The Bently Nevada 991 Thrust Transmitter provides a 4-20 mA signal proportional to thrust position and is designed for use on smaller, non-critical machinery. Its primary use is on centrifugal air compressors with fluid-film thrust bearings. The 991 Thrust Transmitter can measure up to 1.2 mm or 50 mils of total thrust movement.
The 991 thrust transmitter is a 2-wire, loop-powered device that accepts input from Bently Nevada's 3300 NSv proximity probes and matching extension cables (available in 5 and 7 meter system length options). The transmitter conditions the signal into appropriate engineering units proportional to the shaft's axial position, and provides it as a 4 to 20 mA industry-standard signal for input to the control system where machinery protection alarming and logic occurs.
|Bently Nevada 991 Thrust Transmitter Specifications|
|Input||Accepts 1 non-contacting 3300 NSv Proximity Probe and extension cable|
|Power||Requires +12 to +35 Vdc input at the transmitter terminal|
|Signal Output||4 to 20 mAdc over specified full-scale range in 2-wire configuration|
|Loop Accuracy||Within ±1.5% over specified full-scale range|
|Maximum Loop Resistance||1,000 Ω including cable at 35 Vdc|
|Current Limiting||23 mA typical|
|Zero and Span||Non-interacting external adjustments|
|NOT OK/Signal Defeat||Signal output will go to less than 3.6 mA within 100 μs after a Not OK condition occurs. Signal output is restored within 0.1 seconds after the Not OK condition is removed|
|Proximitor Sensor Output||Compatible with ungrounded, portable test equipment. When using grounded, ac-powered test equipment, use the 122115-01 Test Adapter for signal isolation|
|Output Impedance||Prox Out has a 10 kΩ output impedance calibrated for a 10 MΩ load|
|Linear Range||0.25 to 1.65 mm for Prox Out. Suitable for 0.6-0-0.6 mm or 25-0-25 mils current loop linear ranges|
|Prox Out Incremental Scale Factor||7.87 mV/μm (200 mV/mil) ± 6.5% typical including interchangeability errors when measured in increments of 0.25 mm over the linear range using a flat 30 mm target|
|Temperature Stability||Incremental scale factor remains within ±10% of 7.87 mV/μm from 0 °C to +70 °C|
|Minimum Target Size||9.5 mm diameter|
|Leadwire Length||Maximum for Proximitor Sensor Output (BNC connector), maximum cable distance is 3 meters|
|Non-Hazardous, Zone 2 or Div 2 Hazardous area locations||13 km (8 miles) maximum between transmitter and receiving device for signal output|
|Intrinsically Safe Hazardous area locations||68 meters (225 ft.) maximum between transmitter and receiving device for signal output|
|Electrical Classification||General Purpose Approval by Canadian Standards Association (CSA/NRTL/C) in North America and by VDE in Europe. The 991 has the CE mark for Europe|
Please consider these optional accessories.
This product can be used in the following applications:
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