Telediagnose g 03 (Refrigeration Compresor)

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the condition monitoring magazine of PRÜFTECHNIK AG and Flender Service GmbH

No. 03 - March 2002

In this issue:

Teamwork in Asia

Fastest gear service for a Danishcement factory

Digital and software-supported teleservice (1)

Characteristic vibration values

Basic rules for the measurement offrequency spectra

‘Thermal’ movement of a propanerefrigeration compressor

News & Events

Condition monitoring application:

Fastest gear servicefor a Danish cement factoryDr.Becker, Herne

This was the subject of discussionsthat took place a short time ago inSingapore between Dr. Becker (FlenderService) Henry Chua (PRÜFTECHNIKSingapore) and Johann Lösl (PRÜF-TECHNIK Condition Monitoring, Isma-ning).

The know-how of PRÜFTECHNIK inequipment engineering and the integra-

tion of online solutions into an overallmonitoring strategy and the gear-speci-fic application knowledge of FlenderService - as well as the strong presenceof both partners in this region - createsan ideal situation to offer first classsystem solutions to the customers ofsouth-east Asia and China, just as inEurope.

Changed sounds from gears can be anindication of gear problems. If a crackin a planetary gear is then diagnosed bymeans of vibration diagnosis, the ma-chine must be stopped, the gear dis-mantled and a replacement found.However, who has planetary gears, e.g.for roll press gears, immediately avail-able? The fastest possible assistance iscrucial! After all, even the largest stor-age bins are emptied after a few days,and delivery times of high performancegears can be several months. HowFlender Service reacts to this situation isdescribed in the following report.

But, first things first. Mr. Cools, amarketing engineer at Flender ServiceCondition Monitoring, received a tele-phone call from Mr. B., head of the mostnortherly cement factory in Denmark.He reported that the noises coming froma grinding machine had changed, andrequested that a gear and vibration spe-cialist be dispatched. A diagnostic spe-cialist from Flender Service took a flightthe very next day, and was able to carryout noise and vibration measurementson the roll press drive in the late after-noon of the same day. The measurementresults of the loose bearing gears werenoticeable because harmonics of 6.7 Hzappeared in the envelope spectra. Noth-ing unusual was apparent in the vibra-tion velocities as shown in Fig. 2.

“How long can we continue to run?”,

was the first question asked by the sys-tem operator. In the meantime, all theexcitation frequencies of the gear hadbeen calculated in Germany. A crack in aplanet pinion of the first planetary stageof the three stage spur gear/planetary

gear was diagnosed. The machine wouldhave to be stopped. The next morning,Mr. Tillemann, a service technician atFlender Service, was on his way to Den-mark to dismantle the gear in question.Fig. 3 shows the dismantled 8

PRÜFTECHNIK and FLENDER SERVICE

Teamwork in Asia

Gear tooth quality check

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The condition monitoring magazin

PreviewIn our June issueyou can read about:

CM application: Automatic overloadmonitoring in a steelworks

Level 1 Basic course: Characteristiccondition values for rolling bearings

Level 2 Basic rules – Part 4: Rollingbearing-specific excitation frequencies

Technology: Digital and software-sup-ported tele service (2)

Application: Measuring of a test facili-ty for the injection timing gear of Tor-nado jet engines

planetary stage and the crack in theplanet pinion. This confirmed the diag-nosis, but cracks cannot be repaired andthe kiln would have to be shut down oneweek later at the very latest. Productionwas at risk. A replacement gear wasrequested.

One day later on Friday evening, atelephone call was received in Herne toreport that no replacement gear couldbe found, and an emergency repairwould have to be carried out. The pro-duction of a new planet pinion beganthat same evening and, Mr. Krollpfeifer,head of the Flender Service hardeningshop, agreed to make space available inthe hardening furnace for the new plan-et pinion on Monday evening. Fig. 4shows a view of the hardening shopwhere, during casehardening in the fur-nace at 940 °C over a period of 16 hours,carbon is diffused into the surface of theteeth so that the hardness required for aplanet pinion of that type is reached. Atthe same time, however, no deforma-tions must occur because the casehard-ening depth that is achieved is only afew millimeters. On Wednesday, i.e. 2days later, the new planet pinion wasfinished by grinding so that it couldoperate together with the other planetpinions and also had the required geartooth quality. The cover photo shows agear tooth measuring machine, which isused to check the gear tooth quality anddocument the final finish.

