Bently Nevada 3300/50-01-01-00-00​ Tachometer, Dual Transducer Input, ±1 RPM Accuracy at 25 °C

Product Overview

The Bently Nevada 3300/50-01-01-00-00​ is a tachometer monitor from the classic 3300 Series machinery protection platform, now manufactured under the GE / Bently Nevada brand. Decoded against the factory option table, the catalog string is unusually specific: the leading 3300/50​ identifies the tachometer function, the first 01​ selects the dual-setpoint tachometer type, the second 01​ specifies an epoxy-sealed Alert relay, and the two trailing 00​ entries mean no agency approval and no internal safety barrier. In plain terms, the 3300/50-01-01-00-00​ is the workhorse speed-and-acceleration monitor for a standard, non-hazardous-area 3300 rack where the plant wants a local alert contact rather than a hermetic relay or a barrierized installation.

What the module actually does is deceptively simple and exactly what a rotating-machine train needs. It continuously derives shaft rotative speed, rotor acceleration or deceleration, and a zero-speed status from pulse-type transducers, then makes those values available three ways: as a user-proportional voltage or current output on the rear terminal strip, as Alert-status relay contacts for an external annunciator or PLC input, and as buffered raw transducer signals on two front-panel coaxial connectors. The speed range runs from 1 to 99,999 rpm, acceleration from –9,999 to +9,999 rpm/min, and the zero-speed state is declared below 100 rpm. Accuracy at the reference temperature is within ±1 rpm on speed and ±20 rpm/min on acceleration, which is more than fine enough for a turbine roll-up curve, a compressor surge investigation or a pump-coast-down study.

The architectural detail that separates the 3300/50-01-01-00-00​ from a generic panel tach is the dual-input voting. Although it is a single-channel monitor, it accepts two transducers — any mix of 3300, 7200 or 3000 series Proximitor inputs or a magnetic pickup — and runs the signals through internal voting logic. If one probe gaps out, cables, or is knocked loose during a turnaround, the monitor does not quietly invent a speed; the bad channel is detected and the indication is held or failed safe, so a single sensor fault cannot masquerade as a machine event. The two front-panel coax buffers are short-circuit protected and let a portable analyzer or a keyphasor input see the untouched pulse train without loading the monitor. For a site extending the life of a proven 3300 rack, the 3300/50-01-01-00-00​ is the correct, no-rewrite way to keep shaft-speed visibility and alarm annunciation exactly where the original design put them.

Technical Specifications