IS200VVIBH1C - Vibration Monitor Board

Functional Description

IS200VVIBH1C Overview

IS200VVIBH1C is a Vibration Monitor Board developed by General Electrics under Mark VI. Vibration probe signals from the TVIB or DVIB terminal board are processed by the Vibration Monitor board. Up to 14 probes can be connected to the terminal board directly. To the VVIB processor board, two TVIB can be connected. VVIB digitizes the various vibration signals and transmits them to the controller over the VME bus. For shaft vibration monitoring, the Mark VI system employs Bently Nevada probes. The vibration probes listed below are compatible:

• Proximity
• Velocity
• Acceleration
• Seismic
• Phase

Vibration Monitoring Firmware

The Vibration Monitoring on the VVIB is divided into three sections:

Channels 1 – 3:

• Position data from Proximitors, wideband vibration data from Proximitors, accelerometers with integrated outputs, Velomitors, and Seismics can all be used on channels 1 through 3. When a Keyphasor probe is utilized, 1X and 2X information can be extracted from Proximitors viewing axial vibration information. In LM applications using accelerometers, tracking filters are commonly employed.

Channels 4–8:

• Position information from Proximitors, wideband vibration information from Proximitors, Velomitors, and Seismics can all be found on Channels 4–8. When a Keyphasor probe is utilized, 1X and 2X information can be extracted from Proximitors viewing axial vibration information.

Channels 9–12:

• Only position information is broadcast on Channels 9–12.

Channel 13:

• Position feedback and Keyphasor feedback are supported by Channel 13.

Wideband Vibration Filtering

• If input channels 14 through 21 are specified as vibration channels, the Wideband Vibration Filtering function runs at 4.6 kHz and 2.3 kHz, respectively. The FPGA that controls the A/D and multiplier circuit provide the vibration input for this purpose. The gap or position filter is a low pass filter with two poles and an 8 Hz cutoff frequency. The Gap Scaling and Limit Check function use the output of the gap filter, which is given in volts.
• The wideband vibration information can be shaped or conditioned based on the FilterType configuration parameter. For the Seismic and Velomitor sensor types, FilterTypes of Low-pass, Band-pass, or High-pass are used. All other sensor types use FilterType as None. Through the Filtrlpattn parameter, the Low-Pass filter can be configured for 2, 4, 6, or 8 pole attenuation behavior. Filtrlocutoff, a 3 dB cutoff frequency, is also adjustable.
• The High-pass filter can also be configured for 2, 4, 6, and 8 poles to sharpen the filter's attenuation characteristics via the Filtrhpattn parameter. The cutoff frequency, Filtrhpcutoff, can be configured.
• Vfout, the wideband filtered vibration output, is subjected to a minimum/maximum peak detect function. For Keyphasor-based speeds greater than 12 rpm, the capture window for the minimum/maximum detect is 160 milliseconds wide. The goal is to collect at least two cycles of vibration data in order to obtain an accurate peak-to-peak calculation. The unfiltered wideband vibration output is subjected to a second minimum/maximum peak detect function.
• Vmax and Vmin outputs are used to clamp the filtered vibration output peak-to-peak.

Diagnostics

• Diagnostics execute a high/low (hardware) input signal limit check as well as a high/low system (software) limit check. In the field, the software limit check can be changed. If one of the X or Y probe pairs exceeds its limitations, a probe fault, alert, or trip condition occurs. Furthermore, if a probe error is discovered based on the dc component, the application software avoids a vibration trip (the ac component).

IS200VVIBH1C Features

• Number of Channels: 26 probes with two TVIB boards
• Probe power:
  • -24 V dc from the -28 V dc bus; each probe supply is current limited
  • 12 mA load per transducer
• Buffered outputs: The amplitude accuracy for the signal to the Bently Nevada 3500 vibration analysis system is 0.1 percent.

Installation

Installation Instructions

• Turn the VME processor rack off.
• To seat the board's edge connectors, slide them in, and push the top and bottom levers in with your hands.
• Tighten the captive screws on the front panel's top and bottom.

Operation

Supported Probes

• Bently Nevada Proximitor, Seismic, Accelerometer, and Velomitor probes are supported by the terminal board. The vibration probes are powered by the VVIB boards in either simplex or TMR mode.

Probe Signal Processing

• The probe signals are returned to VVIB, where they are A/D converted and sent to the controller via the VME bus. For Proximitor power, VVIB supplies -28 V dc to the terminal board. A diode high-select circuit in TMR systems selects the highest -28 V dc bus for redundancy. Individual excitation sources, -23 to -26 V dc, short circuit protected, are provided by regulators.

Sampling and Filtering

• Over discrete time periods, probe inputs are sampled at high speeds of up to 4600 samples per second. The maximum and minimum values are accumulated, the difference (max-min) is used to calculate vibration, and the results are filtered. The resulting peak-to-peak voltage is scaled to produce engineering units (EU) (peak-to-peak) displacement for Proximitors inputs and EU (pk) velocity inputs from accelerometers, integrated outputs, seismics, and Velomitors.