Brand: Bently Nevada

Bently Nevada 125792-01 3500 Keyphasor Module Board

Name: Bently Nevada 125792-01 3500 Keyphasor Module Board
Brand: Bently Nevada
SKU: 125792-01

Description

Bently Nevada 125792-01 3500 Keyphasor module board

The Bently Nevada 125792-01 is the earlier Keyphasor module printed-wiring assembly for the 3500 rack. The 3500/25 datasheet states that the 125792-01 is completely replaced by the updated 149369-01 Enhanced Keyphasor Module, which can be ordered as a direct plug-in replacement with the same form, fit and function.

Seven Star LLC supplies this board for operators with original racks who need to keep the earlier part, and can quote the 149369-01 as a replacement where an upgrade is preferred.

125792-01 technical specifications

Parameter	Specification
Manufacturer / part number	Bently Nevada 125792-01 (Keyphasor module PWA, superseded by 149369-01)
Channels	2 per half-height module (order 4 channels with two cards)
Inputs	Proximity probe transducers or magnetic pickups; range +0.8 V to -21.0 V (non-isolated I/O) or +5 V to -11 V (isolated I/O)
Input impedance	21.8 kΩ minimum
Speed range	1 to 1,200,000 cpm (0.017 to 20 kHz); output 1 to 99,999 cpm
Auto threshold	Minimum 2 V peak-to-peak and 120 rpm (2 Hz)
Manual threshold	0 to -20 Vdc, minimum 500 mV peak-to-peak; hysteresis 0.2 to 2.5 V
Accuracy, non-processed	±1 cpm to 100 Hz, ±8 cpm 101-500 Hz, ±1% above
Transducer power	-24 Vdc, 40 mA maximum per channel
Buffered outputs	Two on the front (coaxial) and two on the rear (Euro style), 504 Ω maximum
Power consumption	3.2 W typical
Main module	Half-height, 119.9 x 24.4 x 256.5 mm, 0.34 kg
I/O module	241.3 x 24.4 x 103.1 mm, 0.46 kg, 1 full-height rear slot
Operating temperature	-30°C to +65°C; 0°C to +65°C for internal-barrier I/O with internal terminations
Storage temperature	-40°C to +85°C

Values from the 3500/25 datasheet (141532 Rev. Y).

What a Keyphasor signal does for the rack

A Keyphasor mark on the shaft produces one pulse per revolution, or several per revolution on a gear or speed wheel. The module conditions that pulse with an automatic or manual threshold, then distributes the clean digital signal to every monitor in the rack. Monitors use it to calculate speed and to compute 1X amplitude and phase. Without a valid Keyphasor the tracking filters fall back to their nominal settings, and vector values become unreliable.

The Enhanced module adds once-per-turn event generation from multi-event inputs, field-upgradeable firmware and asset-management reporting while keeping form, fit and function with older Keyphasor modules.

125792-01 versus 149369-01

The older module offers the basic conditioning of Keyphasor pulses. The Enhanced replacement keeps downward compatibility but adds multi-event to once-per-turn processing, field-upgradeable firmware and asset-management reporting. For a legacy rack, either part can normally be fitted into the same half-height slot with the existing I/O module (125800-01, 126648-01 or the isolated versions), but the replacement unlocks the new configuration options only with compatible software.

If a spare stock of 125792-01 is not available, ordering 149369-01 is the manufacturer-recommended path. The datasheet figures shown above are those of the Enhanced module; for the older board no separate datasheet is attached, so the replacement figures act as a guide to function, not as a guarantee of identical specifications.

Selection and ordering checklist for 125792-01

Decide whether to buy the original 125792-01 or move to 149369-01.
Check the I/O module in the rack: 125800-01, 126648-01 or isolated versions.
Confirm the slot position (top or bottom half slot) and whether the half-height adapter is present.
Note the software version and firmware used for rack configuration.
State the condition required for an obsolete part: new surplus, tested or refurbished.

Installation, commissioning and maintenance

Install the half-height main module in a front slot (half-height modules need a mounting adapter in full-height slots; each rack may have only two main modules in the top and bottom half slots). Set the threshold mode to match the sensor: auto-threshold for clean Proximitor pulses, manual threshold for low-amplitude or noisy signals. Check the pulse count against the machine speed on the monitor display and confirm that front-panel OK and TX/RX LEDs are steady.

For magnetic pickups, remember that passive types need shaft speed above 200 rpm (3.3 Hz). Keep Keyphasor cabling separate from power cables and ensure shield grounding follows the plant standard.

Typical applications in Oman and the GCC

Keyphasor modules are present on every 3500 rack that measures speed or vector vibration on compressors, turbines, motors and pumps. In the GCC the sensors on the shaft are exposed to heat, oil mist and dust, so a clean signal and a firm probe mounting matter more than the module itself. Many plants in the region still run original 3500 racks, so an earlier-board spare can prevent a long outage when a Keyphasor channel fails.

Related 3500/25 part numbers

Part number	Item
149369-01	Enhanced Keyphasor Module (current spare)
125792-01	Earlier Keyphasor board, replaced by 149369-01
125800-01 / 126648-01	Keyphasor I/O, internal / external terminations
125800-02 / 126648-02	Isolated Keyphasor I/O (magnetic pickups), internal / external
135473-01	Keyphasor I/O with internal barriers and internal terminations
128718-01 / 128726-01	External termination blocks (Euro / terminal strip)

Information to send with your RFQ

Part number 125792-01 and quantity
Sensor type and number of Keyphasor signals required
Existing module and I/O part numbers in the rack
Agency approval and destination in Oman or the GCC

Documents and quotation

The manufacturer datasheet for the 3500/25 Enhanced Keyphasor Module is attached on this page; read it together with your rack configuration and the site specification before confirming an order. The attached datasheet describes the 3500/25 Enhanced module that supersedes this board.

