Description
The 990 Vibration Transmitter is intended primarily for the original equipment manufacturers (OEMs) of centrifugal air compressors or small pumps, motors, or fans who prefer to provide a simple 4 to 20 mA proportional vibration signal as the input to their machinery control system.
The transmitter is a two-wire, loop-powered device that accepts input from our 3300 Nsv proximity probe and its matching extension cable (available in 5m and 7m system length options)
The transmitter conditions the signal into appropriate peak-to-peak vibration amplitude engineering units, and provides this value as a proportional 4 to 20 mA industry-standard signal as the input to the control system where machinery protection alarming and logic occurst.
The 990 transmitter provides the following notable features:
- Integrated Proximitor Sensor requires no external unit
- Non-isolated “PROX OuT and “COM terminals plus a coaxial connector to provide a dynamic vibration and gap voltage signal output for diagnostics.
- Non-interacting zero and span potentiometers under the Transmitter label supports loop adjustment.
- Test input pin for quick verification of loop signal output, using a function generator as the input.
- A Not OK/signal Defeat circuit prevents high outputs or false alarms due to a faulty proximity probe or loose connection.
- Choice of DlN-rail clips or bulkhead mounting screws as standard options simplifies mounting.
- Potted construction for high humidity (upto 100% condensing)environments. Compatibility with 3300 Nsv proximity probe alows transducer installation in small areas with minial clearance, typical of centrifuqal air compressors.
Notes
Vibration transmitters have many limitations when compared to a continuous vibration
monitoring system. They are a practical solution in some applications for measuring general vibration levels and are a valuable tool for overall vibration trending. However, they provide limited capability for machinery diagnostics using the vibration signal and do not capture dynamic vibration signals (used for diagnostics) in the event of a vibration alarm. While the transmitter is capable of peak vibration alarming and non-OK checking, the 4-20 mA signal cannot be used to determine the phase of vibration, and monitor functions such as gap alarms, phase alarms, Timed OK channel defeat, Danger Bypass, and Trip Multiply cannot be used. In addition, PLCs attached to the vibration transmitter can only provide peak-to-peak trending data and are not suitable for plant-wide diagnostic systems such as System 1 or Rule Paks.
The 990 Vibration Transmitter’s “Prox Out” coaxial connector provides a non-isolated dynamic transducer signal for machinery diagnostics. You can connect this signal directly to battery-powered or isolated test equipment to diagnose machinery problems. However, since the “PROX OUT” signal is not isolated from the 4 to 20mA loop signal, an interface is available (and strongly recommended) for signal isolation. The 990/991 Test Adapter conditions the 990 Transmitter’s “PROX OUT” signal for use with ac-powered test equipment. It also inverts and isolates the 990′s transducer signal, making it suitable for equipment such as oscilloscopes and analyzers, and presering industry standard conventions for signal polarity. We strongly recommend the use of this test adapter for all applications to maintain isolation between test equipment and the loop signal, and ensure that the installation maintains machinery protection integrity.
Stock part list:
990-04-50-01-00
990-05-50-01-00
990-05-XX-01-00 MOD: 165335-01
990-10-XX-01-05 MOD 165353-07
990-08-XX-01-01 MOD 165335-1
Post time: Sep-23-2025