Express shipping was organized, sothat a service technician delivered thethe pinion on Saturday, i.e. only oneweek after it was ordered, and he saw toit that the roll press could be put intooperation again.

In the meanwhile, the destroyed plan-et pinion was analyzed to discover thecause of the crack. As material and heattreatment errors could be discounted, agear controller with torque measuringtechnology was installed. This operatescontinuously online to monitor vibra-tions and torque in order to identifycritical operating conditions, and then toremedy them selectively. The initial re-sults were sent in an automatically gen-erated eMail that was received by thecopy deadline of this magazine. Theresults will be discussed later in thisissue. ■

Fig. 1: View of the roll press drive duringmobile condition diagnosis

Fig. 2: Initial envelope analyses made itpossible to diagnose the damage

Fig. 3: The crack in the dismantled planetary stage Fig. 4: View of the FlenderService hardening shop

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Roland Schühle, Mathias Luft, Franz Lebitsch

Today, fault diagnosis and trouble-shooting often require external special-ists.

During these assignments, the traveland daily expenses often exceed thecosts for the actual activities on site.

Enormous savings can be achieved inthis situation through the use of teledi-agnosis, as travel expenses no longerhave to be paid if the experts are only onsite virtually. The costs of communica-tion that arise from the use of web-capable or Internet-capable diagnosticsystems are insignificant - even for appli-cations at the other side of the world.

The following examples demonstratetelediagnosis in practice.

Example of a strip mine:1. The control station driver for the

rough cut stage receives an alarm mes-sage from the vibration monitoring sys-tem of drivehead ATS71.

2. He informs the responsible systemengineer. The system engineer accessesthe network to check the stored trendhistory. He actually discovers a trend ofcontinuously increasing vibration val-ues. To uncover the underlying cause, hecontacts the internal specialists of theengineering department at head office50 km away.

3. The specialist engineer at headoffice compares the automatically re-corded alarm spectra with the storedreference spectra over the network anddiscovers several conspicuous damagefrequencies that can be traced to one ofthe two gears. However, as the extent ofthe damage is not yet clear, he requetsadditional advice from a specialist con-sultant service partner.

4. The service partner also logs intothe diagnostic system via telecommuni-cation. The web capability enables thetwo specialists to access the same trendand signal data held in the diagnosticsystem at the same time. They can joint-ly diagnose escalating damage in thefirst stage of the gearing.

5. The operator is then advised toopen the inspection hole cover for thesecond stage on the downtime day of thecoming week and to carry out a visualinspection.

Technology

Digital and software-supported tele service (1)

Example of an energy system1. A machine manufacturer supplies a

turbo compressor to Chile. During thetrial period, the machine condition mustbe monitored. The current conditiondata must be obtained automatically asthe service personnel should not be un-necessarily encumbered with data acqui-sition. The Internet is used as the trans-mission medium because the quality ofthe worldwide connection is very goodand only the costs for a local call areaccrued.

2. The monitoring system is config-ured so that a frequency analysis can becarried out daily and the signals areevaluated on the basis of the currentoperating condition. As long as the oper-ating conditions do not change, no fur-ther actions are carried out except forsending an eMail that contains a briefstatus message. If fluctuations in theload and peak overload occur, the moni-toring system independently carries outmore extensive frequency analyses andsends them by eMail to the service de-partment of the machine manufacturer.

3. The diagnostic specialist of themanufacturer looks through the accu-mulated data and determines that peakloads occur particularly frequently dur-ing the startup procedures.

4. The operator in Chile is supported

by the service department in optimizingthe startup regime.

Prerequisite for this global concept isthe network capability and multiusercapability of the monitoring system andthe availability of a TCP/IP networksuch as, e.g. LAN, WAN or Internet. Inthese networks, so-called routers play acrucial role. They enable authorized us-ers to access the monitoring systemsintegrated in the network and they blockunauthorized data traffic. The so-calledIP address is used for addressing individ-ual participants.

A user can also be connected with aTCP/IP network by telephone modem orby ISDN to access the monitoring sys-tems. The transition to the TCP/IP net-work is made in this case by an accessrouter that checks the user name, thepassword and the telephone or ISDNnumber of the user before it releasesaccess to the network. The firewall func-tion integrated in the router protects thenetwork against unauthorized access.

The Internet can also be part of aTCP/IP network. In this case, so-calledInternet providers control access to theInternet. In the case of an Internet pro-vider, a crossover is made from thetypical national telecommunicationtechnology to Internet technology.

