Bently Nevada 990‑04‑50‑01‑00 Two‑Wire Vibration Transmitter

Description

Hardware & Electrical Specifications

‑ Manufacturer: Bently Nevada (Baker Hughes) ‑ Functional Type: 2‑Wire Loop‑Powered Vibration Transmitter ‑ Compatible Sensor: 3300 NSv proximity probe + matching extension cable ‑ Total System Length: 5 meters ‑ Measurement Range: 0‑100 μm peak‑to‑peak shaft vibration ‑ Frequency Response: 5 Hz ~ 6000 Hz ‑ Power Supply: 12‑35 VDC loop power, two‑wire 4‑20 mA output ‑ Output Signal: 4 mA = 0 μm; 20 mA = 100 μm peak‑to‑peak ‑ Diagnostics: NOT‑OK signal defeat circuit; PROX‑OUT coaxial test port for raw gap‑voltage / vibration waveform ‑ Adjustment: Internal zero and span potentiometers for field calibration ‑ Test Feature: Test‑input terminal for functional injection testing ‑ Connectors: Screw terminals for loop power/output; coaxial probe input; PROX‑OUT BNC diagnostic port ‑ Mounting: 35 mm DIN‑rail clip or bulkhead screw mounting ‑ Housing: Fully potted sealed construction, withstands high‑humidity condensing environment ‑ Certifications: CSA, ATEX / FM Division 2 hazardous‑area approval ‑ Hot‑swap: Non‑hot‑swappable; de‑energize loop circuit before replacement

Environmental Specifications

‑ Operating Temperature: ‑35 °C ~ +85 °C ‑ Storage Temperature: ‑40 °C ~ +85 °C ‑ Relative Humidity: 5 %‑100 % condensing permitted (potted encapsulation) ‑ Vibration & Shock: Complies with industrial rotating‑machinery cabinet EMI and transient requirements

Mechanical Data

‑ Weight: approx 0.7 kg

Core Functions

1. Integrated proximitor & vibration conversion: Receives eddy‑current probe signal, computes peak‑to‑peak shaft radial vibration value, outputs standard 4‑20 mA analog signal to plant DCS/PLC system.
2. Fault‑defeat protection: NOT‑OK circuit holds safe low‑mA output when probe, cable or connection fails, preventing false high‑vibration nuisance alarms.
3. Field calibration capability: Zero‑span potentiometers allow on‑site loop calibration without removing unit from cabinet.
4. Diagnostic test interface: PROX‑OUT BNC port outputs raw gap‑voltage and dynamic vibration waveform for oscilloscope troubleshooting.
5. Flexible installation: Supports DIN‑rail or bulkhead mounting, suitable for compressor, pump and motor local cabinet installation.

Installation, Replacement & Critical Warnings

1. De‑energize the 4‑20 mA loop power before replacement; unit is two‑wire loop‑powered, non‑hot‑swappable.
2. Must use 5‑meter total length NSv probe‑cable assembly; wrong system length will cause measurement drift.
3. Adjust probe target gap to recommended mid‑gap position during commissioning; verify gap‑voltage via PROX‑OUT port.
4. After installation, perform zero‑span calibration; confirm 4‑20 mA output corresponds to actual vibration reading in control system.

5. Common failure mode: Coaxial probe‑cable damage, surge damage to internal proximitor circuit. Investigate probe installation and cabling when NOT‑OK status occurs.