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Operation Manual Bently Nevada™ Asset Condition Monitoring Accelerometer Interface Module Part Number 88301-01 Rev. H (08/07)
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Bently Nevada, Keyphasor, Proximitor Contact Information The following ways of contacting Bently Nevada are provided for those times when you cannot contact your local representative: Mailing Address 1631 Bently Parkway South Minden, Nevada USA 89423 Telephone 1.775.782.3611 1.800.227.5514 1.775.215.2873 Internet www.ge-energy.com/bently...
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Additional Information Notice: This manual does not contain all the information required to operate and maintain the product. Refer to the following manuals for other required information. 3300 System Overview (Part Number 80171-01) 3300 System Installation Instructions (Part Number 80172-01) 3300 System Troubleshooting (Part Number 80173-01) 3300/95 Filter Module/Vibration Monitor Operation Manual (Part Number 88060-01)
Section 1 - INTRODUCTION 1. INTRODUCTION The 86517 Accelerometer Interface Module is a component in accelerometer- based transducer systems commonly used for vibration monitoring of aeroderivative gas generators and gas turbines. The interface module is designed for use with the Bently Nevada 3300 series 3300/95 Filter Module/Vibration Monitor and can also be used with specially modified 3300 monitors such as the 3300/15 and 3300/25.
Accelerometer Interface Module Operation Manual 2. SYSTEM OVERVIEW The accelerometer-based transducer system consists of a high temperature charge-coupled accelerometer; rugged, low-noise, high temperature extension cable(s); and the accelerometer interface module as shown below. Figure 1.1 Transducer System...
Section 2 - SYSTEM OVERVIEW 2.1 Accelerometer Interface Module A functional block diagram of the interface module is shown below: Figure 1.2 Interface Module Block Diagram The accelerometer interface module performs the following functions: Converts a charge input from the accelerometer to a voltage acceleration signal.
Accelerometer Interface Module Operation Manual The differential charge output of the accelerometer enters the interface module through pins C and A of the three-pin locking connector while pin B connects to the extension cable inner shield and to the interface module case. The charge amplifier converts the differential charge input to a low impedance voltage signal and the subsequent scaling stage adjusts the sensitivity to 10 mV/g pk (1.02 mV/m/s...
Section 2 - SYSTEM OVERVIEW capacitance of the accelerometer plus the distributed cable capacitance should not exceed 8300 picofarads. Cable drawings and schematics are in the appendix. 2.3 Accelerometer For aeroderivative gas turbines, the accelerometers are typically provided with the engine either by the manufacturer or the packager and must be qualified by the engine manufacturer.
Accelerometer Interface Module Operation Manual 3. INSTALLATION 3.1 Receiving, Inspecting, and Handling Carefully remove the interface module, extension cable and accelerometer (if applicable) from their shipping containers and inspect them for shipping damage. If you remove the lid, be careful not to lose the two mounting screws located in the base of the interface module enclosure.
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Section 3 - INSTALLATION Connect the extension cable tightly to the accelerometer and safety wire the connector. A major cause of nuisance alarms is a loose connection to the accelerometer. Route the extension cable away from the turbine, and in the case of steam injection turbines, away from any steam manifolds.
Accelerometer Interface Module Operation Manual Accelerometer If you are installing the Bently Nevada accelerometer (P/N 45357-01) then follow these directions: Contact the turbine manufacturer or your original equipment manufacturer (OEM) for instructions on mounting the accelerometer. The correct mounting location and mounting structures, such as brackets and fasteners, are critical to the performance of the transducer system.
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Section 3 - INSTALLATION Refer to drawing 141243 (see appendix) for field wiring connections to 3300 series monitors with internal safety barriers. Notes are referenced in each of the wiring diagrams which address grounding and shielding and making recommendations. Drawings 141243 and 141110 in the appendix are agency approval drawings showing installation and wiring for Division 1 and Zone 1 hazardous areas.
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Accelerometer Interface Module Operation Manual Figure 2.2 Field Wiring to 3300/95 Monitor without Barriers (Notes on following page)
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Section 3 - INSTALLATION Notes for Figure 2.2 The accelerometer case is connected to the machine earth and the differential signal output is isolated. The accelerometer case connects to the extension cable shield through the cable connector for the hardline cable and connects to the outer shield for the softline cable.
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Accelerometer Interface Module Operation Manual Figure 2.3 Field Wiring to 3300 Monitor without Barriers (Notes on following page)
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Section 3 - INSTALLATION Notes for Figure 2.3 The accelerometer case is connected to the machine earth and the differential signal output is isolated. The accelerometer case connects to the extension cable shield through the cable connector for the hardline cable and connects to the outer shield for the softline cable.
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Accelerometer Interface Module Operation Manual Figure 2.4 Field Wiring Interface Module to 3300/95 Monitor with Barriers (Notes on following page)
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Section 3 - INSTALLATION Notes for Figure 2.4 The accelerometer case is connected to the machine earth and the differential signal output is isolated. The installer must ensure that the accelerometer mounting structure has the same ground potential as barrier ground.
