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Brand: Bently Nevada
3500/40M Proximitor® Monitor
Description
Overview
The Bently Nevada 3500/40M is a four-channel Proximitor monitor for the 3500 series machinery protection rack, processing signals from Bently Nevada proximity transducers to continuously track radial vibration, eccentricity, thrust position, differential expansion, and bearing condition (REBAM) on rotating machinery. Its ability to configure channel pairs for multiple measurement types from one module simplifies rack design compared with dedicating separate single-purpose monitors to each parameter.
As a core measurement module in the widely deployed Bently Nevada 3500 platform, the 3500/40M is engineered for continuous, safety-critical protection of turbines, compressors, and other high-value rotating equipment. Seven Star LLC supplies the Bently Nevada 3500/40M Proximitor monitor to power generation, oil and gas, and process facilities across Oman and the GCC.
Operating Principle
The 3500/40M accepts signals from up to four Bently Nevada proximity transducers, processing them through programmable signal conditioning to derive the configured measurement type for each channel pair. Each channel provides a buffered transducer output through its own coaxial connector, with 550Ω output impedance and short-circuit protection, letting the raw or conditioned transducer signal be tapped for external data acquisition or portable diagnostic equipment without disturbing the protection function.
Engineering Design of the Bently Nevada 3500/40M
The monitor supports independently configurable alert and danger alarm thresholds across its four channels, adjustable from 0 to 100% of full-scale with accuracy within 0.13% of the desired setpoint. Programmable time delays (Alert 1 to 60 seconds, Danger 0.1 second or 1 to 60 seconds; longer for REBAM channels) prevent nuisance trips from transient spikes while still responding quickly to genuine fault conditions. Three front-panel LEDs (OK, TX/RX communication, Bypass) give at-a-glance module status, and the monitor supports channel-pair configuration for radial vibration, eccentricity, thrust position, differential expansion, and REBAM bearing-condition measurement.
Key Features
- Four-channel Proximitor signal monitoring
- Configurable for radial vibration, eccentricity, thrust, differential expansion, REBAM
- Alarm setpoints adjustable 0–100% full-scale, ±0.13% accuracy
- Programmable alarm time delays, 0.1–60 seconds
- Buffered coaxial transducer outputs per channel, 550Ω impedance
- Short-circuit protected outputs
- Three front-panel status LEDs (OK, TX/RX, Bypass)
- Compatible with the full Bently Nevada 3500 rack platform
Industrial Applications
The 3500/40M is used for continuous vibration, position, and bearing-condition monitoring on turbines, compressors, and generators in power generation, oil and gas, and petrochemical facilities across Muscat, Sohar, and Salalah, where machinery protection systems must reliably detect developing mechanical problems before they cause catastrophic failure or unplanned shutdown.
Across the GCC’s power and process industries, the 3500/40M’s configurable channel pairs let one module cover multiple measurement types on a single machine train, while its buffered outputs support portable vibration analyzers and condition-monitoring software tapping the same transducer signals used for the protection function, without adding separate instrumentation.
Technical Specifications
| Parameter | Specification |
|---|---|
| Model | Bently Nevada 3500/40M |
| Channels | 4 |
| Measurement Types | Radial vibration, eccentricity, thrust, differential expansion, REBAM |
| Alarm Range | 0–100% full-scale, ±0.13% accuracy |
| Alarm Time Delay | Alert: 1 to 60 s in 1 s steps; Danger: 0.1 s or 1 to 60 s in 0.5 s steps; REBAM channels up to 400 s |
| Output | Buffered coaxial per channel, 550Ω, short-circuit protected |
| Status Indicators | OK, TX/RX, Bypass LEDs |
| Power consumption | 7.7 W typical |
| Input impedance (standard I/O) | 10 kΩ |
| Transducer power supply | -24 Vdc |
| Sensitivity – radial vibration, thrust, eccentricity | 3.94 mV/µm (100 mV/mil) or 7.87 mV/µm (200 mV/mil) |
| Sensitivity – differential expansion | 0.394 mV/µm (10 mV/mil) or 0.787 mV/µm (20 mV/mil) |
| Sensitivity – REBAM | 40 mV/µm (1000 mV/mil) or 80 mV/µm (2000 mV/mil) |
| Radial vibration Direct filter | User-programmable, single-pole, 4 Hz to 4000 Hz or 1 Hz to 600 Hz |
| Accuracy – Direct, Gap, 1X and 2X | Within ±0.33% of full-scale typical, ±1% maximum |
| Valid machine speed for 1X/2X vector, Not 1X and Smax | 60 cpm to 60,000 cpm |
| Operating temperature | -30 °C to +65 °C with internal/external termination I/O; 0 °C to +65 °C with internal barrier I/O |
| Storage temperature / humidity | -40 °C to +85 °C / 95%, noncondensing |
| Monitor module dimensions (H x W x D) / weight | 241.3 mm × 24.4 mm × 241.8 mm / 0.91 kg (2.0 lb) |
| I/O module dimensions (H x W x D) / weight | Non-barrier: 241.3 × 24.4 × 99.1 mm, 0.20 kg; barrier: 241.3 × 24.4 × 163.1 mm, 0.46 kg |
| Approvals | cNRTLus Class I Division 2 Groups A, B, C, D and Class I Zone 2; ATEX/IECEx II 3 G (II 3(1) G with internal barriers); ABS and DNV GL maritime |
Identifying the Correct 3500/40M Module
When replacing or extending a monitor in an existing rack, confirm the exact part number printed on the module label and the matching I/O module behind it. The Bently Nevada 3500/40M works together with a dedicated I/O module in the rear of the rack, and the I/O type must suit the field wiring (internal or external terminations, and any barrier requirement for hazardous-area transducers). Also note the firmware revision and the rack configuration software version in use, because the module must be configured from the saved rack configuration before it is returned to service.
