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Brand: Bently Nevada
Bently Nevada 128229-01 3500/42M Prox/Seismic I/O Module
Description
Bently Nevada 128229-01 3500/42M Prox/Seismic I/O module with internal terminations
The Bently Nevada 128229-01 is the standard rear I/O module of the 3500/42M Proximitor Seismic Monitor. It is the I/O type 01 in the ordering code: a Prox/Seismic module with internal terminations, meaning the field wiring lands on plug-in connector headers on the module itself and no external termination block is needed. It carries signals for proximity probes with Proximitors, accelerometers, Velomitor sensors and Seismoprobe velocity transducers.
Seven Star LLC supplies this module to plants in Oman and the GCC as a spare for existing 3500/42M racks and for new rack builds.
128229-01 technical specifications
| Parameter | Specification |
|---|---|
| Manufacturer / part number | Bently Nevada 128229-01 |
| Description | 3500/42M Prox/Seismic I/O module with internal terminations |
| Ordering option in 3500/42M code | AA = 01 |
| Supported transducers | Proximitor, Seismoprobe, Prox/Accel and Velomitor; Seismoprobe, Prox/Accel and Velomitor are noted as supported but not recommended |
| Rack position | 1 full-height rear slot, behind the 3500/42M main module |
| Output supply, Prox/Accel and Velomitor | 23.9 V, 45.5 mA, 1.09 W |
| Output supply, Seismoprobe | 6.82 V, 2.75 mA, 0.02 W |
| Dimensions, non-barrier I/O | 241.3 x 24.4 x 99.1 mm (9.50 x 0.96 x 3.90 in), 0.20 kg (0.44 lb) |
| 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 |
| Humidity | 95%, non-condensing |
| Connector headers (spares) | 00580434 (8-pin Euro style) and 00580432 (10-pin), push-in-spring alternatives 166M2389 and 166M2388 |
Data from the 3500/42M datasheet.
How it connects the field to the monitor
The I/O module is the barrier between plant cabling and the monitor electronics. Transducer signals arrive on the connector headers, pass over the rack backplane to the main board and are returned as buffered outputs. Four transducer channels are available, programmed in pairs by the monitor. Power for the transducers is -24 Vdc, and the output-supply parameters in the datasheet table matter when a safety barrier is added externally.
Because no barriers are inside the module, it is intended for non-hazardous or Zone 2 / Class I Division 2 installations where the field circuits are not required to be intrinsically safe. If barriers are needed the 135489 family is the corresponding choice.
Compatible modules and alternatives
The matching front module is the 3500/42M monitor (176449-02, or the 140734-02 board). 128240-01 is the external-termination twin of this module and requires an external termination block and cable ordered separately; the datasheet warns that external termination blocks cannot be used with internal-termination I/O modules. For intrinsic safety use 135489-01, 135489-02 or 135489-03. For shaft absolute measurement use 138708-01. Newer Prox/Velom I/O modules 140471-01 and 140482-01 add support for high-temperature velocity sensors.
| Part number | I/O description |
|---|---|
| 128229-01 | Prox/Seismic I/O, internal terminations (ordering option 01) |
| 128240-01 | Prox/Seismic I/O, external terminations (02) |
| 135489-01 | Internal barriers, internal terminations, 4 x Prox/Accel (04) |
| 135489-02 | Internal barriers, 2 x Prox/Accel and 2 x Velomitor (05) |
| 135489-03 | Internal barriers, 4 x Velomitor (06) |
| 138708-01 / 138700-01 | Shaft absolute I/O, internal / external terminations (07 / 08) |
| 140471-01 / 140482-01 | Prox/Velom I/O, internal / external terminations (09 / 10) |
Selection and ordering checklist for 128229-01
- Confirm the field sensors: Proximitor probes, accelerometers or Velomitors are fine, Seismoprobe is supported but not the recommended choice.
- Check that the area classification does not require barriers.
- Decide internal or external terminations, and do not mix them with the wrong termination blocks.
- Order spare connector headers when the module will be removed for repair.
- State the agency approval of the full 3500/42M assembly.
Installation and maintenance
Fit the I/O module in the rear slot before the front monitor. Label the cables, wire each header with the shield terminated as in your standard, and confirm the earth bonding at the signal common. When swapping a module on a running machine, put the monitor in bypass first, then check gap voltage and the OK LED when you restore it. Keep spare headers, since pins bend easily under frequent removal.
Use in Oman and the GCC
The 128229-01 is one of the most common 3500 rear modules in turbomachinery plants in the region. Typical cases are bearing monitoring on gas turbine driven compressors, power plant boiler feed pumps and fan drives in desalination plants, where both proximity probes and a Velomitor on the casing are installed.
Wiring practice for 128229-01 connector headers
The 128229-01 uses plug-in Euro style headers (8-pin 00580434 and 10-pin 00580432 listed as spares in the datasheet). Strip cable ends cleanly, fit ferrules on stranded conductors and tighten the screw terminals to the manufacturer torque. Group the signal, common and -24 V conductors consistently on every channel so a technician can recognise a channel by its pattern.
When a 128229-01 is replaced, take a photograph of the old terminations and check the new module’s position in the rack before releasing the monitor from bypass. For a different layout, such as casing sensors only, the 140471-01 Prox/Velom module may be the better alternative.
Information to send with your RFQ
- Part number 128229-01 and quantity
- 3500/42M monitor part number and firmware
- Transducer type for each channel
- Delivery location in Oman or the GCC
Related Bently Nevada products: Bently Nevada 128240-01 3500/42M Prox/Seismic I/O Module, Bently Nevada 125680-01 3500/40M Proximitor I/O Module, Bently Nevada 3500/42M Proximitor Seismic Monitor, Bently Nevada 3500/45 Position I/O Module – 135137-01, Bently Nevada 135489-04 3500/40M Proximitor Internal Barrier I/O and Bently Nevada 3500/20 Rack Interface Module.
Documents and quotation
The manufacturer datasheet for the 3500/42M monitor and its I/O modules is attached on this page; read it together with your rack configuration and the site specification before confirming an order.
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.
Datasheets & Documents
- Datasheet Bently Nevada 3500/42M 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.
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Frequently Asked Questions
What is the 128229-01?
It is the Prox/Seismic I/O module with internal terminations for the 3500/42M, ordering option 01. Field wiring lands directly on its connector headers.
Which monitor does it work with?
It is a rear I/O module for the 3500/42M Proximitor Seismic Monitor, installed in the full-height rear slot behind the monitor.
Does it need an external termination block?
No. External termination blocks cannot be used with internal-termination modules. The external version is 128240-01.
What temperature range applies to barrier I/O modules?
The datasheet gives 0°C to +65°C for the internal barrier I/O with internal terminations, against -30°C to +65°C for the other I/O modules.
What documents help with selection?
The 3500/42M datasheet lists all I/O modules with their ordering options, supply parameters and spares. The internal barrier datasheet 141495 applies to barrier modules.
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