Brand: Bently Nevada

Bently Nevada 3500/91 EGD Communication Gateway Module

Name: Bently Nevada 3500/91 EGD Communication Gateway
Brand: Bently Nevada
SKU: 3500/91

Description

Bently Nevada 3500/91 EGD communication gateway for GE controller integration

The Bently Nevada 3500/91 EGD Communication Gateway is the 3500 rack module that publishes monitor values and statuses over Ethernet Global Data (EGD), the protocol used by GE Mark VIe and other EGD-compatible controllers. It is a main module with a rear Ethernet I/O module, and it turns a 3500 machinery protection rack into a data source for the turbine or compressor control system. The part number 3500/91 identifies the gateway; the manufacturer’s spares are 161204-01 for the gateway module and 161216-01 or 161216-02 for the I/O module.

It is a communication path, not a protection path: it transfers rack, module and channel status, alarm values and setpoints without interfering with machinery protection. Seven Star LLC supplies the 3500/91 in Oman and the GCC as an independent supplier in Muscat.

3500/91 technical specifications

Parameter	Specification
Manufacturer / part number	Bently Nevada (Baker Hughes) / 3500/91
Protocols	EGD version 2.01; Ethernet UDP/IP frames
Ethernet standard	IEEE 802.3 CSMA/CD, 10 and 100 Mbps, conforming to IEEE 802.3 and 802.3u
Physical layer options	RJ-45 jack, 10BASE-T/100BASE-TX twisted pair, or MT-RJ jack for 100BASE-FX fiber
Produced data	Rack, module and channel status; data values (float); setpoints (float)
Consumed data	Group Reset, Group Trip Multiply, Group Alarm Inhibit, Group Special Alarm Inhibit
Power consumption	7.4 W typical
Main module size	241.3 x 24.4 x 241.8 mm (9.50 x 0.96 x 9.52 in), 0.79 kg (1.75 lb)
I/O module size	241.3 x 24.4 x 99.1 mm (9.50 x 0.96 x 3.90 in), 0.39 kg (0.85 lb)
Rack space	One full-height front slot and one full-height rear slot
Operating temperature	-30 to +65 °C (-22 to +150 °F)
Storage / humidity	-40 to +85 °C (-40 to +185 °F); 95 percent non-condensing
LEDs	OK (module healthy) and TX/RX (communicating with other rack modules)

Decoding 3500/91-AA-BB-CC

Field	Code	Meaning	Spare part
A: main module	01	EGD communication gateway module	161204-01
B: I/O module	01	Ethernet 10BASE-T/100BASE-TX I/O module (RJ-45)	161216-01
	02	Ethernet 100BASE-FX I/O module (MT-RJ fiber)	161216-02
C: agency approval	00 / 01 / 02	None / CSA/NRTL/C / CSA/A as printed in the datasheet	Set on the assembly

How the gateway exchanges data

EGD works by producers sending periodic data exchanges on the network and consumers picking up the exchanges they need. The 3500/91 is a producer of values and status and a consumer of control commands. In the produced exchanges, floating-point measured values and setpoints are published for each monitor channel, along with status words for the rack, each module and each channel. Because the exchanges repeat at a fixed rate, the control system always has a recent copy of vibration, position or temperature values without polling.

In the consumed direction, the controller can send group commands such as alarm reset, trip multiply and alarm inhibit to the rack, so common operating actions need not be wired through relay contacts. The datasheet limits the module to one EGD gateway per rack.

Where the 3500/91 fits in the 3500 system

The gateway needs a 3500/22M Transient Data Interface to communicate with the monitor modules, along with Rack Configuration Software 3.70 or higher and TDI firmware 1.20 or higher, as stated in the ordering considerations. Consumed-exchange support needs 4-channel monitor firmware 2.21 or later. Other gateways in the family are the 3500/92 for Modbus and the 3500/94M, which can sit in the same rack where redundant communication or several protocols are needed.

3500/22M TDI: the rack interface the gateway depends on.
3500/92 Comm Gateway: Modbus serial and Ethernet.
161232: 3500/91 user guide.
Network accessories are described in the separate manufacturer network accessories datasheet (164466).

Selection checklist for the 3500/91

Confirm that the controller supports EGD v2.01, as GE Mark VIe does, and that the exchange configuration is planned with the controls engineer.
Select the I/O type: copper RJ-45 (161216-01) for panel-to-panel runs inside the control room, or MT-RJ fiber (161216-02) for longer runs and electrical isolation.
Check that the rack has a 3500/22M TDI and compatible firmware and software.
Plan one 3500/91 per rack, with a second gateway of another protocol if a historian also needs data.
Treat analog and digital communication as annunciation and trending, not as the auto-shutdown path; hard-wired relays remain the recommended method.

Installation, commissioning and maintenance

Install the main module and rear I/O module in a free slot to the right of the TDI. Set IP parameters and exchange configuration through the Rack Configuration Software and load the matching exchange file into the controller. Test with a network analyzer or the controller diagnostics, verifying the exchange period and that status words change when an alarm is simulated.

Document the switch port, VLAN and cabling used. In operation, watch the TX/RX LED and the controller’s communication-loss alarm. Keep a spare gateway module and the correct I/O module (copper or fiber) in the store, because the two I/O types are not interchangeable.

Typical applications in Oman and the GCC

GE heavy-duty and aeroderivative gas turbines are widely used for power generation, desalination and oil and gas in Oman and the GCC, and many are controlled by Mark VIe systems. The 3500/91 lets the turbine controller display vibration, bearing temperature and position data from the 3500 rack on its own HMI and historian, and to receive reset commands. The same gateway fits mechanical-drive compressors and pumps where the unit controller is EGD-capable.

Information to send with your RFQ for the 3500/91

Full ordering code (3500/91-AA-BB-CC) or spare numbers 161204-01 and 161216-01 or -02, plus quantity.
Photo of the existing gateway label and revision.
Controller type, Ethernet medium (copper or fiber) and rack TDI model.
Delivery country and required date.

Documents and quotation

The 3500/91 EGD Communication Gateway datasheet is attached on this page and is the reference for the figures above. Send the 3500/91 code you need and the rack details with your request.

Seven Star LLC quotes for Oman and the GCC with stock position, condition and lead time stated.

Datasheets & Documents

Datasheet Bently Nevada 3500/91 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 Bently Nevada 3500/91 EGD Communication Gateway

Answers from our engineering team on installation, compatibility and integration.

01What does the Bently Nevada 3500/91 do?

It publishes rack, module and channel status, measured values and setpoints from a 3500 rack over Ethernet Global Data (EGD) version 2.01, so EGD-compatible controllers such as GE Mark VIe can read them.

02Which Ethernet options does the 3500/91 offer?

Two I/O modules: 161216-01 with an RJ-45 jack for 10BASE-T/100BASE-TX twisted pair, and 161216-02 with an MT-RJ jack for 100BASE-FX fiber.

03Can the controller send commands to the rack?

Yes. The consumer exchange accepts Group Reset, Group Trip Multiply, Group Alarm Inhibit and Group Special Alarm Inhibit commands.

04What does the 3500/91 require in the rack?

A 3500/22M TDI with firmware 1.20 or higher and Rack Configuration Software 3.70 or higher. Only one EGD gateway is allowed per rack.

05Is the 3500/91 suitable for machinery shutdown?

The manufacturer recommends relays for auto-shutdown interconnects. The digital gateway is intended for annunciation, display and trending, not for the protection path.