Configured for continuous vibration monitoring in industrial machine protection platforms, the Bently Nevada 991-06-50-02-01 (991 Vibration Transmitter) provides direct physical execution of signal transduction and loop current output.

Suffix Breakdown & Model Matrix

• 991: Vibration Transmitter
• 06: Full Scale Range (50-500 um pk-pk)
• 50: Cable Length (5.0 meters)
• 02: Mounting Option (Bulkhead screws)
• 01: Agency Approval (CSA Division 2)

Hardware Specifications

Mechanical Monitoring & Eddy-Current Validation

The 991 transmitter utilizes an integrated eddy-current probe scaling architecture to convert radial shaft vibration into a proportional 4-20 mA output signal. Accurate performance requires precise gap voltage validation; the transducer must be gapped to the factory-specified -10 VDC target to maintain linearity. Rotor dynamics monitoring is sustained through this conversion, while cross-talk suppression is maintained by ensuring adequate physical separation of the probe tip from adjacent conductive surfaces and other sensors operating at the same carrier frequency.

Ordering Info

• 1x 991 Vibration Transmitter
• 1x Bulkhead mounting kit
• 1x Technical data sheet

Field Installation Guidelines

• Mounting: Secure the transmitter using the provided bulkhead screws on a vibration-free surface to maintain structural integrity.
• Loop Wiring: Ensure the loop resistance does not exceed 1000 Ohm at 35 VDC to maintain signal loop integrity.
• Shielding: Connect signal cable shields to a common instrument ground to minimize EMI and high-frequency noise interference.
• Verification: Measure the transmitter output at the terminals to confirm the 4-20 mA signal corresponds to the calibrated vibration range.

Frequently Asked Questions

• What is the maximum permissible loop resistance?

  The loop resistance must not exceed 1000 Ohm when the transmitter is powered at 35 VDC to ensure sufficient voltage drop for signal operation.

• Can this transmitter be used in hazardous environments?

  Yes, the 01 suffix confirms CSA Division 2 approval, making it suitable for operation in designated hazardous areas.

• What is the standard current output range?

  The transmitter provides a standard 4-20 mA proportional output representing the vibration level within the configured full-scale range.

• How is the transmitter calibrated?

  The transmitter is factory-calibrated for the specified full-scale range (50-500 um pk-pk); field recalibration is not required for standard operation.

• What is the power supply requirement?

  The unit requires a DC voltage between +12 VDC and +35 VDC at the transmitter terminals for correct operation.

• Does the transmitter include the probe?

  The 991 series transmitter is an integrated unit; ensure the probe tip and extension cable integrity are maintained during installation.

• What is the significance of the 23 mA current limiting?

  This safety feature prevents excessive current draw in the event of an internal fault, protecting the power supply loop.

• How should the cable be protected?

  Route the 5.0 meter coaxial cable in grounded metallic conduit to prevent signal degradation and physical damage.