Brand: Bently Nevada

Bently Nevada 991-06-50-01-01 Thrust Transmitter

Name: Bently Nevada 991-06-50-01-01 Thrust Transmitter – Datasheet
Brand: Bently Nevada

Description

Overview

The Bently Nevada 991-06-50-01-01 thrust transmitter is a 2-wire, loop-powered 991 Thrust Transmitter intended mainly for OEMs of centrifugal air compressors and small pumps, motors or fans that want a simple 4 to 20 mA axial displacement (thrust) signal as the input to their machine control system. It accepts a 3300 NSv proximity probe and matching extension cable (ordered separately) and outputs a signal proportional to the shaft axial position.

In the 991-AA-BB-CC-DD order code, this unit is configured for a 0.6-0-0.6 mm full-scale range, a 5.0 m system length, 35 mm DIN-rail clip mounting and CSA Division 2 approval. Probe gap and range adjustment are critical in thrust measurement and must follow the manual.

Key Features

Integrated Proximitor Sensor; no external signal conditioner required
4 to 20 mA output proportional to axial position over a 0.6-0-0.6 mm range
Non-isolated PROX OUT terminals and coaxial connector for diagnostics
Non-interacting zero and span adjustments and a Test Input pin
Not OK / signal defeat and power-up inhibit circuits
Potted construction for up to 100% condensing humidity

Technical Specifications

Parameter	Value
Part number	991-06-50-01-01
Full-scale option	06: 0.6-0-0.6 mm
System length option	50: 5.0 m
Mounting option	01: 35 mm DIN-rail clips
Agency approval option	01: CSA Division 2
Input	One 3300 NSv proximity probe and extension cable
Power	+12 to +35 Vdc at transmitter terminals
Output	4 to 20 mA over full-scale range, 2-wire loop
Loop accuracy	±1.5% over full-scale range
Max. loop resistance	1,000 Ω including cable at 35 Vdc
Current limiting	23 mA typical
Not OK / signal defeat	Output <3.6 mA within 100 µs of Not OK
Prox Out linear range	0.25 to 1.65 mm (10 to 65 mils)
Prox Out scale factor	7.87 mV/µm (200 mV/mil) ±6.5% typical
Minimum target	9.5 mm diameter
Transmitter operating temperature	-35 °C to +85 °C
Transmitter weight	0.43 kg
Transmitter storage temperature	-51 to +100 °C
Recovery after Not OK	Output restored within 0.1 s after the fault clears
Prox Out output impedance	10 kΩ, calibrated for a 10 MΩ load
Scale factor temperature stability	Within ±10 % of 7.87 mV/µm from 0 to +70 °C
Maximum Prox Out (BNC) lead length	3 m
Maximum loop cable length	13 km with 1.0 mm² (18 AWG) shielded twisted pair
Maximum loop resistance versus supply	43.5 × (supply voltage – 12) Ω
Hazardous area rating in datasheet	Class I, Division 2, Groups A-D, T4, -30 to +85 °C ambient
Supply limit in Zone 2 / Division 2	28 V
Probe temperature range	-52 to +177 °C operating and storage
Total system weight	0.82 kg typical

Applications

Rotor axial (thrust) position trending and alarming on packaged centrifugal air compressors
Small pumps, motors and fans where a PLC or DCS reads a 4 to 20 mA thrust value
Division 2 classified areas in oil & gas and petrochemical facilities

Bently Nevada 991-06-50-01-01 Ordering Code and Options

The 991 code is 991-AA-BB-CC-DD. AA is the full-scale range and only two exist: 06 for 0.6-0-0.6 mm and 25 for 25-0-25 mils. Both are bidirectional ranges centred on zero, so the output moves either side of mid-scale as the rotor shifts in the normal or counter direction. BB is the system length, 50 for 5.0 m or 70 for 7.0 m. CC is the mounting, with 01 for 35 mm DIN-rail clips, 02 for bulkhead screws and 03 for both. DD is the agency approval: 00 none, 01 CSA Division 2, and 05 CSA Division 2 with ATEX Zone 0 and Zone 2 plus ABS maritime approval.

This part number is therefore a metric-range, 5.0 m, DIN-rail transmitter with CSA Division 2 approval. Users who need ATEX or IECEx marking should look at the -05 version instead. The transmitter uses the same 3300 NSv probes and 330930 extension cables as the 990 vibration transmitter; for a 5.0 m system the listed extension cables are 4.0 m (330930-040) and 4.5 m (330930-045).

Bently Nevada 991-06-50-01-01 Installation and Wiring Notes

Probe gap setting is the critical step with a thrust transmitter. The manufacturer warns that an incorrect gap can stop the output reaching full scale in one or both directions, leaving the machine effectively unmonitored. The Test Input pin accepts a variable DC voltage source so the loop output can be checked without moving the probe.

PROX OUT is not isolated from the 4 to 20 mA loop and its polarity is inverted relative to a standard Proximitor. Grounded mains-powered test equipment should be connected only through Test Adapter 122115-01.

Why Seven Star LLC

Seven Star LLC supplies Bently Nevada (Baker Hughes) 991 series thrust transmitters to power, oil & gas, petrochemical and water customers across Oman and the GCC. Before quoting, we check the complete part number and the full-scale range, system length, mounting and approval options against the equipment already installed, so the replacement matches the existing system.

Request a Quote for Bently Nevada 991-06-50-01-01 Thrust Transmitter

Submit a formal inquiry through our RFQ page with the transmitter part number 991-06-50-01-01, the quantity, the required full-scale range and the installed 3300 NSv probe part number. We will confirm the correct configuration and respond with a formal quotation. | Inquiry Form

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About brand

Since 1961 Bently Nevada, of Minden, Nevada, USA, has been closely tied to two things: the eddy current proximity probe and the rack-based machinery protection system. The 3500 rack is found on turbines and compressors in most large process plants.

Seven Star LLC is an independent supplier of Bently Nevada 3500 monitor modules, interface and communication modules, proximity probes, accelerometers and velocity transducers for operators in Oman and the GCC, with every item matched to the full part number.

Bently Nevada 3500 modules and transducers

The listed 3500 modules include the 3500/20 Rack Interface Module, the 3500/50M Tachometer, the 3500/61 Temperature and 3500/62 Process Variable monitors, the 3500/64M Dynamic Pressure monitor, the 3500/44M for aeroderivative gas turbines and the 3500/46M Hydro monitor. Reciprocating compressor monitoring is covered by the 3500/70M, 3500/72M and 3500/77M. The 3500/92 Communication Gateway and 3500/94M display link the rack to the control system. Transducers include the 3300 XL proximity probe system, the 330400 accelerometer and the 190501 Velomitor CT velocity transducer. The manufacturer's newer platform, Orbit 60, is offered as the modernization path for 3500 racks, and System 1 software handles diagnostics.

Where Bently Nevada vibration monitoring is used

Steam and gas turbines, generators, centrifugal and reciprocating compressors, large pumps, hydro units and cooling tower fans in oil and gas, power generation, petrochemical and mining plants are the usual machines. Measurements include radial vibration, thrust position, speed, phase, differential expansion, bearing temperature, rod position and cylinder pressure.

Ordering Bently Nevada parts: what we need

Send the complete part number with every option field, for example 330103-00-05-10-01-00 for a probe or the 3500 module number with its option dashes, plus the matching I/O module number. For probe systems state probe series, system length and the hazardous area approval. A photo of the label avoids transcription errors, and for rack modules the firmware revision is useful.

Browse Bently Nevada products by category: Vibration.