, power

factor and speed will differ from nameplate. But the locked rotor currentand breakdown torque will remain the same.

For a given insulation motors with a 1.15 service factor have a lower

rise then those with a service factor of 1.0. This allows the motor tooperate close to the service factor without exceeding rated temperaturelimits of the insulation. If the motor is operated at the Service factor themotor will have a temperature rise in excess of the 100% rated rise for

motors with a 1.0 service factor. This will shorten the life expectancyconsiderably.

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gGE Power Management Review: Basic Low voltage motor protection

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Information required:

Motor FLA

Locked Rotor Current

Locked Rotor Time Hot

Locked Rotor Time Cold

Safe Stall Time Cold

Service Factor

Motor damage curve

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The Motor Management Relays have threebasic categories of protection elements:

TRIPS

ALARMS

BLOCKS

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gGE Power Management Trips

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gGE Power Management Alarms

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gGE Power Management Block Starts

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gGE Power Management Thermal Modeling

Thermal Modeling:

Select O/L Curve

Determine Overload Pickup

Hot/Cold safe stall ratio

Unbalanced Bias

Cooling Times and start inhibit RTD biasing

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StartingCurrent

Ambient Temperature

Unbalanced CurrentMotor Losses

Overload setpoint

Volume

depending onmotor

Motor Cooling

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Thermal Capacity

required to start40%

Thermal Capacity Used

due to Overload80%

Thermal Capacity must

decay by 20% (from 80%

to 60% Used) in order to

start the motor

20%80%

60%{

Figure 2-1

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Thermal Modeling:

Select O/L Curve


Hot/Cold safe stall ratio

Unbalanced Bias

Cooling Times and start inhibit RTD biasing

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Typical Motor Thermal limits Curve

Thermal limit curve whenmotor is cold

Phase current in multiplies of FLC

Timeinseconds

Thermal limit curvewhen motor is hot

Acceleration curve @80% rated voltage

Acceleration curve@100% voltage

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Built in overload curves

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Thermal Limit Curves

1

10

100

1000

10000

100000

20

60

101

140

180

220

260

300

340

380

420

460

500

540

580

620

Percent Full Load

Time(secon

ds)

Motor Manufacturer's Thermal Limit

Curve

269 Plus Custom Overload

Curve

Motor

Acceleration

Curve

44 sec.

38 sec.

9 sec.

3 sec

Therefore, after thismotor has completed asuccessful start, theThermal Capacity wouldhave reachedapproximately 40%.

Figure 8.3

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Thermal Limit Curves

1

10

100

1000

10000

100000

20

60

101

140

180

220

260

300

340

380

420

460

500

540

580

620

Percent Full Load

Time(second

s)

Motor Manufacturer's Thermal Limit

Curve

269 Plus Custom Overload

Curve

Motor

Acceleration

Curve

44 sec.

38 sec.

9 sec.

3 sec

Figure 8.3

Therefore, after thismotor has completed asuccessful start, theThermal Capacity wouldhave reachedapproximately 40%.

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If a 40% TC was used tostart initially running O/Lcurve area will be reducedby 40% from that of the

cold curve area

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Thermal Modeling:

Select O/L Curve


Hot/Cold safe stall ratio Unbalanced Bias

Cooling Times and start inhibit

RTD biasing

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Thermal Modeling:

Select O/L Curve




RTD biasing

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Timein

seconds

b

d1015

c

1

a

Phase Current in Multiplies of FLC

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Thermal Modeling:

Select O/L Curve




RTD biasing

gTh l M d li


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gGE P M Th l M d li


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gGE P M t Thermal Modeling


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Thermal Modeling:

Select O/L Curve




RTD biasing



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GE Power Management Thermal Modeling

Thermal Model Cooling 80% load Thermal Model Cooling 100% load



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Thermal Model Cooling Motor Stopped Thermal Model Cooling Motor Tripped



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Thermal Modeling:

Select O/L Curve




RTD biasing



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RTD input is a indicator of the thermalcapacity used dependent on stator

temperature (very slow).

The relay will use the calculated thermalcapacity unless the RTD thermalcapacity is higher.

