EDUCATIONAL FOCUS: TESTING EQUIPMENT ELEV TOR … · 2021. 3. 18. · Elevator Performance Meter (EPM). SafeTach measures 7in. x 7in. and weighs 1.2lbs. This inexpensive and easy-to-use

154 Educational Focus Compilation

EDUCATIONAL FOCUS: TESTING EQUIPMENT

Qualitative elevator performance analysis is becomingincreasingly important. Until now, elevator performance

analysis has been exclusivelywithin the domain of expen-sive ride analysis systems.These fall into two differentcategories, portable and fixedsystems. Each has advan-tages and drawbacks. Fixedsystems are limited in theirusefulness to a single eleva-tor and require costly downtime for installation or re-moval. Because they arededicated to a single eleva-tor, they are considered cost

effective only for the high-dollar installations. Portablesystems have the advantage of being useful for testingmultiple elevators, but they can also be expensive anddifficult to operate. As a result, they have limited useful-ness in the field.

Historically both of these systems required not only themeasurement tool itself but also a separate computer for ana-lyzing the data. Once performance data was acquired, theprocess of analyzing this raw data could easily consumemany valuable man hours. Because the cost of these rideanalysis tools can range well into the thousands of dollars,most companies have had to make do with less desirablemethods. But these alternate methods of elevator perfor-mance analysis are plagued with problems. They can behazardous, subjective and inaccurate. Routinely, when con-fronted with qualifying an elevator’s performance, the meas-urements would invariably come down to a “seat-of-the-pantsfeel.” With these alternate methods, speed was measured byeither using a handheld tachometer and stopwatch or by simplyeyeballing and guessing. Because rate values (g’s) and jerkcannot be measured via a tachometer or stopwatch, theywere left as unknown values. And, in most cases, it takesmore than one person to make these measurements.

One such method was to jam open the elevator doors.One person would operate the elevator in inspection modewhile using a watch to time the test. A second personwould take a measurement against the elevator car with atachometer as it moved past. Another method was to placea person on top of the elevator car. This person would observea tachometer and at the same time watch out for obstaclesas a run progressed. A second person would operate theelevator from inside the car or control room. Sometimes a third

person was required to coordinate the activity of the other twoand supervise the test. The last and most commonly employedmethod was simply to guess. All three methods are potentiallyinaccurate, hazardous and no longer necessary: As a safe,accurate and cost-effective alternative to these methods,Maxton Manufacturing has introduced the SafeTachElevator Performance Meter (EPM). SafeTach measures7in. x 7in. and weighs 1.2lbs. This inexpensive and easy-to-use device is self-contained and portable. The elevator does

not need to be removed fromservice and only one person isrequired to make an elevatorperformance measurement.

This analysis tool requires noexternal inputs. An elevatorperformance measurement isdone by simply placing Safe-Tach on the elevator floor. Whenprompted, the operator places anelevator call. As the elevator startsto move, SafeTach performsreal-time analysis on the eleva-tor ride. The internal computer

analyzes the elevator’s ride and displays the perfor-mance information in an easy to comprehend format asthe ride progresses.

The following elevator performance information isreported: high speed, high-speed time, leveling speed, level-

ing-speed time, start g (orbreakaway), accelerationg, deceleration g, stop g,peak jerk value, run time,manual stopwatch timeand alerts for any readingthat falls outside of the rec-ommended range. It alsohas a memory function forcomparing up to three dif-ferent runs.

This performance metermakes ride analysis a quick and easy one-man job to per-form. The lack of ancillary equipment to analyze the datagreatly reduces the size and cost of this system. SafeTachis supplied with a handsome padded case, adjustmenttool, instruction manual and batteries.

Written by Bill Harmon and Maxton ManufacturingTechnical Staff

ELEVATOR PERFORMANCE METER VS. RIDE ANALYSIS TOOLS

SafeTach Elevator Performance meter,shown with optional remote control,can be used inside its protective case.

Use SafeTach by placing flat onelevator car door.

