1

Torque is the most important condition monitoring measurement parameter for detecting dangerous torsion-al vibrations that can overload the diesel motor, the coupling and / or the generator. In addition to calculated torsional vibrations, torque measure-ments with strain gauges are a very direct and practical method for detect-ing torsional vibrations.

But what if spatial conditions prevent the application of a strain gauge or if the drive system cannot be retrofitted with measuring flanges? It would be possible to shorten the coupling flange or make ‘windows’ in the coupling flange and apply the strain gauge there. But it is difficult to implement this on an existing ship generator and impossible with large machines.

A Greek shipowner was supposed to have such a modification on a ship generator accepted by a classification society. But he wanted to find an al-ternative method of providing the re-quired torsional vibration proof and contacted PRÜFTECHNIK with a request for support.

“Angular deflection analyses provide alternative torsional vibration proof in such drive linkages,” was our recom-mendation. For this purpose, the angular pulse sequences are measured on both

sides of the highly flexible coupling at high resolution and then mathematically processed. It was fortunate in the case of the application shown in Fig. 1 that a highly flexible VULKAN coupling was used. This coupling has the advantage that the same number of impulse marks are provided at the factory on both cou-pling ends, evenly distributed on the cir-cumference, both primary and secondary.

In the event of dangerous vibration con-ditions in the generator, the diesel motor or the highly flexible coupling, danger-ous torsional vibrations can quickly be determined based on the angular deflec-tion on the input and output side and the differential angular deflection.

Several recorded impulse sequence curves are shown in Fig. 4: measurement of the diesel motor side on the left –

Fig. 1: The on-board generator, driven by an MTU diesel motor

Condition Monitoring Service

Acceptance test of torsional vibration in the generator Dr. Edwin Becker, Ismaning

… and prosperity and since 2010 a combined heat and power plant (CHP) and its generator supplement the power and heat supply at PRÜFTECHNIK.

Generators are used in nearly every autonomous industrial application and provide an uninterrupted power supply at a stable voltage level. The number of autonomous generators is impressively on the rise – mostly due to wind turbines. When so-called micro-CHPs provide for

autonomous power supply in the private sector in the future, generators will be-come a subject of interest for many peo-ple. All generators have one design prin-ciple in common: low vibrations and / or good installation are synonymous with low wear and a long service life.

This issue is devoted in particular to generator systems running with constant speed and discusses the different influ-ences on their vibration behavior.

PRÜFTECHNIK News

Generators provide power …

No. 14 – Subject: Generators

In this issue:

Acceptance test of torsional vibration in the on-board generatorNatural frequencies in the hydro-electric generatorAcceptance criteria and permissible vibrations in generatorsDisturbing vibrations in the ship generatorFMEA-based condition monitoring in traction generatorsGenerator operates only with partial load – why?Documentation of vibration compe-tence with ISO certificate Alignment errors on generator of an express ferryBalancing of generators40 years of PRÜFTECHNIK

2

measurement of the generator side on the right.

These time waveforms of the angular pulse sequences can be used to first analyze the machine-related frequencies and then the corresponding angular de-flection deviations (Fig. 5). The impulse frequencies are not relevant in these frequency spectrums, but only the over-laid excitations specific to the on-board equipment.

The desired information on the rela-tive angular deflection can be derived with the help of mathematics. Several of the relevant results for the accep-tance inspection are shown in Fig. 6 for 1800 rpm for a 10 % and 80 % generator load. It was possible to calculate cor-rect vibration behavior and acceptable angular deflection of a maximum of 1.5 degrees.

All results were summarized in a mea-surement report as commissioned, so that the responsible classification society was able to determine whether the tech-nical modification is permissible. After some coordination and explanations on the measuring procedure, the modifica-tion was approved.

It should be mentioned here that the patent-pending algorithm is also used in the PRÜFTECHNIK online condition monitoring systems.

Fig. 2: Stroboscopic ‘static’ angular deflection analysis

Fig. 4: Time curves of the angular momentum sequence measured with an analog method on both sides of the VULKAN coupling

Fig. 5: Frequency analyses of the measured angular momentum sequences. Generator on left – motor on right.