Figure 8.4: RTD Bias Curve Example

gGE Power Management Instantaneous Short Circuit Protection


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GE Power Management

1

10

100

1000

10000

100000

20

60

101

140

180

220

260

300

340

380

420

460

500

540

580

605

Percent Full Load

Time(seconds)

Acceleration curve (motor

current during starting)

Locked Rotor current

Motor Thermal Limit

Instantaneous

Overcurrent

Protection

Instantaneous Short Circuit Protection

gGE Power Management Ground Fault


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GE Power Management Ground Fault

Resistive Grounded System and a Inductive Grounded System



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g G ou d au t

Figure 4.2: Zero Sequence CT (Moisey, 1997)



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g

Figure 4.3: Residual Ground Fault Connection (Moisey, 1997)



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DC Offset

Figure 4.4: Asymmetrical Starting Current (GE Multilin, 1998)

gGE Power Management Phase Differential


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gGE Power Management Mechanical Jam


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gGE Power Management Undercurrent


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gGE Power Management Under Voltage


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If an induction motor operating at full load is subjected to an undervoltage condition, the following effects will occur (Moisey, 1997):

Full load speed will decrease

efficiency will decrease

power factor will increase

full load current will increase

temperature will increase

Most motors are designed close to the saturation point:increasing the V/HZ ratio could cause saturation of air gap

flux causing heating

gGE Power Management Overvoltage


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When the motor is running in an overvoltage condition, the followingaffects will occur (Moisey, 1997):

slip will decrease because slip is inversely proportional tothe square of the voltage

efficiency will increase slightly and power factor will

decrease because the current being drawn by the motor willdecrease

temperature rise will decrease because the current has

decreased (based on the formula I2t)

gGE Power Management Acceleration Timer


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gGE Power Management Soft Starter Using Autotransformer


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gGE Power Management C.T. Characteristics


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.02 ohm

.01 ohm

.03 ohm

Knee Point: The point at which a 10% increase in voltageproduces a 50% increase in magnetizing current

SecondaryV

oltage

Vk

Vf

Exciting current



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gGE Power Management AC Saturation


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Partly Saturated Sever SaturationNo Saturation

gGE Power Management DC Saturation


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Primary current

Secondary Current



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15



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ANSI Device Numbers

2 Time-delay 63 Pressure

21 Distance 64 A aratus round

25 Synchronism-check 67 AC directional OC

27 Undervoltage 68 Blocking

30 Annunciator 69 Permissive

32 Directional power 74 Alarm

37 Undercurrent or under ower 76 DC overcurrent38 Bearing 78 Out-of-step

40 Field 79 AC reclosing

46 Reverse-phase 81 Frequency

47 Phase-sequence voltage 85 Carrier or pilot-

wire49 Thermal 86 Lock out

50 Instantaneous Overcurrent 87 Differential

51 AC time overcurrent 94 Tripping

59 Overvoltage

60 Voltage balance



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gGE Power Management 239 Motor Protection Relay


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FEATURES

Status/current/temperature displayFault diagnosisTrip record

Memory lockoutThermal capacity/load %/RTD analog

output

Trip/alarm/auxiliary/service relay outputsSimulation mode for field testing

RS485 Modbus communications interfaceAC/DC control powerCompact size, fits most startersUpdate options and/or MODs in fieldCSA/UL Approved

PROTECTION

Overload (15 Selectable Curves)Short circuitLocked rotor

Stall / mechanical jamRepeated startsSingle phase/unbalanceGround faultOver temperature (Thermistor & 3

RTDs)UndercurrentOverload warningBreaker failure



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Control Latched main trip relay, alarm relay 2 auxiliary relays Emergency restart capability

Pre-trip alarm warnings Optional single-shot restartMetering and Monitoring Motor current (Amps, % full load) Motor thermal capacity

Record of pre-trip motor values Record of motor statistical data Up to 6 stator RTD inputs Four additional RTD inputs Motor ambient air temperature

Continual self-test Ground fault current Optional MPM metering of V Wvars PF Hz MWh

Application Three phase AC motors Mechanical system protectionProtection

Stator winding over temperature Bearing over temperature Multiple starts Overloads 8 standard overload curves

