86497 Interface Module

86497InterfaceModule

User Guide

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Bently Nevada Corporation has attempted to identify areas of risk createdby improper installation and/or operation of this product. These areas ofinformation are noted as CAUTION for your protection and for the safeand effective operation of this equipment. Read all instructions before

installing or operating this product. Pay particular attention to those areasdesignated by the following symbol:

CAUTION

Bently Nevada Part No. 86947-01 MM First Printing: April 1990Revision E MM December 1999

Copyright© 1990, 1991, 1993, 1999 Bently NevadaCorporation

All Rights Reserved

REBAM®, Keyphasor®, and ADRE® 3 registered trademarksof Bently Nevada Corporation.

No part of this publication may be reproduced, transmitted, stored in aretrieval system, nor translated into any human or computer language, inany form or by any means, electronic, mechanical, magnetic, optical,chemical, manual or otherwise without prior written permission of thecopyright owner.

Bently Nevada CorporationP.O. Box 157

Minden, Nevada 89423 USATelephone 800-227-5514 or 775-782-3611

Fax 775-782-9259

Copyright infringement is a serious matter under United States of America and foreign copyrightlaws.

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FOREWORDThis manual describes installation, maintenance, andspecifications of the 86497 Interface Module. This manual isaddressed to plant engineers, plant operators, serviceengineers, and technicians.

CAUTION

If seismic measurements are being madefor overall protection of a machine,thought should be given to the usefulnessof the measurement for each application.Most common machine malfunctions,such as unbalance and misalignment,occur on the rotor and originate as anincrease or change in rotor vibration. Inorder for any seismic measurement aloneto be effective for overall machineprotection, a significant amount of rotorvibration must be faithfully transmitted tothe machine casing or mounting locationof the transducer.

86497 Interface Module

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CONTENTS

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Section 1System Overview

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Electrical Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Materials List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Section 2Installation

Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Input Signal Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Output Signal Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Power Input Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9GSI 122 Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Section 3Maintenance

Corner Frequency Selection . . . . . . . . . . . . . . . . . . . . . . . 14


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Appendix A

Monitor Modifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Appendix B

Spare Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix CSpecifications

Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Physical Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Electrical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Ok Circuit Detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Appendix D

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Machinery Considerations . . . . . . . . . . . . . . . . . . . . . . . . . 18Measurements Considerations . . . . . . . . . . . . . . . . . . . . . 19Direct Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22


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Section 1 SystemOverview

GeneralThe 86497 Interface Module provides monitoring of two Rolls Royceaeroderivative engines by interfacing the Rolls Royce specifiedaccelerometer system with the Bently Nevada 3300 MonitoringSystem. One 86497 Interface Module will condition three channelsof acceleration in accordance with current Rolls Royce monitoringspecifications for the RB211 and AVON engines.

The standard Rolls Royce monitoring specifications require abandpass velocity signal with corners at 40 Hz and 350 Hz. The86497 Interface Module has highpass velocity signal outputs andbuffered acceleration signal outputs for each channel. The additionaloutputs let you measure the vibration signal with diagnosticequipment such as an oscilloscope or ADRE® 3. These signals giveyou machinery information but do not replace the monitoredbandpass velocity signal.

Electrical DescriptionThe 86497 Interface Module powers each transducer with +24 Vdcand detects OK limits for the input acceleration signal. Figure 1shows the signal flow for one channel. The following paragraphsdescribe this flow.

The differential input provides high common mode rejection which isneeded for noise immunity.

The highpass filter has a 40 Hz (35 Hz option) corner frequency witha 48 db /octave rolloff. This corner is the same filter for both thehighpass velocity (H/P VEL) output and the bandpass velocity (B/PVEL) output.


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Figure 1. Block Diagram


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The integrator converts the 5 mV/g (0.51 mV/m/s ) acceleration2

signal to 100 mV/in/s (4 mV/mm/s) velocity signal.

The lowpass filter has a 350 Hz (400 Hz option) corner frequencywith a 24 db/octave rolloff.

The buffer amplifies the input signal sensitivity from 5 mV/g (0.51mV/m/s ) to 10 mV/g (1.02 mV/m/s ).2 2

Materials ListThe 86497 Interface Module is shipped with the following accessory: 1 - 86947-01 Interface Module Manual.