Fig. 6: Angular deflection trends calculated from the angular momentum sequences at 1800 rpm rated speed, at 10 % load and at 80 % load.

Fig 3: Layout of the sensors temporarily mounted on the coupling

PreviewIn the next issue you can read all about hydroelectric power plants

– Disturbing noises in a hydroelectric power plant

– Field balancing in run-of-river power plants

– Impact tests on turbine wheels

– Online measuring technology and remote monitoring of hydroelectric power plants

3

Drive technology is becoming increas-ingly compact. The following example from a hydroelectric application shows that rotor-dynamic influences can play a role in simple generator systems: The impeller of a Francis turbine, which was flanged directly onto the generator rotor, displayed excessive vibration values. The increased vibrations were noticeable soon after the generator was put into operation. It was necessary to conduct an extensive measurement analysis of the vibration behavior, since it was suspected that reinforcement elements installed by the manufacturer were causing natural vibration excitations.

Condition Monitoring Service

Natural frequencies in the hydroelectric generatorDr. Alvaro Chavez, Ismaning

Figures 1 and 2 show the Francis tur-bine, the impeller on the generator rotor, the mounted displacement sensors and accelerometers and the trigger sensor. The frequency spectrums of the hous-ing vibrations and the shaft vibrations are shown in the two diagrams. The measurements of the vibration velocity and the shaft vibration show irregularly high and broadband vibrations at about 44 Hz. The rotational excitations remain low.

What is the cause of this? Further systematic measurement analyses deter-mined that a force-excited natural vibra-tion was responsible. It was possible to shift this broadband natural frequency

at 44 Hz somewhat by means of tempo-rary reinforcements and it disappeared immediately upon removal of the load. These results led to the conclusion that a bending natural frequency was being excited by the bearing concept used in the generator.

With bending vibration calculations it was possible for the generator manu-facturer to reproduce the results of the measurement and to simulate different solutions for reducing the vibrations, under special consideration of the bear-ing elasticity. It was necessary to change the bearing concept.

Fig. 1: The hydroelectric plant and the generator rotor with flanged-on impeller. The installed displacement sensors, the accelerometer and the laser trigger sensor can be seen.

Fig. 2: Frequency spectrum of the vibration velocity – measured at the generator housing.

Fig. 3: Frequency spectrum of the relative shaft vibrations – measured directly at the rotating shaft.

1. Rotational frequency

2. Harmonic 3. Harmonic

Resonant excitations (with ‘hull’)

4

Rated speed of the re-

ciprocating combustion

engine

1-cylinder motor

Value 1 Value 2

but

Rated output of the generator system

Vibration amplitude

Reciprocat-ing internal combustion engine 2) 3)

Vibration velocity Vibration acceleration 1)

1-cylinder motor

Reciprocat-ing internal combustion engine 2) 3)

Reciprocat-ing internal combustion engine 2) 3)Value 1 Value 2

Value 1 Value 2

but

but

but

but

but

but

but

but

but

but

Condition Monitoring Principles

Acceptance criteria and permissible vibrations in generators in different applicationsDr. Edwin Becker, Ismaning

Once a suitable generator has been selected, the running, vibration and op-erating behavior should be checked after startup. But which measurement loca-tions and which acceptance criteria are to be used for generators?

The answer to this question has to be: There is no standard answer.

Permissible vibrations in large power generators

ISO 8528-9 allows surprisingly high vibration amplitudes for generators in large power generation units and pro-vides recommendations for suitable mea-surement locations. Figure 1 shows mea-surement locations on a generator unit. In the adjacent photo the measurement locations on the generator of a larger gas motor combined heat and power plant are marked. A special feature of ISO 8528-9 is that both RMS and 0-P vibration values are quantified based on power and speed. Also, the high second-ary vibrations affecting the generator and especially the roller bearings are taken into account.Permissible vibrations in generators

in submarines and yachtsGenerators in submarines and / or in

yachts on the other hand have to operate with significantly lower vibration val-ues – often so low that the manufacturer and customer agree on individual mea-surement locations and spectral vibration values. PRÜFTECHNIK has integrated functions in VIBXPERT® to visualize

Fig. 1: Typical measurement locations in power generation units (left from ISO 8528-9, right from acceptance measurements by PRÜFTECHNIK Service)

Fig. 2: Informative vibration limits for power generation units (from ISO 8528-9)

Fig. 3: Depiction of the VIBXPERT results as structure-borne velocity level (third-octave level in dB re 5 x 10-8 m/s).