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Accelerometer Interface Module Operation Manual MTL 728(-) barrier is recommended for acceleration signal. Power: V 28 V, R = 300 ohms. Barrier ground is the single point earth ground. NOTE: When external barriers are used the jumper between signal common and rack chassis on the 3300 Power Input Module at the rear of the 3300 rack must be removed.
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Section 3 - INSTALLATION Notes for Figure 2.5 The accelerometer case is connected to the machine earth and the differential signal output is isolated. The installer must ensure that the accelerometer mounting structure has the same ground potential as barrier ground.
Accelerometer Interface Module Operation Manual 4. MAINTENANCE This section describes a calibration procedure for the acceleration signal and provides some troubleshooting procedures for the transducer system. To perform these procedures you will need the following tools and instruments: function generator, (50 ohm output) DC power supply multimeter screwdriver...
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Section 4 - MAINTENANCE Connect the Power Supply to the -24Vdc and COM terminals on the interface module as shown and adjust the voltage to -24 Vdc. Connect the multimeter to the +ACCEL terminal. Connect the 0.01 uF capacitor and function generator as shown.
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Accelerometer Interface Module Operation Manual Unscrew the four screws at each corner of the lid. Open the lid and fold it back. Adjust the potentiometer until the multimeter reads 0.3535 ±7.0 Vrms. Close and tighten the lid and verify that the multimeter still reads 0.3535 Vrms. If it does not then repeat steps 6 and 7.
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Section 4 - MAINTENANCE Disconnect the input from pin C and connect it to pin A and leave pins C and B not connected. Verify that the multimeter still reads 0.3535 Vrms ±7.0 mVrms. If it does not then check your test setup as in step 2 and then repeat this step.
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Accelerometer Interface Module Operation Manual Connect the input to pin C and connect the multimeter to the +VELOCITY terminal as shown above. Adjust the function generator to output a sine wave with the frequency and amplitude based on the filter corner frequencies and accelerometer charge sensitivity as shown in the table below: Corner frequency Function Generator Setting...
Section 4 - MAINTENANCE 4.2 Common Mode Rejection Measurement The amount of noise that will appear at the output of the module is directly related to the interface module's ability to reject common mode voltage at its input. To assure that the module's noise floor remains in accordance with the specification by which it was designed, the following common mode rejection measurement is recommended every two years.
Accelerometer Interface Module Operation Manual voltage is between approximately -22 Vdc and -25 Vdc then either the acceleration or velocity field wiring or the interface module is defective. Reconnect the power and common wiring to the interface module but do not connect the signal wiring.
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Section 4 - MAINTENANCE Isolation and Correction: Because this type of problem is usually observed at the monitor, you need to determine if the fault lies with the transducer system, the monitor, or, in the case of 1X filtered monitor channels, with the rotor speed signal. Check the components of the transducer system in the following order: Check all connectors and connections in the signal path.
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Section 5 - ORDERING INFORMATION Weatherproof Housing* 80808 - 01 Housing for two interface modules. 80808 - 02 Housing for four interface modules. * Housings come with 3/4 inch conduit hubs. Conduit and fittings as necessary will need to be procured separately. Accessories 0.01 microfarad capacitor: BNC P/N 00448308 Connector for connection of unterminated extension cables to interface module.
Accelerometer Interface Module Operation Manual 6. INTERFACE MODULE OPTIONS Option AA, Transducer Charge Input Sensitivity This option sets the charge sensitivity of the charge amplifier at 50 pC/g or 100 pC/g. If soldered link W1 on the charge amplifier PWA (printed wiring assembly) is not installed then the 50 pC/g option is selected, when W1 is installed then the 100 pC/g option is selected.
Section 7 - SPECIFICATIONS 7. SPECIFICATIONS The following specifications apply with a -24 Vdc supply voltage, 100 KΩ load, at 77° F (25° C) unless otherwise specified. 7.1 Accelerometer Interface Module POWER Supply Voltage: -23 Vdc to -26 Vdc Current Draw: 22 mA maximum INPUT Acceleration:...
Section 7 - SPECIFICATIONS Mounting: Two 0.16 inch diameter 8 - 32 allen head bolts located at opposite diagonal corners of a 4.45 inch by 2.05 inch (113 mm by 52 mm) rectangle . The interface module must be isolated from ground. 7.3 Extension Cable SOFTLINE CABLE Accelerometer Mating Connector:...
Accelerometer Interface Module Operation Manual Operating Temperatures: Cable -65° F to +1200° F (-54° C to +649° C) Accelerometer mating connector -65° F to +800° F (- 54° C to +427° C) Disconnect interface mating connector -65° F to +800° F (-54° C to +427°C) 7.4 Accelerometer, P/N 45357-01 Sensitivity: 50 pC/g ±5%...
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Accelerometer Interface Module Operation Manual Figure A-1 80808 Weatherproof Housing Description Overall Base Overall Mounting BL x BW L x W G x H Small SST 12.00 in x 12.00 in 13.50 in x 12.94 in 12.75 in x 10.00 in Enclosure (304.8mm x 304.8mm) (342.9mm x 328.7mm) (323.8mm x 254mm) Large SST...