Typical SafeTach data screen

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Educational Focus Compilation 155


In the year 1990, statutory inspections of elevators inGermany underwent fundamental changes. The independentthird-party inspection company TÜV SüddeutschlandEngineering Services in Munich, at that time, developeda method specifically for inspecting elevators, the so-calledADIASYSTEM (advanced diagnosis system for elevators).ADIASYSTEM is an expert system software program, installedon a customary notebook PC and is used together withparticular electronic transducers at the standard interfacesof the PC to work as an intelligent measuring tool. Thecomplete hardware is put together in an equipment kitweighing about eight kilograms. The method is protectedthrough a couple of patents and registered designs.

At the beginning, the objective of ADIASYSTEM was toprovide a modern PC-driven alternative solution insteadof the periodic load testing of elevators required in Germany.The regular inspection of the behavior and safety of anelevator under overload is most important. Loading theelevator car with up to 150% of its rated load on the onehand is troublesome and costly, and on the other handdelivers only simple yes-or-no statements. Instead of theprescribed load tests, ADIASYSTEM goes ahead with preciseand quantitative measurement. The findings gained can beeasily compared with the required values specified in codesand standards. System-inherent safety reserves that couldnot be determined so far, now can be measured withADIASYSTEM and thus give additional important infor-mation to the expert. The software converts the findingsinto figures as well as in diagrams and stores all information

on the hard disk. The results of repeated measurementscan be easily compared with former ones.

The “classical” ADIASYSTEM test procedures conductedwith an empty elevator car instead of a load test mainly con-sist of the verification of the correct setting of the progressivesafety gear (safety test), the measurement of the traction andthe re-levelling test of hydraulic elevators. These procedureswere already described in former publications in detail, sohere only the respective basic ideas will be repeated.

The safety gear test has to give evidence that the safetiesstop an elevator car with rated load within the permissiblerange of deceleration. With the ADIASYSTEM method, adata logger measures the actual deceleration of the emptycar, and the expert system calculates the deceleration forthe rated load condition. Only for that very condition thecodes and standards stipulate specific requirements. Thetechnical behavior of progressive safety gears makes surethat the deceleration forces are largely independent fromload and speed. In this test the elevator is exposed to lessstress, due to the much less kinetic energy compared witha full-load safety gear test.

As already mentioned, the ADIASYSTEM measurementdetermines the deceleration of the empty car. However,the experience shows that in many cases retardation valuesare quite high if a safety gear is activated with an emptycar. If the elevator is carrying just one or only few pas-sengers, this stop can become very dangerous. For thetime being no requirement for an emergency stop has beenspecified in the codes. To improve the safety it wouldmake sense to limit the maximum retardation for the

THE CURRENT FEATURES OF ADIASYSTEMFOR INSPECTING ELEVATORS

by Alfons Petry

How ADIASYSTEM works

Safety diagram

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empty car too; the ADIASYSTEM has been recording thataspect for many years.

The determination of the traction using the ADIASYSTEMmethod consists of the measurement of whether the adhe-sive friction between rope and traction sheave is sufficientto prevent slippage. The relevant codes specify that no slip-page must occur with 125% rated load in the car (EuropeanStandard EN81; ASME A17), respectively 150% (in accor-dance with TRA, the German Elevator Code). The conclusionsfrom a conventional load test are only the two alternativestatements “car remains stationary” or “car slips down.”ADIASYSTEM however can measure the amount of load inthe car that would exceed the coefficient of friction betweenropes and traction sheave causing a dangerous condition.Usually, insufficient traction is to be found only on a smallpercentage of elevators; however, it is a quite serious violation.As a matter of fact, current elevator drives are no longeroversized as in the past, therefore a traction measurementwill become more important in the future.

Traditionally with hydraulic elevators, the car is testedin the landings whether the hydraulic system is capable tore-level the car with its rated load. Again, ADIASYSTEMproduces that proof with an empty car, an advantage particu-larly for heavy-duty freight elevators. An electronic gauge isused to record the pressure-time-behavior of a cycle movingdown and up, and the expert system of the ADIASYSTEMsoftware calculates both the hydraulic losses and the effi-ciency, and makes the statement whether the elevator iscapable to re-level with rated load.

For more than 10 years, ADIASYSTEM is state-of-the-art testing for elevators in Germany. The method can beused on elevators of any design and manufacturer, aswell as for any speed and rated load. Particular accessoryparts are available for the latest machine-room-less (MRL)elevators of different manufacturers.