5

v (mm/s) a (m/s²)

µm

Condition Monitoring Principles

Acceptance criteria and permissible vibrations in generators in different applicationsDr. Edwin Becker, Ismaning

Fig. 6: Overall vibration values of generators on wind turbine (left velocity, right acceleration)

the curves for the permissible structure-borne velocity level with an arbitrary reference value. Figure 3 shows such a diagram – which however was measured with a calibrator for reasons of confidentiality.

Permissible vibrations of generators in general

If there are no individual vibration threshold values, the vibration behavior is to be eval-uated according to IEC 34-14 or ISO 10816-3 (see Fig. 4).

Permissible shaft vibrations in large generators larger than 50 MW.

In Telediagnose No. 13 we discussed threshold values for shaft vibrations in turbo sets of large power plants. These vibration thresholds are also to be used for large generators. Figure 5 differ-entiates between vibration thresholds for 50 Hz and for generators in 60 Hz voltage networks.

Current developmentsIn the national and international stan-

dards systems, new application- related standards are created on a regular basis and vibration thresholds are revised accordingly. This also applies to genera-tors. PRÜFTECHNIK actively contributes to several VDI, DIN- and ISO task forces.

An example for such a new standard for generators on wind turbines: VDI 3834 describes the permissible vibra-tion thresholds for generators on wind turbines both as assessment velocity and as assessment acceleration (Fig. 6). It is noteworthy that this directive specifies different frequency ranges and that in addition to the vibration velocity also the acceleration is used for evaluation. Currently, conversion of VDI 3834 to ISO 10816-21 is in progress.

Glossary of termsDid you know?

Electric rotor asymmetries occur as a result of breaks in rotor cage rods, usually near the coil ends or due to production defects.

A shorted coil is indicated by electrical im-pulses that occur both between the stator terminals and between the star points and the earth.

Eccentricities usually occur as a result of shaft deformation or inexact centering of the shaft in the bearing.

Static eccentricities mean that the smallest distance between the impeller and the stator remains at the same location in the stator due to an elliptical rotary field.

In the case of dynamic eccentricity the smallest distance between the stator and rotor rotates in circumferential direction. This can affect the magnetic attraction force, distort the rotor and increase eccentricity.

Polarity – the number of poles results in different rated speeds. A 2-pole generator rotates at 3000 rpm, a 36-pole generator rotates at 20 rpm (in relation to 50 Hz). This results in the pole passing frequency. It can be specified, but not the sidebands.

Slot frequency – If the number of slots is optimal, the number of critical harmonics is minimized and noises / vibrations are reduced. The rotor slot frequency is calculated from the number of rotor slots x rotational frequency and the stator slot frequency is calculated from the number of slots in the stator x rota-tional frequency.

Slip frequency: Synchronous generators operate directly online. Asynchronous gen-erators operate in supersynchronous mode and are subject to slippage. Therefore, the slippage and also the slip frequency can be derived from the difference in speed.

Alternating torques are caused for example by winding fields and by asymmetries in the stator and shaft. In the case of stator asym-metry, an alternating torque occurs with double line frequency; in the case of shaft asymmetry, the alternating torque occurs with double slip frequency.

Reactive power occurs due to reactance, causing a phase shift in AC circuits. All types of inductors and capacitors produce the effect of reactance. Due to the nearness of the conductors in very long cables, they also act as capacitors and can result in electro-mechanical secondary vibrations.

Harmonics play a role only in generators with a converter. The self-commutated im-pulse converters normally used today with a clock frequency in the kHz range have low harmonic levels.

Fig. 5: Shaft vibration parameters of large turbo generators – left for 50 Hz, right for 60 Hz line frequency.

