Bently Nevada 990-05-50-02-01 Vibration Transmitter

Description

The 990-05-50-02-01 provides continuous, proportional linear scaling of proximity probe signals into a simplified two-wire loop architecture. Engineered to serve industrial plant operators looking to streamline monitoring on high-speed assets, this compact component interfaces directly with standard machinery control infrastructure where basic alarm limits and process monitoring calculations are performed. By translating physical shaft movement into a standard analog format, it bridges the gap between field-level eddy current measurements and plant-wide control loops.

Constructed using a ruggedized, fully encapsulated potting compound, the unit functions safely when exposed to severe moisture, shifting temperatures, and airborne industrial contaminants. The system operates out of a single combined module housing, removing traditional multi-component panel steps and lowering the total hardware footings required inside remote field enclosures.

Features

• Combined Signal Processing Housing: Houses the proximity measurement electronics and transmitter circuitry inside a unified enclosure to reduce total component counts.
• Raw Signal Accessibility: Provides unfiltered dynamic diagnostic measurements through a dedicated high-frequency coaxial port without altering the primary loop output.
• Front-Panel Leveling Potentiometers: Contains uncoupled, non-interacting zero and span trimpots situated safely beneath the environmental overlay label for straightforward device loop adjustments.
• Loop Output Injection Test Pin: Includes an integrated verification path that allows external frequency signals to validate internal circuit operation and loop tracking.
• Automatic Alarm Suppression Logic: Uses an intelligent Not OK fault verification system to swiftly drop loop current below 3.6 mA, ensuring field wiring degradation or probe breaks do not induce false trips.
• High-Humidity Environmental Sealing: Features specialized internal potting that permits full 100% condensing humidity operation without degradation.
• Integrated Bulkhead Hardware Integration: Comes factory-configured with rugged mounting bolts optimized for direct plate attachment.

Applications

• High-speed centrifugal air compressors
• Compact industrial process pumps
• Medium and small electric induction motors
• Industrial ventilation fans and exhaust blower systems
• Asset-level plant-wide vibration trending networks

Ordering Information

Technical Specifications

Connections/Interfaces

Installation Guidelines

• Cable Selection Requirements: Run twisted-pair, shielded 1.0 mm2 (18 AWG) conductors for the primary 4 to 20 mA loop runs. The total length of this field loop wiring path can extend up to a maximum distance of 13 km (8 miles).
• Loop Voltage Calculations: Verify field loop resistances do not violate the linear operational boundary formula: RLOOP = 43.5 x (Vps - 12). If total resistance exceeds this computed maximum, the transmitter cannot reach full-scale 20 mA transmission.
• Diagnostic Port Phase Orientation: Note that the dynamic voltage signal supplied at the PROX OUT coaxial port is 180 degrees inverted relative to standard Bently Nevada instrumentation systems.
• Ground Loop Protection: Do not interface standard mains-powered or non-isolated AC diagnostic instruments directly to the raw PROX OUT ports. Use the 122115-01 Test Adapter to introduce necessary isolation and maintain plant safety integrity.
• Thread Coupling Restrictions: Ensure mechanical probe casings do not cross the absolute thread engagement maximum profiles (12 mm for M8x1 and 15 mm for M10x1) to eliminate permanent thread binding risks.

Compliance and Certifications

• FCC Rules Enforcement: Verified under Part 15 of standard FCC interference regulations
• Industrial EMC Performance: Certified to EN 61000-6-2, EN 61000-6-4, and the general EMC Directive 2014/30/EU
• Explosive Atmosphere Directives: Compliant with ATEX Directive 2014/34/EU and RoHS Directive 2011/65/EU
• Environmental Lifecycle Compliance: China RoHS 15-Year Environment Friendly Use Period (EFUP) specification under SJ/T 11364-2024
• Marine Type Approvals: Certified under ABS 2009 Steel Vessels Rules criteria
• North American Safety Marking: cNRTLus certified for Class I, Division 2, Groups A, B, C, and D hazardous fields (T5 @ Ta = +85 degC, Type 4 rating)
• International ATEX/IECEx Classification:
  • II 1 G Ex ia IIC T4 Ga (T4 rating with Ta operational window of -30 degC to +85 degC)
  • II 3 G Ex ec IIC T4 Gc (T4 rating with Ta operational window of -30 degC to +85 degC)

FAQ

What is the practical consequence of exceeding the maximum calculated loop resistance?

When the circuit resistance exceeds the limit defined by the supply voltage formula, the system runs out of electrical headroom. As a result, the loop current becomes clamped and fails to reach the 20 mA full-scale limit during high vibration events.

Why does the analog loop current read under 3.6 mA immediately after applying power?

This is an automated power-up inhibit cycle that runs for 2 to 3 seconds. It holds the transmitter in a Not OK state to let internal circuits stabilize, preventing initial electrical switch-on spikes from being misread as vibration trips.

How does the integrated signal defeat logic handle a broken extension cable?

The transmitter recognizes the open circuit as a Not OK condition and immediately drops the analog loop current below 3.6 mA within 100 microseconds. This rapid drop alerts the attached PLC or DCS that the measurement channel has failed rather than reporting an actual machine over-vibration event.

Can standard diagnostic instruments be hooked directly up to the BNC terminal?

Only battery-powered or fully floating diagnostic instruments should be attached to the non-isolated PROX OUT port. Grounded, AC-powered instruments require the 122115-01 signal isolation adapter to prevent ground loops that could trigger false alarms on the loop network.