In recent years, a fundamental re-design of the ADIASYS-TEM software took place in order to catch up with thenew possibilities of today’s PCs. Real-time measurementsoriginally designed for a DOS environment had to be con-verted to a WINDOWS solution, and a new microprocessor-controlled adapter had to be developed for that purpose.Thereby, all previous transducers can still be used underWINDOWS, using RS232 or USB ports. In the near future,transducers will be re-designed to meet the latest technology,having a direct USB connection.

Since the very beginning, new evaluation functions havebeen supplemented to the ADIASYSTEM again and again.While the original first features concentrated on safetyaspects of the elevator, additional diagnostic tools wereintegrated into the software in the course of time, which didnot only cover the safety but also aspects such as quality,availability, travel comfort, etc. These new software featurestriggered new fields of application. So, ADIASYSTEM is nolonger just an inspection method applicable to statutoryperiodic inspections of elevators. Today, it is also a verypowerful tool for any kind of measurement and documenta-tion, for acceptance testing of new elevators or for anytype of approval of elevators and safety parts, for the ex-aminations of escalators and moving walks as well as forexpert opinions on any installation of vertical transporta-tion. The following examples are typical ADIASYSTEMdiagnostic tools.

The data logger that is used for the safety test can alsobe used for the measurement of any accelerations ordeceleration in a range of +/-10g, using a 12-bit-full-scale

Diagram re-levelling test

Traction measurement

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resolution and with an option of different sampling rates.The configuration of various parameters, necessary forthe respective measurement, including defined triggerconditions, can be easily adapted via the software whenconnected to the PC. As the data logger allows very highsampling rates (up to 5,000Hz), this device can providethe recording and evaluation of fast processes with highprecision. Typical applications include the recording ofemergency stops and ride comfort measurements.

Obtaining results from ADIASYSTEM’s different graphsuses the same method. As soon as two movable cursorsare set by the user, all relevant results of this measure-ment are displayed in a status window. The representa-tion of any diagram can be adjusted in many ways to therespective needs by scrolling, compressing and expand-ing. Hence, ADIASYSTEM provides an excellent procedureto generate the documentation of any measurement made.The pressure-time diagram of a hydraulic elevator isanother example that clarifies for often only the visuali-zation of a diagram permits a conclusion or identifies afaulty function of the elevator. The results of repeatedmeasurements prove the high reproducibility of themethod. So, any diagram corresponds to a fingerprint ofthe respective situation.

Any experienced user can immediately recognize theunusual pressure peaks on the pressure-time diagram,which are caused by a too narrow distance between bothguide rails. The expert user therefore can decide on suit-able countermeasures. Without conducting a measure-ment, such defects often remain undetected, leading tohigher wear and a failure sooner or later. It is obviousthat in this case the determined cause does not generatean immediate safety risk. However, long term, this effectwill cause damage. An up-to-date, modern inspection

method like the ADIASYSTEM can help to identify a widerange of non-conformities.

ADIASYSTEM offers various graphic representations andeffective possibilities to evaluate a measurement especiallywhen made with the distance/speed gauge. After recordingthe measurement, all distance, speed and accelerationvalues are simultaneously available on the screen anddisplayed as a function of time. In addition to the measuringvalues, additional information can be recorded simulta-neously, such as electric trigger signals as well as manualmarkings through keystrokes of the user. Herewith, costlyrecordings of reactions on electric control impulses, suchas delay or respond times, can be completed and analyzedin a simple manner. Speed Diagrams 1 and 2 show forexample 1) how simple it is to check the tripping speed ofan over-speed governor; and 2) how to evaluate a record-ing for the time period between the last manual markingand the first electric trigger signal.

Ride comfort measurment

Pressure-time diagram

Speed diagram 1

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they can be transmitted to the PC later, in order to draw up thedocumentation, evaluate the diagrams or to file the records.

