Product Overview

The Bently Nevada 990-05-70-01-01​ is a two-wire, loop-powered vibration transmitter from the Bently Nevada 990 Series, designed for machinery builders and end users who need a simple, reliable vibration signal for their control system without installing a full monitoring rack. It accepts input from a single non-contacting 3300 NSv proximity probe and its matching extension cable, conditions that signal into peak-to-peak vibration amplitude, and outputs a proportional 4–20 mA current loop that any PLC, DCS or SCADA analogue input card can read directly.The engineering value of the Bently Nevada 990-05-70-01-01​ lies in its integration. A conventional installation requires a Proximitor sensor, a monitor channel and a separate transmitter; here the proximity driver and the 4–20 mA conversion live in one compact, potted housing that mounts on a 35 mm DIN rail. That means fewer components in the panel, fewer terminations to fail, and a vibration point that costs a fraction of a rack-based channel — which is exactly why the 990 was aimed originally at OEMs of centrifugal air compressors, small pumps, motors and fans.This particular variant is configured for a 0–5 mils peak-to-peak (0–125 µm pp)​ full-scale range with a 7.0 metre (23.0 ft)​ total electrical system length, uses 35 mm DIN rail clips​ for mounting, and carries CSA Division 2​ hazardous area approval. Beyond the 4–20 mA output, the Bently Nevada 990-05-70-01-01​ provides a buffered PROX OUT signal through a coaxial connector for portable diagnostic instruments, non-interacting zero and span potentiometers for field calibration, and a Not OK / Signal Defeat circuit that drives the loop below 3.6 mA within 100 µs if the probe fails, so a broken lead cannot masquerade as a high-vibration alarm.

Technical Specifications

Main Features and Advantages

Integrated Proximitor eliminates a separate box: The Bently Nevada 990-05-70-01-01​ contains the proximity probe driver as well as the 4–20 mA converter, so there is no external Proximitor to mount, wire and power. For an OEM building a compressor skid or a pump package, that removes a component, a set of terminations and a potential failure point from every vibration point on the machine.Fault detection that prevents false trips: If the probe lead breaks or the probe drifts out of its gap window, the Not OK / Signal Defeat circuit in the Bently Nevada 990-05-70-01-01​ drives the loop below 3.6 mA within 100 microseconds. Downstream, the PLC or DCS sees an unmistakable under-range condition rather than a plausible-looking high vibration value, which is the difference between a correctly diagnosed instrument fault and a spurious machine trip. A power-up inhibit holds the output low for two to three seconds at start-up, suppressing the transient spikes that would otherwise pollute the trend during energisation.Field calibration without special tools: Non-interacting zero and span potentiometers sit under the transmitter label, so the loop can be trimmed on site against a known reference, and the two adjustments do not fight each other. A Test Input pin lets a technician inject a function generator signal and verify the whole loop quickly, without disturbing the machine or removing the probe.Diagnostics on tap: The buffered PROX OUT coaxial connector on the Bently Nevada 990-05-70-01-01​ delivers the raw dynamic vibration and gap voltage signal at 200 mV/mil, so a portable analyser or oscilloscope can be connected for detailed fault diagnosis while the 4–20 mA loop continues to feed the control system. Bently Nevada recommends a 990/991 Test Adapter when using AC-powered instruments, since the buffered output is not isolated from the loop.Built for wet, hostile locations: The potted construction of the Bently Nevada 990-05-70-01-01​ is rated for up to 100% condensing humidity, which matters in cooling tower basins, pump houses, offshore skids and washdown areas where ordinary electronics fail. Combined with a −35 °C to +85 °C operating range, DIN rail or bulkhead mounting, CSA Division 2 approval and compatibility with the compact 3300 NSv probe — designed for the tight clearances inside c