- Record the module part number, serial number and slot position
- Identify the associated I/O module and termination type
- Note the transducer system (probe, extension cable and Proximitor sensor) on each channel
- Export the current rack configuration before any change
Installation and Commissioning
The monitor slides into a standard 3500 rack slot and can typically be inserted with the rack powered, but alarm and relay logic must be considered before doing so. Place the channels in bypass or inhibit where your site procedure requires, download the channel-pair configuration, then verify each channel with a calibrated signal source or a proximity probe test kit. Check that alert and danger setpoints, time delays and full-scale ranges match the machinery protection philosophy, and confirm the buffered outputs read correctly on a portable analyzer.
Maintenance and Troubleshooting
Most channel faults originate in the field, not in the module. A NOT OK status usually points to gap voltage outside limits, a damaged extension cable, a loose connector or a failed Proximitor sensor. Check the gap voltage at the buffered output first, then the transducer chain. Keep the rack configuration file under revision control, and plan periodic channel verification in line with your protection system test schedule.
Machinery Protection in Oman and the GCC
The 3500/40M is common on gas turbines, steam turbines, centrifugal compressors and large pumps in regional power stations, gas processing plants and refineries, where reliable radial vibration and thrust monitoring is part of the trip philosophy.
Sourcing from Seven Star LLC
Seven Star LLC supplies the Bently Nevada 3500/40M and related 3500 rack modules for new racks and spare holdings. Send the module label details and rack layout, and our team will help confirm the matching I/O module and accessories.
For spare holdings, many sites keep at least one pre-tested monitor per rack type so that a failed channel can be restored within a single maintenance window.
3500/40M Ordering Information and Part Numbers
The monitor is ordered as 3500/40M-AA-BB. Field A selects the I/O module: 01 is the Proximitor I/O Module with Internal Termination, 02 is the Proximitor I/O Module with External Terminations, and 03 is the Proximitor I/O Module with Internal Barriers and Internal Terminations. Field B selects the hazardous area approval: 00 for none, 01 for cNRTLus (Class 1, Division 2) and 02 for ATEX / IECEx / CSA (Class 1, Zone 2). Bently Nevada states that approval option B-02 is only available together with ordering option A-03.
For spares, the main board is 176449-01 (3500/40M Proximitor Monitor). The matching rear modules are 125680-01 (Proximitor I/O Module with Internal Terminations), 126615-01 (Proximitor I/O Module with External Terminations) and 135489-04 (Proximitor I/O Module with Internal Barriers and Internal Terminations). Field connector headers are 00580434 (Euro style, 8-pin) and 00502133 (Euro style, 12-pin), with 166M2389 offered as a push-in-spring alternative to 00580434. The user guide is document 143488.
External termination hardware is not included with an external-termination I/O module and has to be ordered separately for each module: 125808-01 is the Proximitor ET Block with Euro Style Connectors and 128015-01 is the Proximitor ET Block with Terminal Strip Connectors. The transducer signal cable to the ET block is 129525-AAAA-BB, where AAAA is the length (0005, 0007, 0010, 0025, 0050 or 0100 feet, that is 1.5 m to 30.5 m) and BB is 01 for not assembled or 02 for assembled.
3500/40M Configuration, Compatibility and Alarm Timing
Channels are programmed in pairs with 3500 Rack Configuration Software, so one module can run up to two functions at once: channels 1 and 2 take one channel type and channels 3 and 4 take the same or a different one. Alert setpoints can be assigned to every active static value, while Danger setpoints are limited to any two of them. For radial vibration the monitor returns Direct, Gap, 1X and 2X amplitude and phase lag, Not 1X amplitude and Smax amplitude; thrust and differential expansion return Direct and Gap.
The module needs 3500/01 software version 2.50, 3500/02 version 2.20 and 3500/03 version 1.21 or later. The REBAM channel type additionally needs module firmware revision 2.1, 3500/01 version 3.30, 3500/02 version 2.40, 3500/03 version 1.40 and DM2000 version 3.40. Alarm delays differ by channel type: for vibration, thrust, differential expansion and eccentricity, Alert is 1 to 60 s in 1 s steps and Danger is 0.1 s or 1 to 60 s in 0.5 s steps; REBAM delays run from a calculated minimum up to 400 s. External termination blocks cannot be combined with internal-termination I/O modules.