All intelligent transducers have their own electronicmemory chips to enable an automatic recognition of theplugged sensor. The memory chip contains the transducerserial number, date and results of the last calibration andfurther information if necessary. As soon as the sensor isconnected up, the ADIASYSTEM software automaticallyreads the information of the memory chip; the transduceris identified and has to pass plausibility and validity tests.In case the valid calibration date of the transducer has ex-pired, the software will prevent further usage of this sensor.This method guarantees that only calibrated transducers areused for measuring. Thus, ADIASYSTEM has a system-inte-grated control that verifies the status of all measuring devices,a strict demand of any quality assurance system. All trans-ducers have been designed for robust field operation. The en-tire technique has proven itself through long-time use verywell. The precision of all transducers significantly exceeds thespecified requirements of the applicable codes and standards.

For years, professional experts rely on the essential infor-mation that they gain from using the ADIASYSTEM, becom-ing an indispensable aspect of contemporary evaluation ofan elevator. In the future, the utilization of the results of themodern measurements as a part of the inspection service willbecome more important for owners and maintenance com-panies, too. The TÜV Süddeutschland is planning to addthe essential ADIASYSTEM measuring results and dia-

grams to the test reports issued and togive authorized users access to that kindof information in the elevator certificatedatabase, which is already available andaccessible via the Internet.

Alfons Petry is the director of InnovativeSystems with the TÜV SüddeutschlandEngineering Services.

At present, ADIASYSTEM’s scope of application is sup-plemented, and the hardware is complemented with twonewly developed transducers. The first new device is anelectronic load cell for safety relevant measurements onpower-operated doors in compliance with DIN EN12445.The measuring range is up to 2,000N, and the features ofthat device meet all specifications of this standard.

As this transducer has a dual purpose, the secondfunction can be used for measuring masses up to4,000kg. It is a suitable tool (for example with the use ofa traction sheave clamp) to determine the masses of theelevator car and the counterweight with high precision.This feature will significantly improve the accuracy of thealready existing ADIASYSTEM feature “balance test.”

The second newly developed transducer can electronicallymeasure and record all essential physical characteristics ofelevator doors: the kinetic energy, the hitting speed and themaximum and the permanent closing force. Both new trans-ducers are to be connected to the same “intelligent” handle,designed alternatively for both on-line- and off-line-measure-ments. The handle contains its own microprocessor andpresents the results directly after the measurement on a built-in display. All off-line values remain in non-volatile memory;

Speed diagram 2

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New door gauge

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The Lat Laser JZC is an in-spection device for the cor-rect alignment of guide railsand elevator doors.Examples of ApplicationReplacement of TraditionalPlumb Line

The JZC laser instrument,together with its target dis-play and reflector components,replaces traditional plumb lineadjustments and the alignmentof guide rails using plumb lines.It belongs to the family of meas-urement lasers and is utilizedwhere vertical and horizontalreference values are required.This makes it possible to deter-

mine reference points for alignment of the guard rails aswell as the shaft doors. The JZC laser instrument isequipped with a liquid-bearing self-alignment system. Thismakes it possible to generate a laser beam aligned inplumb fashion to a vertical object.Measurement of the Deviation of Already-InstalledGuide Rails

With the aid of a target display and/or a reflector, verticaland horizontal deviations can be measured with the utmostprecision. The testing of the quality of the installation canbe carried out immediately after rail placement and alsoafter a certain period of operation. The alignment of theguide rails can change as concrete loses volume and asthe result of building settling, reducing both travel comfortand car operation safety. The erection of a reference linewith steel wire is very difficult, but with the JZC laser instru-ment, the determination of the reference values is possiblewithin a very short time. Document the installation qualityin terms of DIN EN13015 as well. Possible measurementaccuracy deficiencies can be reduced by means of a self-testing of the measurement precision of the laser instrument.The device corresponds to laser installations of Class 2and fulfills the European Standard EN60825.Featuresu Suitable for elevators in accordance with AR95/16/EG,MR98/37/EG, EN81 and TRAu Testing of installation quality with both new installa-tions and modernization projects (cf. DIN EN13015)u Measuring device for checking vertical and horizontalposition of guide rails and elevator doors

u Takes the place of the traditional plumb line procedureu Determination of the reference points in the shaft byutilization of a laser systemu Measurement of the coplanar relationship of twoguide railsu Readily recognizable laser beamu Fluid-based self-aligning system (patented)u The laser is in compliance with EN60825-1/A11:1996and EN61010-1/A2:1995 in terms of safety and reliabilityContent of SupplyTransport Case Containsu JZC laser instrumentu FJ11 target displayu Reflectoru Safety lineu Set of batteriesu Instruction handbook