System DescriptionTwo system configurations are possible depending on the enginesbeing monitored. The AVON engine requires two channels ofmonitoring, and the RB211 engine requires three. Figure 2 showsthe typical system configuration for an RB211 engine. For theappropriate 3300/15 monitor modification refer to Appendix A.


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Figure 2. Typical System Configuration


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Section 2Installation

MountingDetermine the mounting location for the 86497 InterfaceModule and the necessary hardware (see figure 3 formounting dimensions). It is preferable to mount the 86497Interface Module within ten feet (3 metres) of the monitor(s)and GSI 122 for minimum signal degradation.

Input SignalCablingThe input signal originates from the Rolls Royce specifiedacceleration system which consists of the CE 134accelerometer and the GSI 122 galvanic separation interface.The manual for this system shows how to connect the CE 134to the GSI 122. Figure 4 shows how to connect the GSI 122to the 86497 Interface Module. The recommended cable is 18awg twisted pair shielded.

OutputSignalCablingThe output signal cabling connects the 86497 InterfaceModule to the Signal Input Relay Module behind the 3300/15Monitor. Figure 5 shows the proper connection between thetwo instruments. Again, the recommended cable is 18 awgtwisted pair shielded.


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Figure 3. Mounting Dimensions


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Figure 4. Cabling Example


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Figure 5. Cabling Example


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Figure 6. Power Connections Examples

Power Input CablingPower cables are not specified. Figure 6 shows theappropriate connections on the 86497 Interface Module.

CAUTION

To prevent safety violations fromimproper wiring, be sure to follow allapplicable electrical codes whenpower connections are made.

CAUTION

If the D.C. power supply is being used,input voltages over +40 Vdc maycause permanent damage to the86497 Interface Module


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Figure 7. Potentiometer Locations (P1,P2)

GSI 122 AdjustmentThe 86497 Interface Module requires an output signal from theGSI 122 of between 7 and 8 Vdc. Use a voltmeter to measurethe voltage between terminal 1 (Signal) and 2 (0V) on the GSI122. If the voltage is not between 7 and 8 Vdc, usepotentiometer P2 on the rear panel of the GSI 122 to adjustthe voltage. This adjustment is not always required. P1 isfactory set and should not be adjusted. (Refer to figure 7).


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VerificationUse this procedure to verify operation of the 86497 InterfaceModule. This test uses a function generator to simulate avibration signal input and a true rms voltmeter or oscilloscopeto measure the output of the 86497 Interface Module.

1. Disconnect the transducer wiring from channel 1.

2. Connect the test equipment as shown in Figure 8.

3. Set up the function generator with a +7.5 Vdc offsetand a 200 Hz sine wave. Choose a vibration level fromTable 1 and input the appropriate rms or peakamplitude.

4. Verify that the output on the voltmeter or oscilloscopeis within ± 5% of that shown in Table 1.

Note: The highpass velocity output should be the same asthe bandpass velocity output. The acceleration output shouldbe 2 times the signal input.

5. Repeat steps 1 through 4 for channels 2 and 3.

Note: Vpk = Vpp/2 = V rms/.707


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Table 1Verification Signal Levels

VibrationLevel

Input Output

rms(mV) peak(mV) rms(mV) peak(mV)

2 in/s pk 23.0 32.6 141 200

3 in/s pk 34.5 48.9 212 300

50 mm/s pk 22.6 32.0 139 197

75 mm/s pk 34.0 48.1 209 295

2 in/s rms 32.6 46.0 200 283

3 in/s rms 48.9 69.1 300 424

50 mm/s 32.0 45.3 197 278rms

75 mm/s 48.1 68.0 295 418rms


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Figure 8. Verification Example


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Section 3Maintenance

CornerFrequencySelection

CAUTION

To prevent electrical shock,disconnect power from the 86497Interface Module before performingmaintenance.

