Description

Bently Nevada 990-05-70-02-00 | 990 Series Vibration Transmitter

The Bently Nevada 990-05-70-02-00 is a high-precision, loop-powered vibration transmitter designed to provide a 4-20 mA output signal directly proportional to radial vibration. This specialized device integrates the functions of a Proximitor sensor and a signal conditioner into a single, compact unit. It interfaces directly with standard 3300 NSv proximity probes and extension cables to monitor small centrifugal compressors, pumps, and motors. By converting complex eddy-current signals into a linear 4-20 mA current loop, the 990-05-70-02-00 enables users to connect machinery vibration data directly to Programmable Logic Controllers (PLCs) or Distributed Control Systems (DCS). This architecture eliminates the need for dedicated vibration monitoring racks, making it an ideal choice for localized protection of non-API-670 standard machinery.

Core Technical Characteristics and Functional Design

Engineered for harsh industrial environments, the 990-05-70-02-00 features a rugged housing that resists moisture and chemical exposure. The unit effectively manages signal processing to deliver real-time peak-to-peak vibration measurements. It provides a non-isolated 4-20 mA loop that remains stable even across temperature fluctuations and electromagnetic interference. Additionally, the transmitter includes a “Not OK” signal state, where the current drops below 3.6 mA if the probe or cable develops a fault. This proactive diagnostic feature ensures that control systems do not misinterpret a sensor failure as low vibration. Because the device utilizes a simple two-wire interface, technicians can reduce installation costs and simplify field wiring in both new and retrofit applications.

Technical Specifications

• Manufacturer: Bently Nevada (Baker Hughes)
• Model Number: 990-05-70-02-00
• Product Type: 4-20 mA Vibration Transmitter
• Full-Scale Range: 0 to 5 mils peak-to-peak (0-125 µm)
• System Compatibility: Works with 3300 NSv Proximity Transducer System
• Output Signal: 4-20 mA DC (Proportional to vibration)
• Supply Voltage: +12 to +35 Vdc
• Operating Temperature: -35 °C to +85 °C (-31 °F to +185 °F)
• Mounting Options: 35mm DIN rail or G-rail
• Weight: 0.44 kg (0.97 lbs)
• Dimensions: 7.4 cm x 4.6 cm x 10.0 cm
• Certification: Hazardous area approved (CSA, ATEX, IECEx)

Industrial Applications and Strategic Benefits

Maintenance teams in the oil and gas, manufacturing, and utility sectors deploy the 990-05-70-02-00 to safeguard secondary rotating assets. For instance, engineers often specify this transmitter for monitoring small gas expanders and high-speed centrifugal pumps where space is limited. By providing continuous data to the plant DCS, the transmitter empowers operators to implement predictive maintenance strategies, effectively reducing the risk of catastrophic mechanical failure. The 990-05-70-02-00 simplifies the path to digitalization by providing a standardized current output that any modern control system can interpret. Consequently, facilities achieve higher equipment reliability and lower total cost of ownership for their vibration protection programs.

Frequently Asked Questions

Does this transmitter require a separate Proximitor?

No, the 990-05-70-02-00 incorporates the Proximitor functionality internally. You connect the proximity probe extension cable directly to the transmitter terminals.

Can I use the 990-05-70-02-00 with a standard 8mm proximity probe?

No, this specific model requires the 3300 NSv (Non-Standard velocity) probe system, which Bently Nevada designed for applications with small targets or tight clearances.

What happens to the signal if the probe cable is cut?

The transmitter utilizes a “Not OK” diagnostic logic. If the system detects a cable break or a short circuit, the 4-20 mA output will drop below the standard 4 mA threshold (typically to 3.6 mA or less) to alert the control system of a hardware fault.

Is it necessary to use a signal isolator with this transmitter?

While not always required, using a signal isolator or a safety barrier is highly recommended when installing the transmitter in hazardous areas or when connecting to a PLC/DCS that does not have isolated inputs.