Bently Nevada 990-04-50-01-05 Vibration Transmitter
Product Introduction
The Bently Nevada 990-04-50-01-05 belongs to the 990 series of vibration transmitters. It works with one non-contacting 3300 NSv proximity probe and an extension cable. This device converts radial vibration measurements into a standard 4-20 mA signal.
Many offshore and hazardous area facilities rely on this 990-04-50-01-05. The full-scale option is set to 0-4 mils pp (0-100 μm pp). Additionally, the system length reaches 5.0 meters (16.4 feet), which provides flexibility during panel installation.
Technical Specifications
Power and Output
The transmitter requires +12 to +35 Vdc at its terminal. It operates in a two-wire loop-powered configuration. Maximum loop resistance equals 1,000 Ω including cable at 35 Vdc. Typical current limiting sits at 23 mA.
4-20 mA Loop Accuracy
Accuracy stays within ±1.5% over the specified full-scale range. Bently Nevada rates this accuracy from the TEST signal input to the voltage measured across a 250 Ω loop resistance. Note that the ±1.5% error adds to the Prox Out Incremental Scale Factor.
Frequency Response
The frequency response ranges from 5 Hz to 6,000 Hz (+0, -3 dB). This wide bandwidth captures common vibration frequencies in turbines, compressors, and pumps.
Probe Gap Requirement
You must gap the probe between 0.5 and 1.75 mm (20 and 55 mils) from the target. This ensures the full-scale range performs correctly.
Not OK / Signal Defeat
When a Not OK condition appears, the output drops below 3.6 mA within 100 µs. After the Not OK condition clears, the signal restores within 2-3 seconds.
Hazardous Area Approvals
This model carries agency approval option 05, which includes multiple certifications. It suits nonhazardous, Zone 2, or Division 2 locations. More importantly, it also holds ATEX Zone 0 approval for the most demanding explosive atmospheres. Additionally, the ABS maritime approval makes it suitable for shipboard and offshore applications. The power supply should be 28 V for hazardous area installations.
Environmental and Mechanical Limits
Transmitter Temperature
Mounting and Weight
The unit mounts on a 35 mm DIN rail using option 01 35 mm DIN rail clips. Total weight is 0.43 kg (0.9 lbm).
Minimum Target Size
The minimum target diameter is 9.5 mm (0.375 inches).
Frequently Asked Questions (FAQ)
1. What makes the 990-04-50-01-05 different from the 990-04-50-03-01?
The main difference lies in approvals and mounting. The 990-04-50-01-05 includes ATEX Zone 0 and ABS maritime approval, plus 35 mm DIN rail clips. The 03-01 version has CSA Division 2 only and uses DIN clips with screws.
2. Can I use this transmitter in a Zone 0 gas environment?
Yes. The Bently Nevada 990-04-50-01-05 holds ATEX Zone 0 approval. You must still follow proper installation practices and use appropriate barriers.
3. Is the ABS approval required for all marine installations?
For shipboard and offshore platforms, many classification societies require ABS or equivalent approval. This model meets that requirement directly.
4. How does the frequency response start at 5 Hz?
The lower cutoff at 5 Hz removes very low frequency motion. This design focuses on machine vibration rather than slow shaft movement or thermal expansion.
5. What happens if I exceed the 3-meter leadwire length?
Signal degradation may occur beyond 3 meters for the Proximitor Sensor Output. Keep the cable length within the specified limit to maintain accuracy.