Select, as required, the highpass and lowpass cornerfrequencies by setting jumpers on the 86498-01 board. Thehighpass options are 40 Hz (standard) and 35 Hz, and thelowpass options are 350 Hz (standard) and 400 Hz. To selectthe different options install the white header across theappropriate jumper, indicated by letter A or B. Refer to Table2:

Table 2. CornerFrequencyOptions

OPTION CHANNEL 1 CHANNEL 2 CHANNEL 3

Highpass W100B W200B W300B35 Hz W108B W208B W308B

to to to

Highpass W100A W200A W300A40 Hz W108A W208A W308A

to to to

Lowpass W109B W209B W309B350 Hz W112B W212B W312B

to to to

Lowpass W109A W209A W309A400 Hz W112A W212A W312A

to to to


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Appendix AMonitorModificationsThe following are the modification numbers to the 3300Monitor with a brief description:

Table 3. Peak ReadoutOptions

Modification Description

156497-01 Dual Channel 3300/16 monitor with Englishmeter scales from 0 to 3 in/s pk

156501-01 Dual Channel 3300/16 monitor with Englishmeter scales from 0 to 3 in/s pk

156499-01 Single channel 3300/16 monitor with Metricmeter scales from 0 to 75 mm/s pk

156503-01 Single channel 3300/16 monitor with Metricmeter scales from 0 to 75 mm/s pk

Table 4. RMS ReadoutOptions

Modification Description

156328-01 Dual channel 3300/26 monitor with Englishmeter scales from 0 to 2 in/s rms

156332-01 Single channel 3300/26 monitor with Englishmeter scales from 0 to 2 in/s rms

156330-01 Dual channel 3300/26 monitor with Metricmeter scales from 0 to 50 mm/s rms

156333-01 Singe channel 3300/26 monitor with Metricmeter scales from 0 to 50 mm/s rms


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Appendix BSpare PartsBently Nevada recommends ordering identical units for spareparts; however, the manual can be purchased separately ifneeded. Part number 86947-01 is the 86497 Interface ModuleManual.

AppendixCSpecifications

Environmental

TemperatureStorage: -4 to +158EF

(-20 to +70 EC)

Operating: +32 to +140EF(0 to +60 EC)

Humidity: 5% to 90%noncondensing

Electrostatic Discharge: 10k through 1000 S

PhysicalInterface

Mounting Size: 12.48 x 7.6 x 3.12 in(317 x 193 x 79.2 mm)

Overall Size: 12.06 x 9.12 x 3.75 in(306 x 232 x 95.3 mm)

Weight: less than 5 lbs (2.27 kg)


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ElectricalPower Input

A.C. option: 85 to 265 Vac,at 47 to 440 Hz

D.C. option: +20 to +34 Vdc

Transducer power input: -23 to -24.5 Vdc

Power Output +22 to +25.5 Vdc,per Channel: at 80 mA

SensitivityInput: 5 mV/g (0.51 mV/m/s )2

OutputB/P VEL andH/P VEL: 100 mV/in/s (4 mV/mm/s)ACC: 10 mV/g (1.02 mV/m/s )2

Corner Frequencies

High Pass: 35 and 40 Hz,at 48 db/octave rolloff

Low Pass: 350 and 400 Hz,at 24 db/octave rolloff

OK CircuitDetectThe OK circuit detect defines a window of OK operation for thetransducer. If the input to the interface module is outside ofthe OK window listed below, the output will be driven to 0 Vdcwhich is not OK for a 3300 monitor. To return to an OKcondition the input to the interface module must be within theOK Recover window listed below.

OK: 5.03 V to 11.87 V nominalOK Recover: 5.53 V to 11.86 V nominal


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Appendix DConsiderations When Using Aeroderivative Gas TurbineMonitoring Systems

IntroductionBently Nevada aeroderivative gas turbine monitoring systemsare designed using specifications established by the enginemanufacturers. These specifications require seismic vibrationtransducers which have limitations. Monitoring systems whichare based solely on casing or bearing housing seismicmeasurements cannot provide information to protect againstcertain types of engine malfunctions. This appendix lists theselimitations and describes options that can enhance theseismic based systems.

MachineryConsiderationsMost common machine malfunctions, including unbalanceand misalignment, originate at the rotor and cause a changein shaft vibration. The extent to which this vibration may betransmitted to the bearing housings and machine casingdepends upon the machine's transfer ratio. Using seismictransducers to monitor the effects of shaft vibration requiresthat the transfer ratio be large and relatively constant withvarying machine speed. Experience has shown thattransmission of shaft vibration is not constant along the rotorspan or machine frame and may vary due to the nature of thevibration source and machine speed.

Seismic measurements, although useful for detecting somemachine problems, provide only an indirect indication of shaftvibration. They are not ideal for rotor monitoring purposesand offer limited information for rotor behavior diagnostics.

