Bently Nevada 86517-xx-xx-01-02 MOD159840-01

Bently Nevada 86517-xx-xx-01-02 MOD159840-01 Accelerometer Interface Module

Product Introduction

The Bently Nevada 86517 Accelerometer Interface Module serves as a vital link between piezoelectric accelerometers and a plant's vibration monitoring system. Specifically, this module processes the charge input from an accelerometer, converting it into a usable voltage signal for analysis. The specific model 86517-01-01-01-02 comes configured with a sensitivity of 50 pC/g and a bandpass filter with corner frequencies at 25 Hz (high-pass) and 350 Hz (low-pass). Furthermore, the module provides both buffered acceleration and velocity outputs. This signal conditioning ensures reliable data transmission over long cable runs, making it an excellent choice for industrial environments. Consequently, this interface module plays a crucial role in predictive maintenance and machine protection strategies.

Technical Specifications

The 86517 Accelerometer Interface Module offers a comprehensive set of technical features designed for precise measurement.

Input and Output

This module accepts a differential input from a piezoelectric accelerometer. For instance, it supports transducers with sensitivities of 50 pC/g pk or 100 pC/g pk. For the acceleration output, it delivers a balanced signal with a sensitivity of 10 mV/g pk (1.02 mV/m/s² pk) and an output impedance of 50 ohms nominal. Meanwhile, the velocity output provides a balanced signal with a sensitivity of 100 mV/in/s pk (3.93 mV/mm/s pk) and a nominal impedance of 100 ohms.

Dynamic Range and Overload

The acceleration output features a typical dynamic range of 750 gs without barriers and 500 gs with barriers. In terms of overload protection, the module handles 50,000 pC peak for accelerometers with 50 pC/g sensitivity and 100,000 pC peak for those with 100 pC/g sensitivity. Additionally, the velocity output offers a dynamic range of 20 in/s pk across the frequency band from 25 Hz to 1000 Hz.

Signal Conditioning and Filters

A 12th-order bandpass filter conditions the acceleration signal, utilizing a Butterworth response with a rolloff of -36 dB/octave. For the 86517-01-01-01-02 variant, the high-pass corner sits at 25 Hz while the low-pass corner is set to 350 Hz. Moreover, the module integrates the filtered acceleration signal to produce a velocity signal, a common requirement for effective machinery monitoring.

Frequency Response

The low-frequency response is governed by the charge amplifier, featuring a -3 dB corner at 4.7 Hz. In contrast, the high-frequency response depends on the combined capacitance of the accelerometer and extension cable. For instance, with an accelerometer capacitance of 1000 pF and a cable capacitance of 1000 pF, the upper -3 dB frequency reaches approximately 5000 Hz.

Accuracy

At 77°F (25°C), the velocity output maintains an accuracy of ±5.0% of the calculated velocity from an ideal input within the passband of the filter. Therefore, this high level of precision ensures reliable vibration data for critical decision-making.

Mechanical and Environmental Specifications

Dimensions and Weight

The module measures 3.00 inches in height, 3.25 inches in width, and 5.50 inches in length. Besides that, it weighs approximately 0.56 kg, making it compact and easy to integrate into existing racks.

Connectors

The accelerometer input connector is an MS-3112-8-3P type. For power and output signals, the module uses an 8-lug terminal block. As a result, these connectors ensure secure and reliable electrical connections in industrial settings.

Operating Environment

This module operates reliably in temperatures ranging from +32°F to +158°F (0°C to 70°C). For storage, it can withstand temperatures from -40°F to +185°F (-40°C to +85°C). Furthermore, it functions in humidity conditions from 0 to 95%, non-condensing.

Power Requirements

The Bently Nevada 86517 requires a supply voltage between -23 Vdc and -26 Vdc. Moreover, its maximum current draw is only 22 mA, making it an energy-efficient component for monitoring systems.

Installation and Wiring Guidelines

Proper installation guarantees optimal performance from the 86517 Interface Module. For the connection between the accelerometer and the module, Bently Nevada recommends using extension cables such as part numbers 45358-07, 45358-09, or 83387-xxx. Alternatively, users may select equivalent cables that meet the required specifications.

For the power, common, and velocity output wiring, the module requires 18 to 22 AWG stranded wire with an insulating sheath and 100% shield coverage. Specifically, Belden 83336 (18 AWG) or Belden 83334 (22 AWG) serve as suitable choices. Meanwhile, the maximum cable length for these connections should not exceed 1000 feet (305 meters).

Additionally, the accelerometer pole-to-pole capacitance combined with the extension cable capacitance must remain below 8300 picofarads. Exceeding this limit may degrade signal quality and affect measurement accuracy.

Packaging List

Each order of the Bently Nevada 86517-01-01-01-02 includes the following items:

• One Bently Nevada 86517 Accelerometer Interface Module (MOD159840-01)

• One 8-lug terminal block connector for power and output signals

• One MS-3112-8-3P connector for accelerometer input

• Product installation and wiring guide

All items ship in anti-static packaging to prevent electrostatic damage during transit.

Shipping Information

We ship all orders via FedEx, UPS, or DHL. Each package includes tracking information for convenient monitoring of your shipment. Typically, standard delivery takes 3 to 5 business days depending on the destination.

Frequently Asked Questions

1. What is the primary application for the 86517 Interface Module?

This module is specifically designed for vibration monitoring systems, particularly with the Bently Nevada 3300/95 monitor. For example, it works effectively with aeroderivative gas turbines and other rotating machinery requiring continuous vibration surveillance.

2. What is the difference between the acceleration and velocity outputs?

The acceleration output provides a raw filtered signal at 10 mV/g pk, while the velocity output delivers an integrated signal at 100 mV/in/s pk. In fact, many monitoring systems utilize the velocity output because it offers a better representation of machinery health for most rotating equipment.

3. Which cable types work best with the 86517-01-01-01-02?

For the accelerometer connection, use Bently Nevada extension cables 45358-07, 45358-09, or 83387-xxx. For power and output wiring, Belden 83336 (18 AWG) or Belden 83334 (22 AWG) are recommended.

4. What is the maximum allowable cable capacitance for this module?

The total capacitance from the accelerometer and extension cable must not exceed 8300 picofarads. Therefore, this limitation ensures proper frequency response and signal integrity.

5. Can this module operate in extreme temperature conditions?

Yes, it operates reliably from 32°F to 158°F (0°C to 70°C). For storage, it can handle temperatures from -40°F to 185°F (-40°C to 85°C). Thus, it is suitable for most industrial environments.