The 990-05-70-02-00 is a precision industrial-grade, two-wire, loop-powered vibration transmitter. It is specifically designed to convert mechanical vibration displacement into a standard 4-20 mA current signal for direct input into control systems such as PLCs or DCSs.
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
The 990 Vibration Transmitter is used for centrifugal air compressors, small pumps, motors, or fans to provide a 4 to 20 mA proportional vibration signal as the input to a machinery control system. The transmitter is a two-wire, loop-powered device that accepts input from a 3300 NSv proximity probe and its matching extension cable in 5-meter or 7-meter system length options.
The transmitter conditions the raw transducer signal into peak-to-peak vibration amplitude engineering units. It provides this value as a proportional 4 to 20 mA industry-standard signal to the control system where machinery protection alarming and logic occurs. This device operates as a utility for measuring general vibration levels and overall vibration trending.
The transmitter provides limited functions for machinery diagnostics using the vibration signal and does not capture dynamic vibration signals in the event of a vibration alarm. While the transmitter executes peak vibration alarming and non-OK checking, the 4 to 20 mA signal does not determine the phase of vibration. Monitor functions including gap alarms, phase alarms, Timed OK channel defeat, Danger Bypass, and Trip Multiply are not available. Programmable Logic Controllers (PLCs) attached to the vibration transmitter receive peak-to-peak trending data and do not interface with plant-wide diagnostic networks such as System 1 or Rule Paks.
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description.
Bently Nevada 990-05-70-02-00 Vibration Transmitter Manuals, Datasheets, Drivers, Link
Important Notice: Other accessories, manuals, cables, calibration data, software, etc. are not included with this equipment unless listed in the above stock item description.
Petroleum Refining
Deployed on the fluid-film bearing housings of auxiliary high-pressure oil pumps or water injection pumps around crude distillation towers and hydrocracking units; its potted construction for high humidity withstands up to 100% condensing environments to output continuous vibration amplitudes for basic trend logging.
Thermal Power Generation
Installed on the fluid-film bearings of boiler induced draft fans, forced draft fans, or steam turbine auxiliary lubricating oil pumps; since it lacks hazardous area approvals, it is typically deployed on small-to-medium rotating trains within safe areas to provide simple vibration measurement and control for the plant DCS.
Iron and Steel Smelting
Deployed on the bearing housings of blast furnace blower auxiliary thin-oil stations and hoist drive units, utilizing the long-distance, high-immunity transmission characteristics of its 2-wire current loop to prevent data distortion from strong high-frequency electromagnetic interference caused by large on-site motors.
Coal Chemical Industry
Used on fluid-film bearings of small-to-medium centrifugal refrigeration compressors or process auxiliary centrifugal pumps, utilizing the PROX OUT dynamic output port on its faceplate paired with a dedicated 990/991 test adapter, it allows technicians to easily connect oscilloscopes online to diagnose shaft orbit faults.
Hydropower Industry
Used on oil-water separation pumps and high-pressure jack oil pumps of small-to-medium bulb hydro-generator units; the non-contact 3300 NSv probe penetrates fluid films to convert micron-level relative motions into standard 4 to 20 mA current feedback for the plant-wide monitoring main line.
The 990-05-70-02-00 is a 2-wire loop-powered device requiring the external power supply to be strictly maintained within 12 to 35 VDC during field wiring, as a supply voltage more positive than 12 VDC will prevent full-scale 20 mA output.
This transmitter exclusively supports the 3300 NSv proximity probe and a 7-meter system length, must be securely fastened using bulkhead screws, and is strictly prohibited from exposure to flammable and explosive industrial sites without utilizing safety barriers or explosion-proof isolation measures.
Additionally, the dynamic signal from its front-panel PROX OUT port is not isolated from the 4-20 mA loop; when connecting external AC-powered calibration or analysis equipment on-site, a dedicated 990/991 test adapter must be used for signal isolation to prevent loop interference and guarantee the integrity of the machinery protection functions.
A two-wire, loop-powered vibration transmitter (0–5 mils range, 7.0m system length, panel mount, non-approved). It converts 3300 NSv probe signals into a standard 4–20 mA DC trend output for PLCs, and features a non-isolated PROX OUT connector for raw dynamic AC diagnostic signals.
It is a 990 series eddy current vibration transmitter manufactured by Bently Nevada. It converts non-contact displacement measurements from a machinery surface into a standard industrial current signal.
How does the 990-05-70-02-00 operate?
It emits a high-frequency radio electromagnetic field to the observed shaft surface via the connected probe. Shaft vibration alters the returned eddy current signal, and the transmitter's internal circuitry processes this signal into a 4 to 20 mA current output.
What specific vibration amplitude does the 4-20 mA output of the 990-05-70-02-00 correspond to?
The current signal has a linear relationship with the peak-to-peak vibration: 4 mA corresponds to 0 mils (no vibration), and 20 mA corresponds to its full-scale upper limit of 5 mils (125 micrometers).
What is the purpose of the PROX OUT interface on the 990-05-70-02-00?
The coaxial connector provides an unisolated, unconditioned raw dynamic vibration signal (AC voltage signal). It connects directly to portable data analyzers or oscilloscopes for machinery fault diagnostics by factory engineers.
Can the PROX OUT signal of the 990-05-70-02-00 connect directly to AC-powered test equipment?
Direct connection is not recommended. Because PROX OUT is not isolated from the 4-20 mA loop, connecting to AC-powered equipment can upset the loop balance or introduce noise. A 990/991 Test Adapter must be used for electrical isolation and signal inversion.
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