Fig. 4: The RMS value of the vibration velocity as evaluation criterion for the machine condition

6

Vibration severity prior to blocking of the bear-ings at constant speed

Machine stop at see, visual

inspection of the generator

Maximum vibration after blocking of the

bearing 82 rpm “50 % Load” double rotational frequency = wobble/displacement of the shaft (v = 78 mm/s)

82 rpm “No load” rotational frequency = imbalance

ISO alarm threshold

Vibration severity after blocking of the bearings

at variable speed

Condition Monitoring Experience

Disturbing vibrations in the ship generatorFlorian Buder, Montreal

A shipowner reported increased vibrations on a freighter to the gen-erator manufacturer. PRÜFTECHNIK was contracted by the electrical machinery supplier as an independent diagnostic service provider to search for the causes during passage from Italy to Gibraltar.

Before the ship left the port of Ca-gliari the alignment between the gearbox and the generator was checked with the laseroptical alignment system OPTALIGN® smart. It turned out that the misalignment values were within tolerance; nevertheless, the unit was realigned. Afterwards, the Condition

Monitoring System (CMS) VIBNODE® was installed as a data logger in order to constantly monitor the operating and vibration behavior upon departure of the ship. The results from the frequency analyses were astonishing. As the gen-erator load increased, excitations oc-curred in the double rotational frequency spectrum with vibration velocities of up to 50 mm/s, which is absolutely imper-missible. Since proper alignment had already been carried out in the harbor, an alignment error was ruled out im-mediately. The crew was advised to disconnect the generator and to seek the

cause in the generator itself. They found a loose bearing outer race on the B side. It was tightened, with the result that the vibrations decreased (see Fig. 2). But now the vibrations in the single rota-tional frequency spectrum dominated. And the envelope spectrums also showed very distinct rotational excitations, which indicated a cracked bearing, excessive bearing play or a worn out bearing seat. It was necessary to replace the generator, which was requested while the ship was still at sea, in order to make the neces-sary preparations in the next port.

In addition, the bearing cap was re-moved at the next op-portunity and a worn out bearing seat was found.

Fig. 1: Views of measurement task on the freighter

Fig. 2: Results of the VIBNODE® CMS in data logger operation and comparison of the frequency spectrums without load and with generator load

7

Vibration-based condition monitor-ing is very user-friendly with modern measurement hardware and database-powered analysis software. In general, there are two types: offline and online condition monitoring. Both methods are signal-based and allow recording and diagnosis of generator conditions for sub-sequent monitoring of tendencies.

First, of course, the priority of the generators must be decided based on availability-oriented maintenance, in order to select the correct procedure and the suitable condition monitoring tools. Priority A generators should be equipped with online condition monitoring sys-tems. For priority B and C generators it is sufficient to use regular offline condition monitoring.

The results of FMEA* or FMECA** analyses should be taken into account – especially in the event of errors or failures in the generators themselves. So-called single-bearing generators and genera-tor sets with different base frames have a higher potential for damage than gen-erators with a compact design. The type of bearings in the generator itself and the coupling types used can also result in premature failure. The risk figure can be reduced with higher precision dur-ing balancing and alignment. With both methods, knowledge of the condition monitoring process is useful, as shown by the following example for a drive sys-tem in a long-distance passenger train.

Condition Monitoring Technology

FMEA-based condition monitoring in traction generatorsJohann Lösl, Ismaning

The first step is to create an Ishikawa diagram for description of the machine structure. This is followed by the fault tree analysis, as shown in the table on page 8. Critical components are identi-fied by means of the risk figure, based on the following formula:

Risk priority number =occurrence / probability A x significance / severity of damage B x discovery / detectability E

For risk numbers below 125, no mea-sures are necessary – from 125 to 250 there is an increased residual risk and ad-ditional maintenance measures are nec-essary. Risk numbers above 250 indicate an unacceptable residual risk, requiring engineering modifications.

The following example shows how FMEA can be used for generators in a railway application to identify and eval-uate causes of damage to the generator. In this example it is also possible to quan-tify a 40 % risk reduction by introduc-ing vibration-based condition monitoring (see following page).

PRÜFTECHNIK uses such FMEA-based analysis methods not only in the Service & Diagnostic Center, but has also inte-grated the analysis tools in the analysis software OMNITREND® and VIBGUARD® Viewer.

