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.

Features

• 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

Spec Sheets

• Bently Nevada 990 Vibration Transmitter Data Sheet PDF (1.2 MB)

Links

• All possible part numbers

• The Bently Nevada 990 is a remarkable vibration transmitter designed for various industrial applications. Here is a detailed account:

• General Introduction

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• The Bently Nevada 990 is a 2-wire, loop-powered vibration transmitter156. It is mainly used for original equipment manufacturers (OEMs) of centrifugal air compressors, small pumps, motors, or fans135. It provides a 4 - 20 mA signal that is proportional to the relative vibration, serving as a simple and effective input for machinery control systems135.

• Technical Features

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• Input and Probe Compatibility: It accepts input from Bently Nevada's 3300 NSV proximity probes and matching extension cables in 5 m and 7 m system length options156.
• Signal Conditioning: The transmitter conditions the signal into appropriate peak-to-peak vibration amplitude engineering units1.
• Electrical Characteristics: It requires a +12 to +35 VDC input at the transmitter terminal1. The loop accuracy is within ±1.5% over the specified full-scale range1.
• Output Options: Besides the 4 - 20 mA output, it has non-isolated "PROX OUT" and "COM" terminals along with a coaxial connector, providing a dynamic vibration and gap voltage signal output for diagnostics15.
• Protection Circuits: It is equipped with a power-up inhibit circuit to eliminate signal errors caused by line voltage transients and a not ok/signal defeat circuit to prevent high outputs or false alarms from a faulty proximity probe or loose connection15.
• Mounting Options: It offers choices of DIN-rail clips or bulkhead mounting screws, which simplifies the mounting process15.
• Environmental Adaptability: With a potted construction, it can work well in high humidity environments of up to 100% condensing15.

• Performance Capabilities

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• Frequency Response: The frequency response ranges from 5 Hz to 6,000 Hz +0, -3 dB, enabling it to accurately capture a wide range of vibration frequencies16.
• Probe Gap: The probe must be gapped between 0.5 and 1.75 mm from the target to ensure the full-scale range1.

• Applications

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• The Bently Nevada 990 is widely used in multiple industries2. In the compressed air sector, it monitors the vibration of centrifugal air compressors. In the oil, gas and petrochemical industry, it is applied to small pumps and motors to detect potential faults. It is also utilized in waste-water and grey water treatment facilities for equipment vibration monitoring. In general, it is an essential device for machinery health monitoring and preventative maintenance.
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• In conclusion, the Bently Nevada 990 vibration transmitter, with its advanced features, reliable performance and wide range of applications, plays a vital role in ensuring the safe and efficient operation of various industrial machinery.