Seven Star LLC is an independent supplier in Muscat serving Oman and the GCC. Stock position, lead time, condition and the certificates that travel with the shipment are confirmed in the written quotation.

Other Models in the 3500 25 Keyphasor Range

Seven Star LLC supplies models from the 3500 25 Keyphasor range in Oman and the GCC. Compare the related models below and request a quote for the one that matches your application.

Model	Category
Bently Nevada 3500/25-01-02-01 Enhanced Keyphasor Module	Vibration Monitoring	View details
Bently Nevada 125792-01 3500 Keyphasor Module Board	Vibration Monitoring	You are viewing this model

Datasheets & Documents

Datasheet Bently Nevada 3500/25 Keyphasor Datasheet Download

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About brand

Bently Nevada is the American machinery protection and condition monitoring brand behind the 3500 rack, the 3300 XL proximity probe and the System 1 software. It was founded in 1961 in Minden, Nevada, and is today a Baker Hughes business.

Seven Star LLC is an independent supplier in Muscat. We list Bently Nevada monitors, I/O modules, probes, proximitors, velocity transducers and transmitters for rotating equipment in Oman and the GCC, and source them by full part number.

Bently Nevada company profile

Established	1961, Minden, Nevada, USA, by Donald E. Bently. The business started earlier as Bently Scientific in Berkeley, California (1956).
Known for	The first commercial eddy-current proximity transducers for measuring shaft vibration and position on high-speed turbomachinery
Ownership	Acquired by GE Energy in 2002; part of Baker Hughes since GE Oil & Gas combined with Baker Hughes in 2017
Rack generations	5000 series (from 1965), 3300 series (from 1988), 3500 series (from 1995), Orbit 60 (current platform)
Product families	Machinery protection racks, proximity probes and proximitors, Keyphasor sensors, velocity and acceleration transducers, 2-wire vibration transmitters, general-purpose monitors, portable analyzers, wireless sensors and System 1 condition monitoring software
Typical machines	Steam and gas turbines, centrifugal and reciprocating compressors, pumps, motors, generators, fans and gearboxes

Milestones

1956: Donald E. Bently starts Bently Scientific in Berkeley, California.
1961: The company moves to Minden, Nevada, as Bently Nevada.
1965: The 5000 series monitoring system is introduced.
1988: The 3300 series follows.
1995: The 3500 machinery protection system is launched.
2002 and 2017: GE Energy acquires Bently Nevada; it becomes part of Baker Hughes in 2017.

Bently Nevada product series

Series	Type	What it does
3500	Machinery protection rack	Continuous online protection with alarm and danger relays. Modules include the 3500/15 power supply, 3500/20 rack interface, 3500/25 Keyphasor, 3500/42M proximitor/seismic, 3500/50 tachometer, 3500/60 temperature, 3500/33 relay and 3500/92 communication gateway
3500 recip modules	Reciprocating compressor monitoring	3500/70M impulse velocity, 3500/72M rod position and 3500/77M cylinder pressure
Orbit 60	Protection and monitoring platform	The current Bently Nevada platform for protection, condition monitoring and data integration with System 1
3300 XL 8 mm	Proximity transducer system	Probe, extension cable and proximitor sensor for radial vibration, thrust position and Keyphasor reference on fluid-film bearing machines; also 5 mm and 25 mm versions
330500 Velomitor, 190501 Velomitor CT	Piezo-velocity sensors	Casing velocity on rolling-element bearing machines and low-speed cooling tower fans
990 and 991	2-wire transmitters	4-20 mA vibration (990) and thrust position (991) signals straight into a PLC or DCS, without a monitor rack
1900/65A, 2300	Compact monitors	Protection for balance-of-plant pumps, fans and motors where a full 3500 rack is not justified

A proximity probe measures the gap to the shaft, so it sees shaft movement inside a fluid-film bearing directly. A velocity or acceleration sensor sits on the casing and suits rolling-element bearing machines. Critical turbomachinery usually carries two X-Y probes per bearing, two axial probes for thrust position and a Keyphasor probe for speed and phase.

Where Bently Nevada systems are used

In Oman and the GCC, Bently Nevada racks and probes protect gas turbines, compressors and steam turbines in gas processing, LNG, refining, petrochemical, power and desalination plants. Many installations are 3500 racks that have run for years, so most requests are for like-for-like module, probe, extension cable and proximitor replacements, plus upgrades to newer monitors.

Ordering and replacement: what we need

For probes and proximitors, send the full part number with all option digits (for example 330101-00-27-10-02-05). The digits set the probe length, cable length, connector and approvals, and the probe, cable and proximitor must match in total system length. For 3500 modules, send the module and I/O part numbers from the rack and say whether the I/O is internal or external termination, or barrier type. If a module is obsolete, we quote the replacement that Bently Nevada names and point out any configuration or firmware change.

Facts checked against Baker Hughes Bently Nevada pages and published company history, October 2026.

Browse Bently Nevada products by category: Vibration.