Product Overview

The Bently Nevada 990-04-70-01-00​ is a two-wire, loop-powered vibration transmitter that accepts input from a single non-contacting 3300 NSv proximity probe and converts shaft relative vibration into a proportional 4–20 mA signal for a PLC, DCS or machinery control system. It is built for a specific purpose: giving OEMs and end users of centrifugal air compressors, small pumps, motors and fans a simple, continuous vibration value without the cost, space and configuration burden of a full monitoring rack.Decoding the part number explains exactly what this unit is. In the Bently Nevada 990-04-70-01-00, the 04 designates a full-scale range of 0–4 mils peak-to-peak (0–100 µm pp), which covers the normal vibration band of most small and medium machines; the 70 specifies a 7.0 metre (23.0 foot) total system length, the longer of the two standard calibration options; the 01 selects 35 mm DIN rail clip mounting; and the 00 indicates that no specific agency approval option is required for this configuration.The transmitter integrates the Proximitor sensor internally, so no separate proximitor module or rack slot is needed, and it operates from a +12 to +35 V DC loop supply with a maximum loop resistance of 1000 Ω. Because it is loop powered, only two wires are required at the junction box, which is what makes the Bently Nevada 990-04-70-01-00​ attractive for packaged and skid-mounted equipment where wiring budget is tight.Beyond the 4–20 mA output, the Bently Nevada 990-04-70-01-00​ provides a buffered PROX OUT terminal and coaxial connector carrying the dynamic vibration and gap voltage signal for portable diagnostics, non-interacting zero and span potentiometers for loop trimming, a Test Input pin for quick verification with a function generator, and a NOT OK circuit that drives the output below 3.6 mA within 100 microseconds if the probe or its connection fails.

Technical Specifications