توضیحات
The Bently Nevada 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 990 vibration transmitter is a 2-wire, loop-powered device that accepts input from Bently Nevada’s 3300 NSv proximity probes and a matching extension cable (available in 5 m and 7 m 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 occurs.
| Bently Nevada 990 Vibration 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 | 4-20 mA |
| Loop Accuracy | Within ±1.5% over specified full-scale range |
| Probe Gap | Probe must be gapped between 0.5 and 1.75 mm from target to ensure 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 2-3 seconds after the Not OK condition is removed |
| Power-up Inhibit | Signal output stays at less than 3.6 mA for 2 to 3 seconds after power is applied |
| 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 |
| Prox Out Linear Range | 1.4 mm. Begins at approximately 0.25 mm from target surface |
| 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. Worst case 7.87 mV/μm ± 10%. Typical Noise Level: 50 mV/pp |
| Temperature Stability | Incremental scale factor remains within ±10% of 7.87 mV/μm from 0 °C to +70 °C |
| Frequency Response | 5 Hz to 6,000 Hz +0, -3 dB |
| Minimum Target Size | 9.5 mm diameter |
| Leadwire Length | Maximum for Proximitor Sensor Output (BNC connector), maximum cable distance is 3 meters |
| Electrical Classification | General Purpose Approval by Canadian Standards Association (CSA/NRTL/C) in North America and by VDE in Europe. 990 has the CE mark for Europe |
Features Bently Nevada 990
- 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 Power-up Inhibit circuit eliminates signal errors due to line voltage transients
- A Not OK/Signal Defeat circuit prevents high outputs or false alarms due to a faulty proximity probe or loose connection
- Choice of DIN-rail clips or bulkhead mounting screws as standard options simplifies mounting
- Potted construction for high humidity (up to 100% condensing) environments
- Compatibility with 3300 NSv proximity probe allows transducer installation in small areas with minimal clearance, typical of centrifugal air compressors
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