User defined overload FlexCurve Locked rotor Rapid trip/mechanical jam Unbalance/single phasing Short circuit

Ground fault Undercurrent Phase reversal (meter option) Variable lock-out time "Learns" individual motor parameters


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SR469 Motor Management Relay469 Motor Protection Relay


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Ordering data


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gGE Power Management SPM


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A li ti


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Applications

Collector-ring synchronous motors

Brushless type synchronous motors

Control

Field application PF regulation maximizes efficiency

Reluctance torque synchronizing Re-synchronizing Auto loading/unloading



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g GE Power Management SPM


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g GE Power Management


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g GE Power Management 239 Motor Protection Relay


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g GE Power Management 239 Motor Protection RelaySpecifications


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g GE Power Management Installation


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g GE Power Management#1


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Information required:

Motor FLA


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Motor FLA

Locked Rotor Current

Locked Rotor Time Hot

Locked Rotor Time Cold

Safe Stall Time Cold

Service Factor

Motor damage curve



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g GE Power Management Communications: Computer


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g GE Power Management Setpoint: 239 Setup


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g GE Power Management Setpoint: System Setup


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g GE Power Management Setpoint: System Setup


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Start Time Allowed = SAFE STALL TIME COLDx((LOCKED ROTORCURRENT)2 /(Actual Start Current) 2 )


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Example:

- normal inrush current is 6 x FLC- actual current inrush current was only 5 x FLC on a start- SAFE STALL TIME COLD has been set to 20 seconds

maximum start time allowed would be:

Start Time Allowed = SAFE STALL TIME COLDx((LOCKED ROTOR

CURRENT)2 /(Actual Start Current) 2 )

= 20 x ((6) 2 /(5) 2 )= 28.8 seconds



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g GE Power Management Setpoint: Protection


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g GE Power ManagementLab 1


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269 Installation


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269 Installation


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RTD Wiring


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Relay Output Wiring


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g GE Power ManagementRemote RTD Module


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369 Configuration


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Figure 4-9


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Digital Inputs


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SR469 Motor Management Relay


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User Interface

DISPLAY

40 character display

Clear messages which

do not require deciphering

STATUS INDICATORS

SR469 status

Motor status

Output relays

KEYS FOR LOCAL

CONTROL

Reset

Next (to scroll messages)

PROGRAM PORT

INTERFACE

HELP KEY

Provides context sensitive

Numeric keypad


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INTERFACE

RS232 for connection to a

computer, 9600 baud

DRAWOUT HANDLE

with provision for a wire

lead seal to prevent un-

authorized removal

messages

Control and programming

keys for complete accesswithout a computer

MAINMAIN


Specifications


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SR469 Installation


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VOLTAGE DEPENDENT OVERLOAD CURVE

Locked rotor and 100% startingcurvs very close and in somecases overlap: use voltagedependent curve to ensure no trip

and faster restarts: use less TC

1). Enter worst casecustom curve


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Figure 4-10


Figure 4-10


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Figure 4-11 Figure 4-12


Figure 4-13


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Figure 4-15Figure 4-14


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gGE Power Management SPM Specifications


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Synchronous Motor Theory


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Synchronous Motor Theory


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Figure 2


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Figure 14


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Hall Effect DC CT


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Figures 16


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Figures 17


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Figure 18


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Typical rotating rectifier exciter schematic diagram with synchronous motor.


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Communication

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LAN Protocol

Broadband

Base band

Asyncronous Transmissions

START BITData Bits Parity bit

Stop bit

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RS232

T

R

R

T

Com.

gg


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g

RS232

T

R

R

T

Com.

gGE P M


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RS485 is a balanced system:

D

R

D

R

D

R

gGE P M t


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GE Power Management

Master Request Transmission:SLAVE ADDRESS - 1 byteFUNCTION CODE - 1 byte

DATA - variable number of bytes depending on FUNCTION CODECRC - 2 bytes

Slave Response Transmission:SLAVE ADDRESS - 1 byte

FUNCTION CODE - 1 byteDATA - variable number of bytes depending on FUNCTION CODECRC - 2 bytes

Documents

Motor Protection Training Course