3500/40M Codes Buyers Search For
Searches for this monitor use several different codes: the full ordering code, the main board number printed on the module, or the part number of the rear I/O module. This list explains how they relate, using the ordering rules above.
- 3500/40M-01-00: monitor with Proximitor I/O Module with Internal Terminations, no hazardous area approval. 3500/40M-02-00 uses the external-termination I/O module, and 3500/40M-03-00 the I/O module with internal barriers. 3500/40M-03-02 adds ATEX / IECEx / CSA approval, which is only offered with option 03.
- 3500/40: many buyers search without the M. We quote against the full code shown on the module label, so please send a photo of it.
- 176449-01: the spare main board listed in the current datasheet. Older modules in service are often labelled with board number 140734-01, shown with the PWA prefix as PWA 140734-01 (searched as 3500/40M-PWA140734-01), and current boards as PWA 176449-01; send the label and we will confirm the replacement before quoting.
- 125680-01, 126615-01 and 135489-04: the three rear I/O modules (internal terminations, external terminations, internal barriers). See the 125680-01 I/O module and the 135489-04 barrier I/O module. Other 135489 dash numbers, such as -05 and -06, are different barrier I/O variants, so match them to your monitor from the label.
- 125808-01: the Proximitor ET block with Euro style connectors, used only with the external-termination I/O module.
- 3500/42M: a different monitor, the 3500/42M Proximitor/Seismic Monitor, which also accepts seismic (velocity and acceleration) transducers.
Request a Quote for 3500/40M Proximitor® Monitor
Contact Seven Star LLC for a quotation and availability on the Bently Nevada 3500/40M Proximitor monitor across Oman and the GCC. Our team can help configure the correct channel-pair measurement setup for your machinery protection rack.
Browse the full Bently Nevada range or see more Vibration products supplied by Seven Star LLC in Oman and the GCC.
Other Models in the Bently Nevada 3500 Machinery Protection System Range
Seven Star LLC supplies models from the Bently Nevada 3500 Machinery Protection System 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 Machinery Protection System | Vibration Monitoring | View details |
| 3500/15 AC/DC Power Supply Module | Vibration Monitoring | View details |
| 3500/25 Keyphasor® Module | Vibration Monitoring | View details |
| 3500/22M Transient Data Interface (TDI) | Vibration Monitoring | View details |
| Bently Nevada 3500/33 16-Channel Failsafe Relay Output Module – 149992-02 | Vibration Monitoring | View details |
| Bently Nevada 3500/32M 4-Channel Relay Module | Vibration Monitoring | View details |
| 3500/40M Proximitor® Monitor | Vibration Monitoring | You are viewing this model |
| Bently Nevada 3500/42M Proximitor Seismic Monitor | Vibration Monitoring | View details |
| Bently Nevada 3500/45 Position I/O Module – 135137-01 | Vibration Monitoring | View details |
| Bently Nevada 3500/50 Tachometer Module | Vibration Monitoring | View details |
| 3500/60 Temperature Monitor | Vibration Monitoring | View details |
| Bently Nevada 3500/60-01-00 Temperature Monitor Module | Vibration Monitoring | View details |
Datasheets & Documents
- Datasheet Bently Nevada 3500/40M Proximitor Monitor 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.
FAQ
Questions about the 3500/40M Proximitor® Monitor
Answers from our engineering team on installation, compatibility and integration.
01What does the 3500/40M Proximitor Monitor measure and how many channels does it have?
It is a 4-channel monitor for the Bently Nevada 3500 rack, with each channel independently configurable for Radial Vibration, Thrust Position, Differential Expansion, Eccentricity, or REBAM using eddy-current proximity transducers.
02How does the 3500/40M combine protection with diagnostics?
It continuously compares derived static values (overall level, gap/position) against user-programmable Alert/Danger setpoints with time delays and latching for protection, while separately streaming dynamic waveform and orbit data to System 1 through a 3500/22M Transient Data Interface (TDI) for condition-based diagnostics.
03What industry standard is the 3500/40M designed to support?
As part of the modular Bently Nevada 3500 machinery protection system, it is designed to help meet API 670 requirements for critical rotating machinery protection.
04Can the 3500/40M be replaced without shutting down the protected machine?
Yes, it is a hot-swappable 4-channel card with front-panel LEDs reporting OK/fault status, so a card can be replaced while the rack and protection loop for other channels remain in service.
05What information does Seven Star LLC need to confirm compatibility before ordering a 3500/40M?
The probe model and cable lengths, the intended channel mix (for example two radial plus one thrust), and the System 1/TDI details are needed to confirm firmware compatibility, I/O, and correct slot positioning against your site's alarm philosophy.
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