Continued on page 8. �

Service partnerDiagnostics specialist

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ever shorter vibration periods), ever in-creasing energy would be required.Therefore, with increasing frequency,the level of the vibration velocity dropsand the level of the vibration displace-ment drops even more sharply. Conse-quently, as a rule the vibration velocityshould only be evaluated up to 1000 Hzand the vibration displacement should

only be evaluated up to approx. 400 Hz.Monitoring the vibration displacement

gives the best results for low-speed ma-chines. In machines with rolling bear-ings, piezoelectrical acceleration trans-ducers on the bearing case are used forthis. However, the signal must then beintegrated twice.

In machines with sleeve bearings, thevibration of the rotor is evaluated. Forthis reason, noncontact displacementtransducers are technically better here,even though they also represent themore expensive solution. They supply avibration displacement signal directly.This is used to monitor the relative shaftvibration and displacement so thatchanges can be identified earlier com-pared to the measurement of absolutehousing vibration.

Special characteristic vibration valuesthat can be recorded up to very highfrequency ranges (up to 40 kHz andhigher) have been developed for moni-toring rolling bearings. However, moreabout that in the next issue. ■

Level 1Characteristic vibration values (continued)

Condition Monitoring basics

For acceptance measurements and thecondition monitoring of machine sets,broadband characteristic vibration val-ues are mostly used. If the thresholdvalues are exceeded, this leads to awarning, an alarm or even switchoff. Instandard units such as fans, motors, andpumps, a broadband evaluation is madevia a vibration severity measurement in

compliance with DIN-ISO 10816-3. Thisrecommends using the effective value ofthe vibration velocity within the rangeof 10-1000 Hz. Only in low-speed stan-dard machines with an RPM between120 and 600 RPM must the recordedfrequency range be extended down-wards to 2 Hz.

Frequently, other characteristic vibra-tion values must be used for monitoringspecial machines because, e.g. the fre-quency range to be monitored may lieabove 1000 Hz. Sometimes, suitablecharacteristic vibration values can onlybe obtained by using adapted signalfiltering because interferences must besuppressed, or –especially– a weak intel-ligence signal must be amplified.

In turbo gears, the effective value ofthe vibration acceleration is monitoredin order to evaluate the meshing. Thevibration acceleration does not showany drop in frequency response in thehigher frequency range unlike the vibra-tion velocity.

For a machine component to vibrateback and forth at higher frequencies (or

Glossary oftechnical termsDid you know?

Router:Routers are coupling elements that con-nect the various networks (LAN, WAN,Internet) with one another. They ensurethat data packages are forwarded to theother networks as long as the recipient isnot present in the same network. Therecipients are recognized by their IPaddresses. There are also routers that areindependent and that can establish a con-nection to another network by telephonemodem or by ISDN if required. The connec-tion is only continued for as long as it isactually required.

Firewall:A firewall is a safety mechanism, whichprotects a closed network (Intranet)against unauthorized use. This is achievedby a combination of encryption, passwordsand access authorizations. Essentially, afirewall decides whether access is allowedor rejected on the basis of the informationcontained in a data package.

Intranet:Intranet describes a company-internal net-work that uses the technologies of theInternet. Among other things, this includesthe display of documents using HTML,displaying them using a browser, and pro-viding access to the Internet server andeMail. It is based on TCP/IP.

LAN:LAN is a closed local network that is limitedto a restricted local area and does not useany public lines (telephone, ISDN). Therange can cover a company site, for ex-ample. It is based on TCP/IP and the dataare accessed by means of Internet techno-logy.A LAN or parts of a LAN can also berealized by radio. This technology is calledWLAN. The frequencies used for this donot require a licence and are not liable tocosts.

WAN:WAN is a remote area network that usespublic or internal company trunk lines andcan cross national and/or continental bor-ders. It is based on TCP/IP and the data areaccessed by means of Internet technology.IP addressThe IP address is a string of 4 groups ofnumbers (e.g. 198.168.1.131) that is requi-red for the unique identification of a TCP/IP communication participant in a specificnetwork.

Dieter Franke

Displacement

Vibration velocity

Vibration acceleration

Shockpulse

measurement

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Part 3:Calculating machine-specificexcitation frequencies

Especially in high performance ma-chines and gears, it has been shown thatthe consistent application of frequencyanalyses considerably increases diagnos-tic certainty. However, what is the pointof the best frequency analyses if theexcitation and damage frequencies arenot known? We recommend calculatingall typical excitation frequencies and asmany interfering and damage frequen-cies as possible before every measure-ment whenever possible.