Laser Instrument JZCu Accuracy: ±0.5%0 (±0.5mm/10m)u Wave-length/maximum output: 650nm/0.5mWu Class/norm: 2/EN60825-1u Laser beam/radius of action: Ø 3mm/50m, Ø 5mm/70mu Time of self-leveling: 15su Operating environment temperature: 5°C~35°Cu Humidity: <90%u Power supply: 3VDC 2St/piece AA-(mignon)u Weight (without batteries): 1.5kgu Device bag weight: 1.9kgu Dimensions: 360(B)x330(T)x17(H)mm, 360(W)x330(D)x17(H)mmTarget Display FJ11u Wave-length/maximum output: 650nm/0.5mWu Class/norm: 2/EN60825-1u Laser beam/radius of action: Ø 3mm/50m, Ø 5mm/70m

TESTING EQUIPMENTby Rainer Schmitt

Lat Laser JZC

JZC laser instrument FJ11 target display

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u Operating environment temperature: 5°C~35°Cu Humidity: <90%u Power supply laser: 3VDC 2St./piece AA-(mignon)u Digital display: 1.5VDC Knopfzelle/button cellu Power consume: <0.2Wu Weight (without batteries): 0.9kgTravel Data SensorDescription

The Travel Data Sensor is an independent microprocessor-controlled measuring device with an integrated accelera-tion sensor. The sensor measures the acceleration in avertical direction with a small side sensitivity. The integratedmodule “LIFT Checker” in LIFTCALC® offers the possibility tostore and evaluate the measured deceleration values(e.g., measurement of the travel quality during a floor-to-floor trip).Featuresu Proven documentation of the functionality and safetyof the lift installation in accordance with Lifts Directive95/16/EG (fulfills GSA) u Assessment of the travel quality of traction and hydraulicsystem u Troubleshooting in the system by vibration and oscil-lation measurements u Measurement and assessment of critical deceleratingvalues (activation of buffer, electrical emergency stop) u Complete documentation of an installation (productliability)u Data transmission from travel data sensor to PC via serialinterface; measurement listings can also be transmittedto a central location by telemetry

u Safety gear checkwhen lift is empty (Ad-justments checked inaccordance with TRAand EN)u Assessment of theacceleration and decel-eration diagrams usingLIFTCALC u Sampling frequency5,000Hz u Acceleration range±10g u Shock resistant upto 1,000gu Simple operation u Weights are not re-quired Content of Supplyu One travel data sensoru One connection cablefor PC

u One mounting strapu One plug-in power supply unitu One floppy disc u One instruction manual

Evaluation of the Travel Comfort of a SystemLift travel comfort has so far been judged only individually.

With the newly developed Travel Data Sensor, the accelera-tion and deceleration values can be directly recorded onthe lift and displayed on the screen after being read out ofthe sensor memory and can be stored on site. The diagramshows an example of the travel path of a frequency con-trolled lift with and without obstacles on the guide rails.Pressure SensorDescription

The measuring principle of the Pressure Sensor is basedon a wire strain gauge, which enables the detection of thehydraulic system pressure. The power supply of the pressuresensor is achieved via the serial interface of a PC. Themeasurement values are transmitted online to the PC andcan be displayed on the screen as well as being picturedin the form of a pressure-time diagram. These can be stored.Featuresu Proven documentation of the functionality and safetyof the lift installation in accordance with Lifts Directive95/16/EG (fulfills GSA)

Travel Data Sensor dimension (wxhxd): 95x 160 x 45mm

Normal travel path of a frequency controlled lift

Travel path of a frequencycontrolled lift with one obstacle on the guide rails

Travel path of a frequencycontrolled lift with two obstacles on the guide rails

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u Complete documentation of an installation (productliability)u System pressure check and analysis of possible pres-sure drops (leakages) u Examination of the behavior of the dynamic pressure inthe systemu Control system check (e.g., resonance, overshoot) u Testing of the anti-creep device u Adjustment of the pressure relief valve u Evaluation of the pressure-time diagram through LIFTCALCu Maximum measuring frequency 100Hz u Standard measuring range 0. . . .100 bar

u Easy to useu Weights are not requiredContent of Supply u One pressure sensoru One rapid action coupling to sensor connectoru One connecting cable for PCu One floppy disc u One instruction manualAssessment of the Pressure Behavior of a Lift Installation

The representation of the pressure behavior of a hydraulicsystem offers the user the possibility to determine abnor-malities which appear in pressure-time diagrams throughsudden pressure drops or rises (e.g., pressure increase dueto piston clamping; pressure increases due to prematureresponses of the pressure relief valve).

