Description
The Bently Nevada 990-05-50-01-00 is a two-wire, loop-powered vibration transmitter in the Bently Nevada 990 Series, designed to convert the raw eddy-current displacement signal from a 3300 NSv non-contacting proximity probe into an industry-standard 4–20 mA signal proportional to shaft vibration amplitude. It is a compact conditioning and scaling device for machinery control systems, not a full monitoring system — its purpose is to deliver a clean, proportional vibration value to a PLC, DCS, or machinery-protection logic without the complexity and cost of a multi-channel monitor. The 990-05-50-01-00 is built for OEMs and plants that need dependable overall vibration trending on small and mid-size rotating equipment.
Application Scenarios
An OEM building packaged centrifugal air compressors was equipping a new skid for a natural-gas gathering plant. The customer’s control philosophy required a single 4–20 mA vibration signal per compressor that could drive an alarm in the existing DCS — there was no provision for a dedicated machinery monitor, and the end user did not want to pay for or maintain one. The OEM’s challenge was to provide a traceable shaft-vibration value from a non-contact probe without adding an external Proximitor, a separate power supply, or a conditioning card in the panel. They specified the 990-05-50-01-00 because it integrates the Proximitor function internally, accepts the 3300 NSv probe and matching extension cable over a 5.0 m system length, and mounts on 35 mm DIN rail. The skid shipped with one transmitter per monitored radial position, and the DCS received a calibrated 4–20 mA signal with no additional interface hardware.
In a second case, a plant had three small process pumps whose original monitoring electronics had failed. The pumps were not classified as critical machinery, so a full monitor upgrade was difficult to justify, but the maintenance team still needed a rising vibration trend to time bearing inspections. They installed a 990-05-50-01-00 at each pump, snapping the units onto the existing DIN rail inside the local junction box and reusing the original shielded twisted-pair home run to the PLC analog input. The Not OK / Signal Defeat circuit prevented false high-vibration alarms when a probe connection loosened during a cable pull, and the maintenance planner gained a usable trend without a capital project.
Parameter
| Parameter | Value / Description |
|---|---|
| Product Model | 990-05-50-01-00 |
| Manufacturer | Bently Nevada (Baker Hughes) |
| Product Type | 2-Wire Vibration Transmitter |
| Product Series | Bently Nevada 990 Series |
| Suffix 05 — Full Scale | 0–5 mils peak-to-peak (0–125 µm pp) |
| Suffix 50 — System Length | 5.0 metres / 16.4 ft total calibrated system length |
| Suffix 01 — Mounting | 35 mm DIN rail clips (installed) |
| Suffix 00 — Agency Approval | Not required |
| Measurement Principle | Eddy-current, non-contacting proximity probe |
| Compatible Probe | Bently Nevada 3300 NSv proximity probe with matching extension cable |
| Input | Proximity probe signal; linear working gap 0.5–1.75 mm (20–55 mils) |
| System Sensitivity | 7.87 V/mm (200 mV/mil) |
| Output Signal | 4–20 mA DC, proportional to peak-to-peak vibration amplitude |
| Powering Method | 2-wire loop-powered |
| Supply Voltage | +12 to +35 VDC |
| Accuracy | ±1.5 % of full-scale range |
| Frequency Response | 5 Hz to 6,000 Hz (+0 / −3 dB) |
| Maximum Loop Resistance | 1,000 Ω (including cable resistance, at 35 VDC) |
| Current Limit | Approx. 23 mA |
| Fault Current | <3.6 mA (probe fault / Not OK indication) |
| Diagnostic Output | Non-isolated PROX OUT and COM terminals + coaxial connector |
| Calibration | Non-interacting zero and span potentiometers under label cover |
| Test Input | Test Input pin for function-generator loop verification |
| Minimum Target Size | 9.5 mm (0.375 in) diameter, AISI 4140 calibration target |
| Operating Temperature | −35 °C to +85 °C |
| Storage Temperature | −51 °C to +100 °C (approx.) |
| Humidity | 100 % condensing, non-submerged |
| Construction | Fully potted sealed circuit, industrial housing |
| Mounting | 35 mm DIN rail clips |
| Dimensions | Approx. 76 × 102 × 51 mm (H × W × D) |
| Net Weight | 0.43 kg (0.95 lb) |
| Place of Origin | USA |