990 Vibration Transmitter — Description (Refined Version)

The 990 Vibration Transmitter is designed primarily for original equipment manufacturers (OEMs) of centrifugal air compressors, small pumps, motors, and fans who require a simple, industry-standard 4–20 mA vibration signal as the input to their machinery control or monitoring system.

This two-wire, loop-powered transmitter is compatible with the 3300 NSv proximity probe and matching extension cable (available in 5 m and 7 m system lengths). The unit conditions the raw proximity probe signal and converts it into a proportional peak-to-peak vibration amplitude output. The resulting 4–20 mA signal can then be fed directly to the plant’s control system, where all machinery protection logic and alarm processing are performed.†

Key Features

Integrated Proximitor® Sensor
Eliminates the need for an external signal-conditioning module.

Dynamic Signal Outputs
Provides non-isolated PROX OUT and COM terminals, plus a coaxial connector for access to raw dynamic vibration and DC gap voltage signals for detailed diagnostics.‡

Independent Zero and Span Adjustment
Two non-interactive potentiometers, accessible beneath the transmitter label, support precise loop calibration.

Test Input Capability
A dedicated Test Input pin allows quick verification of the transmitter’s output using an external function generator.

Not OK / Signal Defeat Function
Prevents false alarms and abnormal high outputs caused by probe faults, wiring issues, or poor connections.

Flexible Mounting Options
Standard choices include DIN-rail mounting clips or bulkhead screw mounts to simplify installation in various environments.