In today’s Level 2, we begin with thecalculation of machine-specific excita-tion frequencies that occur to a greateror lesser degree in every rotating com-ponent using the example of a simplefan drive. The diagram shows a drive ofthis type consisting of an asynchronousmotor, a single-stage spur-wheel gearand a fan.

Using the characteristic mechanicaldata of machines, it is possible to calcu-late any rotational synchronous excita-tion frequencies that occur. Further-more, nonrotational synchronous vibra-tions may also occur that can be tracedback to the intrinsicfrequencies of com-ponents of the ma-chine set.

Machine vibra-tions also occur un-der good conditionswhere, as a rule, theamplitude height isdecisive in evaluat-ing the condition.

The following typ-ical excitation fre-quencies can arise inthe sample aggre-gate shown in thediagram:

Level 2Basic rules for the measurement of frequency spectra

Condition Monitoring basics

A) Fundamental frequenciesThe main excitation in all rotating

machine sets is the residual unbalance atthe rotors that cause fundamental fre-quency vibrations.

The fundamental frequencies in Hzare calculated from the machine rota-tional speed in RPM divided by 60. Thegear ratio can be used to check whetherthe specified nominal speed of the motorand pump agree. Often higher harmon-ics (integer multiples) and, in specialcases, even subharmonics (integer divid-ed multiples) and interharmonics (0.5-fold, 1.5-fold, ...) can also be monitored.

Loaded asynchronous motors showhigher slip than unloaded motors. Thenumber of revolutions decrease and,consequently, so do the fundamentalfrequencies. As a result, frequency ana-lyzers can be used to estimate loadconditions.

B) Blade passing frequenciesThe blade passing frequency can be

calculated as the product of the rotatingfrequency and the number of blades. Itmust be noted that, particulary in venti-lators, fans and pumps, several multiplesof the blade passing frequency can also

occur. This effect is particularly typicalof axial ventilators, where each impellerblade runs past an imperfection andexperiences an impulse excitation due toa short fluctuation in pressure.

C) Gear mesh frequenciesThe occurrence of the gear mesh fre-

quency is typical for gears. It arises fromthe impulse excitation in the meshing ofeach individual pair of teeth. The gearmesh frequency can also be calculatedby multiplying the number of teeth onthe pinion wheel and/or on the gearwheel with the respective rotational fre-quency. In the case of simple gears, if thenumber of teeth is not known, it can becalculated from the frequency spectra oreven counted on the open gear. In thecase of multistage gears, the manufac-turer of the gear should be contacted,who can then give the number of teethfrom archived documentation of thegear using the production number onthe identification plate. Also, in toothedwheel gears, it must be noted that theoccurrence of harmonics of the gearmesh frequency is not a deficiency of thegear. ■

Ventilator Gearing Motor

Number of revolutions:n

2 = 3738 RPM

Fundamental frequency:f

n2 = 62.30 Hz

Number of blades= 17Blade pass frequency:fBPF = 17 x fn2 = 1059 Hz

Rolling bearing type 22212Bearing failure frequencies:

Inner ring: fRPIF

= 615.2 HzOuter ring: f

RPOF = 443.9 Hz

Rolling elem.: fRPF

= 370.5 HzBearing cage: f

CRF = 26.11 Hz

z1 = 73 teethz2 = 29 teethGear mesh frequency:

fZ = fn1 x z1

= fn2 x z2

= 1807 Hz

Number of bars= 58Bar frequency:

fRB = 58 x fn1 = 1436 Hz

Number of revolutions: n1 = 1485 RPM

Rotating frequency: fn1

= 24.75 Hz

1 2 3 5 10 20 30 50 100 200 500 1000 3000 10000 flog in Hz

v inmm/s

a inm/s²

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Massive problems had been experi-enced during start up of a propanerefrigeration compressor. On several oc-casions, the unit had to be shut downafter less than an hour in operation dueto extreme heating of the motor-shaftbearing arrangement.

The cause for the high rise in tempera-ture within the bearing arrangementremained a mystery. The motor shaftand the compressor shaft had previouslybeen aligned cold using ROTALIGN®

PRO to 0.04 mm offset and 0.04 mm gapat 300 mm coupling diameter. With theunit operating at 2990 rpm, the values

were within permissible rangeof alignment. Further align-ment of the unit would notimprove its running condition,and takes time.