Evaluation criteria for FMEA

Occurrence / probability AThis analyzes the frequency with which

errors can occur in the component / assembly and how high the risk is that the error will occur in the analyzed object. The values have the following meanings: 1 not likely to occur

2 – 3 occurs very rarely

4 – 6 occurs rarely

7 – 8 occurs frequently

9 – 10 can occur very frequently

Significance / severity of damage BThis analysis determines the effects

and the influences on other components and the entire system. The values have the following meanings: 1 very small error

no effect on the system

2 – 3 small error slight effect on the system

4 – 6 medium error medium effect on the system

7 – 8 serious error large effect on the system

9 – 10 very serious error very large effect on the system

Discovery / detectability EThis analysis indicates the detectability

of the error and at which point in time the error is discovered. Modern condition monitoring methods make it possible to improve detectability. The values have the following meanings: 1 very easily detectable

2 – 3 easily detectable

4 – 6 detectable

7 – 8 poorly detectable

9 – 10 hardly detectable

* FMEA: Failure Mode and Effects Analysis

** FMECA: Failure Mode and Effects and Criticality Analysis

Fig. 1: View of generator drive with sensors mounted in the terminal box.

8

Grounding system

Consumer

Display panel

Cables

Measuring and control technology

Sensors

Power converter

Rails

Lubrication

Clamping rings

Axle shaft

Car wheels

Roller bearings

Car body

Ring gear

Pinion shaft

Hollow shaft

Gearbox housing

Flexible gear support

Roller bearings

Lubrication

Flexible coupling

Sliding sleeve

Universal joints

Cardan shaft tube

Generator housing

Rotor

Lubrication

Stator with winding

Fan

Roller bearings

Power supply

Controller Chassis

Car

Gearbox Coupling Generator

Generator drive

Cause / effect diagram (Ishikawa diagram) for a traction generator

Fig. 3: Fault tree analysis for the ‘generator branch’ of the Ishikawa diagram.

Risk number = occurrence x significance x detectability

Fig. 2: Ishikawa diagram of the traction generator in the passenger train car shown in the photo.

Risk numbers greater than 125 mean increased

residual risk

Risk numbers greater than 250

mean unacceptable residual risk

Possible errors determined through

brainstorming

Corresponds to a 40 %

risk reduction with CM

Reduced risk figures ‘with’ CM

High risk figures

‘ without’ CM

“Generator” fault tree analysis

9Fig. 2: Rotational vibrations, measured in the generator during operation with constant partial load, however with different idle power

Fig. 1: B-bearing of the generator (top) and time curve of the rotational vibrations for diverse load runs with deactivated vibration shut-off (right).

A turbo set in a chemical factory could not be brought up to the rated load as a result of excessive vibrations. In the past, it was used for many years with no problems. Visual inspections of the synchronous generator, the planetary gear set and the turbine showed no signs of damage. PRÜFTECHNIK was contacted to find the cause in an on-site measurement task.

The customer mentioned that other vibration specialists had already mea-sured vibrations in the turbine system. In such cases, we at PRÜFTECHNIK choose other methods for problem analysis.

Condition Monitoring Application

Generator operates only with partial load – why?Marcel Kenzler, Ismaning

In the same conversation it was sug-gested to install online measurement hardware on a rental price basis for tem-porary telediagnosis service (TTS). This is used to simultaneously measure differ-ent frequency-specific characteristic band values at characteristic measurement locations in order to monitor the vibra-tion behavior of the turbo set in different operating states. The order then came two days later. The measurement hard-ware was installed at the site a few days later so that the measurements could be automatically sent to the specialists in the monitoring center. The first results already showed “life” in the rotational amplitudes at 50 Hz, and that imper-missible vibrations existed both in the generator and in the gearbox. The layout of the accelerometers on the B side of the generator and results from the horizon-tal measurement location are shown in Figure 1. It shows the vibration velocities for the load test runs, in which automatic shut-off was deactivated. From these time curves of the vibration velocity it was easy to determine how the excessive increases in vibrations came about after

adding the load. Furthermore, the differ-ent gearbox and generator measurement locations detected strongly directional vibrations, which are not shown here. With this vibration pattern, the suspected gearbox damage was ruled out. After these tests it was therefore decided to operate the generator set only at partial load and to leave the installed TTS on the generator set in order to search for other irregularities.

