Overview
The Bently Nevada 990-04-50-01-CN, also cataloged as the 990 vibration measurement transmitter, conditions a compatible proximity-probe signal into peak-to-peak vibration amplitude and transmits a proportional 4-20 mAdc two-wire output to a machinery-control system.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 990-04-50-01-CN |
| Brand | Bently Nevada |
| Product Type | Vibration Measurement Transmitter |
| Full-Scale Range | 0-4 mils peak-to-peak |
| Calibrated System Length | 5 m |
| Standard Transducer Input | One 3300 NSv probe and matching extension cable |
| Signal Output | 4-20 mAdc, two-wire loop |
| Transmitter Supply | +12 to +35 Vdc at transmitter terminals |
| Maximum Loop Resistance | 1000 ohm including cable at 35 Vdc |
| Typical Current Limiting | 23 mA |
| Zero and Span | Non-interacting external adjustments |
| Not OK Output | Less than 3.6 mA within 100 microseconds |
| Not OK Recovery | 2-3 seconds after fault removal |
| Mounting Option | 35 mm DIN rail clips |
| Operating Temp | -35 to +85 deg C |
| Storage Temp | -52 to +100 deg C |
Eddy-Current Probe Signal Scaling
The 990-04-50-01-CN accepts the signal from one compatible 3300 NSv probe and matching extension cable. The transmitter conditions the probe-system signal according to the selected 5 m calibrated system length and 0-4 mils peak-to-peak full-scale range.
Therefore, the probe, extension cable, calibrated system length, and transmitter configuration must correspond to the installed measurement chain. The transmitter then converts the conditioned vibration measurement into a 4-20 mAdc two-wire loop signal for the receiving machinery-control system.
The transmitter also provides a Not OK current indication. It drives the output below 3.6 mA within 100 microseconds when the specified fault condition occurs, then restores normal operation 2-3 seconds after fault removal.
Frequently Asked Questions
Q: What transducer configuration does the 990-04-50-01-CN accept?
A: The specified input configuration uses one 3300 NSv probe with its matching extension cable. The complete probe system must match the transmitter configuration.
Q: What supply voltage does the transmitter require?
A: The transmitter operates from +12 to +35 Vdc measured at the transmitter terminals. At 35 Vdc, the maximum loop resistance is 1000 ohm including cable.
Q: How does the transmitter indicate a Not OK condition?
A: The transmitter drives the output below 3.6 mA within 100 microseconds. After the fault clears, the specified recovery time is 2-3 seconds.
Field Installation Guidelines
Mount the transmitter using the specified 35 mm DIN rail clips and secure the module against movement. Wire the two-wire 4-20 mAdc loop with correct polarity and maintain the stated loop-resistance limit.
Connect only the specified 3300 NSv probe and matching extension cable. Verify the calibrated system length and 0-4 mils peak-to-peak range against the installed transducer chain before commissioning.
Route the vibration signal and current-loop wiring away from high-current switching conductors where practical. Follow the installed control-system requirements for cable shielding and shield termination. Do not alter the probe, extension cable, or transmitter configuration without confirming measurement compatibility.
Before energizing the loop, verify the transmitter supply voltage at its terminals and confirm that the receiving control system can interpret the specified 4-20 mAdc signal and the below-3.6 mA Not OK state.
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