‘Thermal’ movement had notbeen considered an influence asthe supplier of the machineryhad suggested that this move-ment was negligible.

To get to the root of the prob-lem an elimination process wasselected.

The compressor supplier de-cided to check for machinerymovement due to the tempera-ture changes while in normaloperating conditions.

The PERMALIGN® system isthe ideal laser alignment equip-ment for ‘thermal’ movementmeasurements and has proved

itself over many years.In this instance, a vertical and a hori-

zontal PERMALIGN® monitor weremounted at suitable locations of thecasing of the sleeve bearing high-voltagemotor. The transmitted laser beam isreflected back to the monitor by a roofprism mounted opposite and reaches thethe effective position detector of thePERMALIGN® monitor, which has a highresolution and is stable over time. Theroof prism principle allows the measure-ment of two degrees of freedom usingone monitor, e.g. in this case, a paralleloffset and an angularity in two axes. Thefour shaft alignment parameters arethen monitored simultaneously by a ver-tical and horizontal PERMALIGN® moni-tors, i.e. - parallel offset and angularity,both horizontal and vertical.

A Windows software for PERMALIGN®

automatically stores all collected dataand calculates the actual shaft align-ment from the raw data. This enableschanges in position to be traced overhours, days, weeks or even years.

This measurement construction en-abled the 4 four alignment parameters• vertical offset• vertical angularity• horizontal offset• horizontal angularity

to be recorded in their relative changebetween the compressor and motor. Theparallel offset is the centerline offset ofthe motor shaft and the compressorshaft to one another in the middle of thecoupling planes (i.e. in the middle be-tween the two coupling flanges), mea-sured in millimeters.

The angular offset is the angular errorbetween the two shaft axes, respectiveto the coupling diameter of 300 mm, asa gap measured in millimeters.

Parallel to this, the temperature of themotor and compressor casing was mea-sured at 23 locations spread evenly be-tween the driver and the driven machineat short intervals.

Immediately after the compressorstarted running, a horizontal offset posi-tion was detected, i.e. the compressorhad moved towards the right (lookingfrom motor towards compressor). After5 seconds the offset was –0.02 mm, thevalue increasing to –0.05 mm after 35seconds. A maximum value of –0.10 mmwas attained after 7 minutes. After at-taining this maximum value, the com-pressor gradually moved back to thecentre position.

It was also observed that the move-ments after start up remainedsmaller when the compressor hadpreviously run as opposed towhen the compressor had beenstarted from cold.

It appeared that the compressorcasing heated unevenly. The leftside heated quicker than the rightside. It was for this reason that thecompressor moved towards theright after it started to run. Theentire compressor casing attaineda uniform temperature after about

Mathias Luft (PRÜFTECHNIK VD)

Measuring the ‘thermal’ movementof a propane refrigeration compressor

Application

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30 minutes, and therefore the reasonwhy the compressor returned to thecentre position after about 30 minutes.

The parallel tendency of the horizon-tal angularity is inevitable. A maximumhorizontal gap of –0.07 mm at 300 mmcoupling diameter was attained afterabout 7 minutes.

The vertical offset increased as thecompressor warmed up. The drop invalue at point 8 (19:57 hours) couldmost likely have been as a result of thethermal movement of the motor. Thefinal temperature of the motor casingwas reached between 20.00 and 20.30,and this could have compensated thethermal movement of the compressor.

Final alignment parameters at 20:30Verticaloffset: +0.227 mmangularity: +0.058 mm / 300 mmHorizontaloffset: +0.019 mmangularity: -0.010 mm / 300 mmJust before shutdown, the compressor

was + 0.227 mm higher than the motor,the gap opened upwards 0.058 mm at300 mm coupling diameter.

Horizontal offset and angularity couldbe neglected. However, forces arise inthe vertical axis that are too large withreference to 2990 RPM.

Considering the casing temperatureson the compressor and motor, thechange of the shaft alignment due tothermal movement is plausible. Figure 3shows the temperature trend based onthe measurements recorded at the 23temperature locations.