Rainer Schmitt is the Marketing and Sales manager with WitturAG K + S. He has worked for Wittur Germany for the last 10 years.

electricconnection for cable to PC

Connec-tion tothe valveblock

ideal travel path Clamping of the piston at threepositions

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IntroductionThe measurement of elevator ride quality (frequently called

ride comfort) has become an important subject over thepast several years. It is now often part of specificationsfor new and modernized elevator systems. It is also acompetitive issue for elevator manufacturing, installationand maintenance companies because it is a strong indi-cator of the quality of design, installation and service ofelevator systems. More than that, the analysis of vibrationand sound that has been collected for ride quality measure-ments provides the ability to diagnose the function of elevatorand escalator system components.

How ride quality is measured strongly affects the re-sults of those measurements. Based on extensive workthat was performed by companies from around theworld, a new international standard was developed forthe measurement of elevator ride quality. The new stan-dard is draft ISO 18738 Lifts (elevators) – Measurementof Lift Ride Quality. ISO 18738 establishes the require-ments, methodology and processing techniques that arerequired to standardize the measurement and evaluationof elevator ride quality, and the performance characteristicsincluding acceleration, velocity and jerk. This standard doesnot try to establish what is, or what is not, acceptable interms of ride quality. Practically, acceptability has to beconsidered a moving target. The technology and techniquesto provide “good” ride quality will change (hopefully improve)over time. Utilizing the new standard offers the ability toevaluate and troubleshoot using vibration and sound toidentify problem areas and improve ride quality. It isimportant to remember that we are not simply evaluatingvibration and sound, but the vibration and sound that relatesto ride quality (i.e., human response to that vibrationand sound). This means that we are evaluating vibrationthat was collected in a specific way and analyzed usingspecified techniques.The Vibration Record First Order Analysis – Troubleshooting

Data as collected by an instrument may, or may not, berelated to how people feel that vibration, depending onhow the data was processed. For example, Figure 1 displaysthe vibration and sound level as collected by an EVA-625,prior to processing for ride quality evaluation. Displayedfrom top to bottom are: sound level, x-axis acceleration(front to back), y-axis acceleration (side to side) and z-axisacceleration time histories. Although this is a graphical

representation of sound level and accelerometer outputs,the elevator industry generally distinguishes between accel-eration and vibration based on the net motion of the car.Figure 2 represents the data after it has been processedaccording to the new ISO standard and is used to evalu-ate elevator ride quality. This allows the direct diagnosisof problems that have a negative effect on ride quality.The data that has been processed according to the stan-dard is intended to give meaning, such that an increasein the level of vibration, corresponds to an increase in theperception of that vibration.

Although measurement and analysis provides a completestandardized evaluation of performance characteristics ofan elevator system, for the purposes of this discussion a limitedanalysis of the vibration at full speed will be made. Vibrationis characterized in terms of the maximum peak-to-peak

ANALYSIS OF ELEVATOR RIDE QUALITY, VIBRATION

by Gregory P. Lorsbach

Figure 1

Figure 2

International Services Building Elevator 23Units: milli(g) File: 5TWG3E71.VE2 10:13:15: 04/03/97