Rotor vibration occurs typically in the frequency range of 25


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Hz (1500 cpm) to 400 Hz (24,000 cpm). Turbine bladepassage vibration exists at much higher frequencies, typically5 kHz (300,000 cpm) to 15 kHz (900,000 cpm). Blade passagevibration routinely causes very high acceleration amplitudes,typically 10 to 100 times higher than the levels from rotorvibration sources.

MeasurementConsiderationsWhen seismic transducers are specified, the high temperatureaccelerometer is the type that has demonstrated the bestability to survive the temperature and vibration environment ofaeroderivative gas turbines. This transducer, however, has itsown set of limitations.

As stated, blade passage vibration acceleration amplitudesare typically 10 to 100 times higher than those from rotorvibration sources. Reliably extracting the small rotor vibrationsignals from the high amplitude blade vibration signals is noteasy. The monitoring system must have a wide dynamic rangeto prevent saturation by blade passing frequency vibration.Both signal integration and special filtering are needed whichmakes the monitoring system complex. Because of thiscomplexity, the system is more susceptible to false alarmsand/or missed detection of a real machine malfunction.

To achieve reliable machine information, a vibrationmonitoring system must be simple. Direct measurement ofrotor vibration can play an important role in achieving thisreliability because it allows the monitor to be simple and thusmore reliable.

DirectMeasurementsBently Nevada offers vibration monitoring systems foraeroderivative gas turbines that use displacement transducersto observe the shaft or the outer ring of the bearing. Thesesystems provide more complete machinery vibrationinformation than seismic transducer based monitoring


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systems. These monitoring systems do not need the widedynamic range, special filtering, and electronic integrationrequired by seismic systems. As a result, they are simpler andmore reliable.

Direct measurements do not depend on a transfer ratio whichis seldom constant. Since displacement is being measured, awide dynamic range is not required to prevent saturation byblade passing frequency vibration. This is because bladepassing frequency vibration, even though it has highacceleration amplitudes, has low displacement amplitudes. Asan example, 50 g (490 m/s ) acceleration at 10 kHz (600,0002

cpm) is only 9.78 Fin (0.248 Fm) displacement.

These displacement systems are based on proximity probesspecially developed for this application. The probe tip andbody operate at temperatures up to 500EF (260 EC).

Probe cables are available in two types. One is a flexible cablethat will operate at temperatures up to 482 EF (250 EC). Thiswithstands the temperatures normally encountered exiting thecompressor portion of the turbine. The other is a semirigidcable that operates at temperatures up to 1800EF (982EC).This withstands the temperatures often encountered whenexiting the turbine through the hot gas path. Thesetransducers overcome most of the temperature problems thatare encountered with installation of proximity probes inaeroderivative gas turbines.

Rotor support in aeroderivative gas turbines is provided byrolling element bearings. Many gas turbines utilize squeezefilm dampers. Standard sensitivity proximity probes are veryeffective in measuring shaft vibration in these cases. Aproximity probe can observe either the shaft near the bearingor the outer ring of the bearing. The motion of the outer ringof a squeeze film damped bearing is essentially the motion ofthe shaft because virtually all of the shaft motion appears


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across the damper.

Direct shaft relative measurements with standard sensitivityproximity probes are also useful with rigidly mountedbearings, especially when made several shaft diameters awayfrom the bearings.

In the case of rigidly mounted rolling element bearings, amonitoring system is available that uses a special highsensitivity proximity probe transducer system called REBAM®(Rolling Element Bearing Activity Monitor). The REBAMproximity probe directly measures the small deflections in theouter ring of a rolling element bearing. In addition to providingrotor related information, REBAM is useful in detecting bearingfailure.

Proximity probes can also be used to provide aonce-per-revolution (Keyphasor®) signal. This is very usefulin balancing and rotor diagnostics.

SummarySeismic transducers have limitations. One must understandand consider these limitations when specifying seismictransducers exclusively for monitoring aeroderivative gasturbines. Direct reading shaft or REBAM probes overcomemany of these limitations and can provide superiorperformance. Bently Nevada Corporation is ready to help youengineer and install the proper combination of vibrationmeasurements to provide a reliable and effective monitoringsystem for your aeroderivative gas turbine.


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86497 Interface Module

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