After only a few days there were signif-icant differences in the rotational vibra-tions, despite operation with a constant partial load throughout the day. There are time periods in which the vibrations were at a high level, and then – usually at night – conditions in which the vibrations were constantly at a low level.

Was the generator in fact operated at a higher load?

The control station was contacted. No, the generator load was constant. In the subsequent parameter analysis it was determined, however, that the vibra-tions always decreased during operation with more reactive power. Keeping the reactive power at a constant low level reduced the vibrations. Very unusual, yet an important indicator to definitely rule out the planetary gear set as the cause of the load-dependent 50 Hz disturbing vibrations. And it led to the conclusion that there was an electrical problem in the generator. A specialized company was contacted to conduct a thorough inspection of the generator in order to search for irregularities. A rather well-hidden defect was identified and cor-rected. Afterwards, the generator system could again be operated at full load with no problems.

10

Condition monitoring systems need professional support. More and better training are the decisive factors for the future of condition monitoring personnel. This necessity was already recognized in 2003 by Germanische Lloyd (GL) for the wind industry and the procedure for certification of the monitoring center was introduced in the form of directives for condition monitoring systems. Through its accreditation in accordance with DIN/EN ISO/IEC 17024, GL then also had the opportunity to conduct independent third-party1 certifications.

Anyone who wishes to become certified as a vibration expert should do so through third-party certification associations.

Why certification?In the machine service sector it has

recently become obvious that customers prefer service providers with certified personnel.

A circumstance that has long been standard practice in industrial nonde-structive testing (NDT). In NDT, only personnel are approved who can conduct an acoustic emissions test, eddy current test, leak test, magnetic particle test, penetrant test, radiographic test, ultra-sonic test and visual inspection and who work in accordance with regulations, are tested regularly and can operate the required measuring devices.

The classification society DNV (Det Norse Veritas) required last year that vibration measurements can no longer be conducted in the offshore in-dustry without ISO-CAT certification and that the personnel have to be identified by their ID numbers. The proof of third-party certification is increasingly being required also at the international level by refineries and major power generation plants.

Condition Monitoring Training

Documentation of vibration competence with ISO certificateSascha Hein, Ismaning

Emphasis on practiceThe purpose of the one-week seminars

is not only to provide extensive informa-tion. The focus is always on practice, in order to ensure that the participants will actually be able to apply what they have learned later in the field.

The interactive PC animations and simulations have proven very effective for learning.

Seminar content, dates and other information can be found in the flyer shown here and on the PRÜFTECHNIK website.

ISO 18436-2The ISO 18436 standard series pro-

vides clear information on certification of personnel in condition monitoring; it should be mentioned, however, that some parts of ISO 18436 are still being written or revised.

ISO 18436-2 is relevant with respect to certification of vibration experts. The standard defines the professional quali-fications that are necessary, the training content to be provided and how the tests are to be conducted. After being adopted, this standard will also be published in Germany as a DIN ISO standard.

Seminars in 3 stagesFor several years now, PRÜFTECHNIK,

in cooperation with the MOBIUS Institute, has offered certified vibration seminars in three categories:

• Cat. I ‘for vibration technicians’• Cat. II ‘for vibration analysts’• Cat. III ‘for vibration specialists’PRÜFTECHNIK vibration semi-

nars comply with the standards of the MOBIUS Institute, which is officially accredited by JAS-ANZ – with standard-ized seminar content and testing require-ments. Officially accredited in this case means worldwide recognition.

The certification can be submitted to employers, colleagues or customers as proof of being able to use vibration analysis to evaluate the condition of a machine or system and to diagnose machine problems.

1 There are three certification stages. Product manufacturers or employers can offer first-party certifications. Training centers implement second-party certifications. Third-party certifications may be carried out only by independent certification associa-tions accredited in accordance with ISO 17024 and therefore are the most important at the international level.