Seconds

Seconds

Run Sound: 61.5L Aleq: 57.8 Max Sound: 74.6

Run Sound: 61.5L Aleq: 57.8 Max Sound: 74.6

Max Pk/Pk: 47.3 A95: 26.5 0-Pk: 33.1

Max Pk/Pk: 9.4 A95: 4.5 0-Pk: 6.9

Max Pk/Pk: 9.8 A95: 6.1 0-Pk: 7.8

Max Pk/Pk: 20.0 A95: 14.3 0-Pk: 34.3 Jerk Zone Max Pk/Pk: 36.3

Max Pk/Pk: 29.0 A95: 15.9 0-Pk: 21.6

Max Pk/Pk: 54.3 A95: 32.2 0-Pk: 171.8

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vibration, and the A95 (typical vibration) between the pointsthat an elevator has traveled 0.5 meters (1.64 feet) fromits start position, through to the point at which an eleva-tor has traveled to within 0.5 meters (1.64 feet) of its finalposition. The units that are typically used in evaluating vi-bration are milli(g)s. Bear in mind, that vibration is a re-sult of the moving elements, as well as the control elements,that make up an elevator system.

When attempting to evaluate the function of the compo-nents of an elevator system, the first approach is to conducta first order analysis, based on a few simple questions: a. Is the vibration acceptable?b. Does the problematic vibration show up in the horizontalaxes or vertical axis?c. Is the vibration impulsive or continuous?Acceptable Vibration

As a worldwide supplier for ride quality instrumentation,I am often asked what is considered “a good vibrationlevel”? This question is not easily answered. What is accept-able from a vibration level standpoint is based on manyfactors. A primary factor is a competitive issue with respectto the expectations of the local market. Realistically, everyelevator company manufactures a system that causes abox to move up and down in response to traffic require-ments. Competitive pressures keep the cost for equivalentfunctionality approximately the same. However, the motionand sound that a rider perceives correlates with the percep-tion of the quality of design, installation and maintenance.It has been my experience that the maximum acceptablevibration level for new or modernized elevators is lessthan 12 milli(g)s maximum peak to peak, and less thanhalf that for the A95 (typical) peak to peak. It is not un-common (therefore, achievable) for the maximum peak-to-peak vibration to be less than 10 milli(g)s and the A95peak-to-peak vibration to be less than 5 milli(g)s for high-speed elevators. Certainly, there is a relationship to cost.I will often suggest that the user measure what they knowto be an elevator that they find to be acceptable. Using thatdata, they can create internal benchmarks for acceptability.Horizontal or Vertical

This is an important question since vibration sourcescan be identified based on the axis that is being affected.Knowing the axes affected allows the user to quickly elimi-nate possible vibration sources. The potential horizontalaxis vibration sources are rail misalignment and/or rolleror slide guides. The vertical axis vibration sources are ropes,sheave, machine, controller/drive or counterweight.Impulsive or Continuous

As we inspect the unfiltered x-axis time history moreclosely, with respect to distance traveled (Figure 3), it isapparent that there are a series of “bumps.” Using the EVAElevator/Escalator Vibration Analysis Tools software, it is

determined that the bumps are separated by one raillength (located at 40, 56, 72 and 88 feet from the point atwhich the elevator started). This would lead to the conclu-sion that there are misalignments at those points (one raillength apart) causing excess vibration. However, this is thevibration that is sensed by the EVA-625. When addressingride quality, it is desired to address the vibration that peoplefeel. Figure 4 shows the same record after filtering usingthe filter specified in the ISO standard on Lift Ride Quality.Clearly the signal is very different since the apparent bumpsare located at 56, 72 and 88 feet in the unfiltered data areno longer readily apparent, while the bump located at 40feet is clearly visible. This approach allows the maintenancecompany to address the vibration that a rider would feeland not waste time on vibration that people do not feel.This is an example of impulsive motion. When dealing withimpulsive vibration in the horizontal axis, it is usually safe toconclude that it is related to a specific location in thehoistway. Fortunately, the use of the EVA software allowsthe user to locate the “bumps” precisely in the hoistway.

When addressing continuous vibration, the question ofhorizontal or vertical remains important. Continuous

Figure 3

Figure 4


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horizontal vibration is either the result of something that af-fects the entire hoistway (e.g., rail misalignment) or thesource of vibration is travelling with elevator (e.g., rollers).In the most general sense, horizontal vibration sources arelocated within the hoistway or even on the car.

