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Overview
The 990-05-70-03-05 belongs to the Bently Nevada 990 series, a line of two-wire vibration transmitters. Engineers deploy this unit to monitor shaft vibration continuously on turbines, compressors, and pumps. Consequently, it delivers a 4–20 mA output proportional to vibration velocity, enabling direct integration with DCS and PLC systems.
Key Technical Specifications
The 990-05-70-03-05 integrates a proximity probe driver and signal conditioner in one housing. Moreover, it supports API 670 machinery protection requirements. Below are the core parameters.
| Parameter | Specification |
|---|---|
| Product Type | Two-wire vibration transmitter |
| Series | Bently Nevada 990 |
| Full-Scale Range | 0–25 mm/s (0–1.0 in/s) RMS |
| Output Signal | 4–20 mA, loop-powered |
| Frequency Response | 4 Hz to 1,000 Hz |
| Supply Voltage | 12–35 VDC |
| Operating Temperature | –35 °C to +85 °C |
| Storage Temperature | –40 °C to +100 °C |
| Humidity | 0–95%, non-condensing |
| Housing Material | 316 stainless steel |
| Weight | Approximately 0.45 kg (1.0 lb) |
| Dimensions | 25 mm diameter × 105 mm length |
| Mounting Thread | 3/8-24 UNF |
| Connector Type | 3-pin MIL-style circular |
| Cable Length (std.) | 5 meters |
| Compliance | API 670, CE, ATEX optional |
Installation and Interface Details
Mounting the 990-05-70-03-05 requires a standard 3/8-24 UNF threaded hole. The unit then connects through a 3-pin MIL-style connector. Furthermore, the two-wire loop simplifies wiring significantly, because power and signal share one pair. As a result, installation costs drop compared with four-wire systems.
Signal Conditioning and Output
Internally, the transmitter converts eddy-current probe signals into a conditioned 4–20 mA output. The frequency response spans 4 Hz to 1,000 Hz, which covers most rotating machinery applications. Additionally, the loop-powered design draws less than 25 mA, so it suits hazardous-area installations when paired with proper barriers.
Environmental and Mechanical Ratings
The 316 stainless steel housing resists corrosion in harsh plant environments. It operates reliably from –35 °C to +85 °C. Meanwhile, the sealed construction tolerates 0–95% relative humidity without condensation issues. Consequently, the device performs well in steam turbine rooms and offshore platforms.
Why Engineers Choose This Transmitter
This transmitter offers several practical advantages. First, it combines probe driving and signal conversion in a single unit. Second, it meets API 670 requirements for vibration monitoring. Third, its compact size fits tight mounting locations. Therefore, maintenance teams reduce spare-part inventory and wiring complexity.