Bently Nevada 990-05-50-01-01 990 Series Vibration Transmitter

Description

The 990-05-50-01-01 is a two-wire, loop-powered vibration transmitter designed primarily for original equipment manufacturers (OEMs) of centrifugal air compressors, small pumps, motors, or fans. This device accepts an input signal from a non-contacting 3300 NSv proximity probe and its matching extension cable. It conditions the incoming transducer signal into appropriate peak-to-peak vibration amplitude engineering units and provides a proportional 4 to 20 mA industry-standard output signal directly to a machinery control system where alarm logic and protection processes occur.

Equipped with an integrated Proximitor sensor, the 990-05-50-01-01 eliminates the requirement for an external standalone proximitor unit, reducing cabinet footprint. The encapsulated potted construction makes it highly reliable in harsh, high-humidity environments. For auxiliary diagnostic purposes, the unit includes non-isolated PROX OUT and COM terminals along with a coaxial connector to supply dynamic vibration data and gap voltage outputs.

Features

• Integrated Proximitor Sensor: Combines the electronics within the transmitter casing, requiring no additional separate processing units.
• Dynamic Diagnostic Outputs: Features non-isolated PROX OUT and COM terminals alongside a coaxial connector to deliver unfiltered dynamic vibration and gap voltage measurements.
• Streamlined Calibration: Includes non-interacting zero and span potentiometers beneath the primary label to support effortless field loop adjustment.
• Quick Loop Verification: Integrates a Test Input pin allowing rapid validation of loop signal outputs via a function generator.
• Not OK / Signal Defeat Circuitry: Intercepts faulty inputs from loose connections or damaged proximity probes to immediately suppress false alarms by dropping the loop signal below 3.6 mA.
• Potted Casing Construction: Optimized for high-humidity deployment up to 100% condensing environments.
• Versatile Mounting Hardware: Supports standard choice of 35 mm DIN-rail clips or bulkhead mounting configurations.

Applications

• Centrifugal air compressors
• Industrial small pumps
• Electric motors
• Cooling and ventilation fans
• Rotating machinery overall vibration trending

Ordering Information

Technical Specifications

Connections/Interfaces

Installation Guidelines

• Wiring Specifications: Use standard 2-conductor, twisted, shielded 1.0 mm2 (18 AWG) cable (part number 02173006) for loop wiring and terminal-strip PROX OUT runs. Maximum acceptable loop wire path length is 13 km (8 miles).
• Loop Resistance Restrictions: Ensure that the total loop resistance satisfies the mechanical formulation: RLOOP = 43.5 x (Vps - 12) ohms. Exceeding the maximum resistance region limits full-scale current outputs below 20 mA.
• PROX OUT Phasing & Isolation: The phase of the PROX OUT raw diagnostic output signal is natively inverted compared to standard Bently Nevada outputs. Never directly connect grounded AC-powered diagnostic gear to the PROX OUT port to protect against false trip conditions. Use the specialized 122115-01 Test Adapter to introduce necessary dynamic voltage inversion and signal isolation.
• Enclosure Grounding and Shielding: Terminate cable shields safely at the instrumentation common end to mitigate severe EMI/RFI noise pickup. Verify probe coaxial cables are protected from industrial moisture intrusion via connector protectors or fluorosilicone boots.
• Thread Engagement Boundaries: Strictly respect nominal installation torque and maximum thread engagement lengths (12 mm for M8x1, 15 mm for M10x1) to avoid mechanical binding or physical housing failures.

Compliance and Certifications

• FCC: Complies with Part 15 of FCC Rules
• EMC Directives: EN 61000-6-2, EN 61000-6-4, EMC Directive 2014/30/EU
• ATEX Directive: 2014/34/EU
• RoHS: RoHS Directive 2011/65/EU, China RoHS 15-year EFUP (SJ/T 11364-2024)
• Maritime: ABS 2009 Steel Vessels Rules
• North American Approvals: cNRTLus Class I, Division 2, Groups A, B, C, D (T5 @ Ta = +85 degC, Type 4)
• Hazardous Area ATEX/IECEx Ratings:
  • II 1 G Ex ia IIC T4 Ga (T4 @ Ta = -30 degC to +85 degC)
  • II 3 G Ex ec IIC T4 Gc (T4 @ Ta = -30 degC to +85 degC)

FAQ

What is the function of the Not OK/Signal Defeat circuit on the transmitter?

The circuit detects internal or environmental faults such as broken proximity probe hardware or unsecured cable interfaces. When an issue occurs, it rapidly forces the loop output current down to less than 3.6 mA within 100 microseconds, suppressing downstream false protection triggers.

Can a standard oscilloscope be attached directly to the coaxial output plug?

Directly connecting mains-powered, grounded AC diagnostic test gear to the raw PROX OUT BNC or terminal strip can create ground loops and generate false alarms. For safe dynamic diagnostic analysis, a 122115-01 Test Adapter is required to correctly invert and isolate the signal.

What power supply range is required for standard 2-wire loop operation?

The device operates on a 2-wire transmitter network and requires a DC supply voltage input between +12 Vdc and +35 Vdc measured right across the terminal blocks.

How does the power-up inhibit feature behave during system startup sequences?

Upon receiving loop power, the device forces its output signal to drop below 3.6 mA for a duration of 2 to 3 seconds. This initialization delay keeps the machinery control logic from confusing startup power transients with valid over-vibration signals.