The position where the monitors aremounted while measuring thermalmovement is of importance. In the above

example, the centerline ofthe compressor was 530mm, while the monitor wasmounted such that the laserbeam axis was at 280 mmabove the centerline - de-pendent on the constructionof the sensor attachments.This reduced the effective‘thermal’ movement to 65%of the measured values. Theeffective final alignment pa-rameters as recorded at20.30 would therefore be:Vertical offset:+ 0.15 mm(compressor high)Vertical angularity:+ 0.04 mm / 300 mm(gap opens upwards)

SummaryDespite careful ‘cold’

alignment to within 0.01mm, the shaft alignment ofthe unit deteriorated sharp-ly under normal operatingconditions, and was steeplyout of tolerance by a factorof five.

The following cold alignment targetswere recommended to the machinemanufacturer for changing the align-ment instructions to compensate for thethermal movement to the following val-ues:

Vertical offset:- 0.15 mm(compressor lower)Vertical angularity:- 0.04 mm / 300 mm(gap opens downwards). ■

Legend of figures:

Fig. 1Propane refrigeration compressor· Propeller compressor construction· Sleeve bearing high-voltage motor· Rating: 660 kW· Rotational speed: 2990 RPM

Fig. 2PERMALIGN® system· Horizontal and vertical monitor· Each with roof prism mounted opposite

Fig. 3Temperature trend

Fig. 4PERMALIGN® PC software

1 17:23 Monitoring started2 17:25 1st. run Compressor started3 17:25 Compressor turns off

after approx. 10 s4 17:33 2nd. run Compressor restarted5 17:40 Compressor turns off6 18:23 3rd. run Compressor restarted7 19:37 Compressor turns off8 19:57 4th. run Compressor restarted9 20:30 Compressor switched off

vertical offset

vertical angularity

horizontal angularity

horizontal offset

Alignment under ‘cold’ conditions

Alignment after 7 minutes

Alignment after 3 hours (final condition)

Machine temperature trend

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Imprint

PRÜFTECHNIK AGPostfach 12 6385730 Ismaning, Germanywww.pruftechnik.comPhone: +49 (0)89-99616-0Fax: +49 (0)89-99616-200eMail: [email protected]

Flender Service GmbHCondition MonitoringSüdstrasse 11144623 Herne, Germanywww.flender-cm.comPhone: +49 (0)2323-940-220Fax: +49 (0)2323-940-229e-Mail: [email protected]

News

NewsGearController® & VIBRONET®

Ex-version now in operation

A few weeks ago a GearController®

was put into service on the currentlylargest single shaft extruder of theworld, where a new type of Ex protec-tion concept was realized for the firsttime. A total of 24 intrinsically safeaccelerometers and six Ex-protectedmultiplexers of the protection type EExib IIC T4 were used in the intrinsicallysafe zone. The measured signals arebrought to the GearController via aspecial cable and a special protectionthat is located outside the protectedzone. In the customary manner, the mea-surement routines run automaticallyand the gear and –especially– rollingbearing conditions are monitored. Sig-nals are supplied to the customer via aCAN bus. For the first production-criticalyear, the specialists of Flender ServiceCondition Monitoring were immediatelyinstructed to monitor the running andoperational behavior of this driving so-lution. The measured signals from Ma-laysia arrive automatically in Germanyby eMail. ■

VIBSCANNERwins the prize once again

VIBSCANNER was voted as product ofthe year 2001 by the readers of the PlantEngineering magazine and was honoredwith a gold medal.

The “Best product of the year” prize isawarded by the international Plant Engi-neering magazine to the most innovativeproduct that provides the greatest bene-fits in the industrial plant technologysector. The presentation ceremony willbe held at the this year’s Plant Engineer-ing and Management Show in Chicago,Illinois.

� Continued from page 3:Software-supported

tele serviceA special router or Internet access

module is available for direct access tothe Internet by a monitoring system. Themonitoring system can log itself into theInternet independently by telephonemodem or by ISDN and send eMails viathis route. ■

Find out about the different possibilitiesfor continuous monitoring in our newVIBRONET® Signalmaster brochure anddiscover how you can be informed bySMS if a machine fault occurs. ■

EventsVisit us at international trade fairs and exhibitions:

Flender ServiceCurrent dates are given on our Internethomepage.

PRÜFTECHNIK AGHannover trade fair15.4. - 20.4.2002Hall 8 - Stand A21

Further current dates are given on ourInternet homepage.

You can request a printed copy of ourshort ‘Alignment made easy’ guide-book free-of-charge by telephone oreMail. ■

Documents

Telediagnose g 03 (Refrigeration Compresor)