The internationally recognized certificate for vibration experts

11

A monitoring camera in a new ferry simply fell down from its wall mount. After the camera was re-mounted, in-creased vibrations were detected in the wall between the machine room and the electrical room. The first assumption was that the gearbox must be responsible. Structure-borne sound and orbit analyses

Alignment application

Alignment errors on generator of an express ferryDr. Edwin Becker, Ismaning

Better balancing of generators reduces the excitation potential for rotational disturbing vibrations and for natural vibrations.

Field balancing of generators has become very easy with measurement hardware from PRÜFTECHNIK. For ex-ample, VIBXPERT® is now sold by the market leader for stationary balancing stands under the name SmartBalancer.

Condition Monitoring Application

Field balancing of generatorsChristian Pfaller, Ismaning

One challenge in many balancing processes is to find suitable locations for mounting the balancing weights. The figures show generators in which the balancing weights were easy to mount, because the design was already prepared by the manufacturer for this task.

But this is not always the case. Our balancing specialists still have too many service calls in which field balancing is

Fig. 1: Views of open generators on which balancing weights were easily attached and VIBXPERT® vibration analyzer (top right) with balancing screen.

possible only by attaching additional weights to the coupling. More generator manufacturers should provide means during the construction of the generator for mounting additional weights in the field.

were used to measure rotational vibra-tions, which – despite highly flexible cou-plings – indicated an alignment problem between the gearbox and the generator. To use an alignment system, the inter-mediate wall first had to be opened. The laser alignment system OPTALIGN® Plus then showed extreme angular misalign-

ment in the vertical axis and required the generator to be lowered. The actual cause of the alignment error then came to light during readjustment: the base frame of the generator was deformed, which made it impossible to lower the generator. The base frame had to be modified accordingly.

Fig. 1: View of ferryFig. 2: Laser optical and displacement-based alignment control

12

Dates

Corporate informationPRÜFTECHNIK Condition Monitoring GmbH85737 IsmaningPhone: +49 89 99616-0Fax: +49 89 99616-341eMail: info@pruftechnik.com

PRÜFTECHNIK Alignment Systems GmbH85737 IsmaningPhone: 089 99616-0Fax: 089 99616-100eMail: info@pruftechnik.com

www.pruftechnik.com

All trade fair, seminar and other dates of the PRÜFTECHNIK group can be found on our website at www.pruftechnik.com

Globally and in your area

PRÜFTECHNIK has 20 subsidiaries and about 70 sales agencies around the world.

LIT

01.4

20-1

4.en

500 employees worldwide celebrate:

40 years of PRÜFTECHNIK – how it all began

The marketing program of PRÜFTECH-NIK, founded in 1972 by Dieter Busch, was modest in the beginning, focusing on Swedish bearing monitoring instru-ments. But after only a few years the successful distributing company grew and established its own development and production departments.

In 1984 came the international break-through with the world’s first laser opti-cal shaft alignment system OPTALIGN®. Other milestones and international dis-tinctions followed, which consolidated PRÜFTECHNIK’s reputation as an inno-vative high-tech company.

Today PRÜFTECHNIK has more than 500 employees, with 20 subsidiar-

1984: OPTALIGN® laser optical shaft alignment system as a global innova-tion.

ies and agencies in more than 70 countries world-wide. Measuring technol-ogy from PRÜFTECHNIK is used around the globe in the maintenance departments of virtually every industrial sector – from power plants to dairies, chemical giants and office buildings – to en-sure longer running times, higher product quality and better protection of the environment.

The family-operated company, mean-while in the second generation under the management of Dr. Sebastian Busch, has positioned itself as a stable ma-

The beginnings

jor player in the industry. Neverthe-less, it has remained mid-sized and tradition-conscious with streamlined structures that allow flexible and efficient operations.

Company Founder Dieter Busch Executive Director Dr. Sebastian Busch

From 1976: EDDYCHEK® eddy current test instruments for non-destructive test-ing of semi-finished products.

From 1982: EDDYTHERM® inductive heating units for shrink fitting of roller bearings.

From 1993: VIBROTIP® – with five measuring functions, data memory and OMNITREND® PC software.