Some of the sources of continuous vertical vibrationare related to the ropes, sheave, machine, controller orcounterweight. Referring to Figure 5, the vertical axiscontinuous vibration is readily apparent (upper for refer-ence to show the acceleration, lower is the ISO-filtereddata that is used for ride-quality measurements). It isclear that there is a strong vertical vibration throughoutthe record. However, the vibration level greatly increasesas the elevator travels from the bottom floor to the top floor.Often to find the source of vibration, we use a powerfulanalytical tool, the Fast Fourier Transform (FFT, vibrationversus frequency) to perform a second order analysis.Second Order Analysis

When discussing continuous vibration, we are oftenreferring to vibration resulting from rotating elements (aseries of impulsive events can also be called continuous).The driving elements of an elevator have a number of ro-tating components, including the sheaves, motor andgears within the gearbox. Problems in these areas can havea significant effect on vertical vibration level and ridequality. Each of those can be characterized by a rotationalfrequency. The rotational frequency can easily be calculatedknowing the diameter of the element (direct measure-ment) and the speed of the elevator (EVA-625 data analy-sis). As an example, assuming a 16-inch sheave diameter(d) and 1,200fpm elevator (v), the rotational frequency (f)is calculated such that:

Diameter (d) = 16 inches (406.4 millimeters)Speed (v) = (1,200fpm)/(60 seconds/minute) = 20

feet/second (6.096 mps)Roller Circumference C = πd = 3.14159 x (16 inches x

1 foot/12 inches) = 4.189 feet (1.277 meters)Sheave Rotational Frequency = v/C = 20/4.189 = 4.77

rotations per second = 4.77 Hz (=̃4.75)If the FFT (spectrum) of the vertical axis vibration signal

indicates that there is significant energy at about 4.75 hertz,then we can correlate that with the sheave. It is also importantto realize that this would be the fundamental frequency

Figure 5 Figure 6

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and that some higher order harmonics may also be present(i.e., 9.5, 14.25, 19, etc. Hertz) as well. The same approachcan be applied to components such as the guide rollers.Additionally, the motor/worm/ring gear rotational frequenciesmay be identified in the vertical axis vibration signal.

A good example of using the FFT is demonstrated, againreferring to Figure 5 (500fpm, geared). It is obvious that thevibration level increases as the car travels from bottom totop. Figure 5, lower, indicates that the perception of thatvibration increases as well. The first thought while on sitewas that the vertical vibration was related to the ropes.Had this been the case, there would likely have been asignificant change in frequency, as analyzed through theFFT. If one imagines a guitar string with a constant tension,as the string gets shorter, the frequency would increase.To test this, the FFT was used to evaluate the frequencycontent of the signal at different points during the trip(Figure 6). The spectrum of the vertical axis (Figure 7),just after the elevator reaches full speed, indicates that thedominant frequency is about 26.5 Hertz. About halfwaythrough the trip, the dominant frequency is still about 26.5Hertz (Figure 8), although the amplitude has increased byabout 150%. Just prior to deceleration, nearly at the top, thedominant frequency remains at about 26.5 Hertz (Figure 9),but the amplitude has tripled. This indicates that there has

been no significant change in the frequency of vibrationas the elevator traveled from the bottom to the top of thehoistway. Using this approach, the ropes and sheave canbe eliminated. The next step was to attach the EVA-625accelerometer directly to the gearbox and make a measure-ment while the elevator was moving. Analyzing the vibra-tion signal (Figure 10), the spectrum (Figure 11) indicatesthat the dominant frequency was about 27 Hertz or nearlythe same as that measured on the floor of the car. This allowsus to conclude that the source of the vibration, and poorride quality, was the machine (gear mesh frequency).Conclusion

It is important to remember that successful field personnelwithin the elevator industry are necessarily clever andanalytical (problem solvers). Although, they may have notbeen exposed to vibration analysis as part of their educationor experience, they can apply basic and powerful techniquesto analyze vibration and quickly evaluate the condition ofmost elements of an elevator system. Further, it is a simplematter to determine if repairs or changes that had beenmade to an elevator had the desired effect of improvingride quality.

Gregory P. Lorsbach is with Physical Measurement Technologies,Inc. located in Marlborough, New Hampshire.

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EDUCATIONAL FOCUS: TESTING EQUIPMENT ELEV TOR … · 2021. 3. 18. · Elevator Performance Meter (EPM). SafeTach measures 7in. x 7in. and weighs 1.2lbs. This inexpensive and easy-to-use