Bently Nevada 3500/44M Aeroderivative GT Vibration Monitor
Overview
The Bently Nevada 3500/44M Aeroderivative GT Vibration Monitor is a four-channel 3500 rack module designed for aeroderivative gas turbines. Unlike heavy-duty industrial turbines with fluid-film bearings and proximity probes, aeroderivative engines run on rolling element bearings inside a light casing, so their protection depends on casing-mounted velocity sensors and accelerometers and on filtering that can follow two or three spools turning at different speeds. The Bently Nevada 3500/44M continuously compares the monitored values with configured alarm setpoints to drive alarms and gives operations and maintenance staff the machine information they need.
Seven Star LLC supplies the Bently Nevada 3500/44M, its Aero GT, Prox/Velom and Multimode Prox/Velom I/O modules, termination blocks and cables on request to gas turbine operators in the Sultanate of Oman and across the GCC, with engineering support in Muscat. The manufacturer datasheet (143441 Rev. W) is attached to this page so the I/O options and channel types can be checked before an enquiry is sent.
Measurement Principle
The Bently Nevada 3500/44M accepts one to four signals from Velomitor sensors, accelerometers, or the Bently Nevada interface modules with part numbers 86517 and 86497. In the 3500 Rack Configuration Software each channel can be configured for signal integration, 1X vibration tracking and bandpass vibration. Because the monitor accepts two separate Keyphasor signals, each channel pair can track a different shaft, for example the gas generator and the power turbine. On the Aeroderivative channel type the tracking filter is valid from 60 to 240,000 cpm and is set by choosing one of 22 normal operating speeds from 2,400 to 18,000 rpm with a 3 or 5 Hz bandwidth; the bandpass filter offers a 200 Hz low-pass corner and high-pass corners of 25, 75 or 100 Hz with 10-pole roll-off.
The Aeroderivative 2 and Multimode Aeroderivative channel types widen the choice: non-integrated velocity from 4 to 5500 Hz, integrated velocity from 18 to 5500 Hz, non-integrated acceleration up to 30 kHz, configurable bandpass corners between 10 Hz and 5500 Hz with 8-pole filters, and a tracking filter selectable from 35 operating speeds between 2,400 and 30,000 rpm. Measured values include direct, bandpass, 1X amplitude and 1X phase lag, with bias for diagnostics. Multimode channels can hold up to eight sets of alarm parameters, each tied to a machine mode, and switch between them through contacts on the multimode I/O module or software commands from a communications gateway.
Engineering Design of the Bently Nevada 3500/44M
The Bently Nevada 3500/44M occupies one full-height front slot and one full-height rear slot, weighs 0.91 kg and draws 7.7 W typical. Its front panel provides OK, TX/RX and Bypass LEDs and one short-circuit-protected coaxial buffered output per channel at 550 Ω. Sensors are powered at 23 Vdc nominal, 43 mA maximum. Each channel also drives a +4 to +20 mA recorder output proportional to full scale, into 0 to 600 Ω with 0 to +12 Vdc compliance, a resolution of 0.3662 µA per bit and an update rate of 100 ms or less; a short on a recorder output does not affect the monitor.
Six I/O options for the Bently Nevada 3500/44M match the sensor arrangement. The Aero GT I/O, with input impedance above 95 kΩ, connects to the interface modules; the Prox/Velom I/O and Multimode Prox/Velom I/O present 10 kΩ for proximity and accelerometer inputs and 3.5 MΩ for Velomitor sensors, and the multimode versions add the mode input contacts. Each comes with internal or external terminations. Alert setpoints can be set on the measured values and Danger setpoints on up to two of them, with Danger delays of 0.1 second or 1 to 60 seconds and alarm accuracy within 0.13%.
Key Features
The manufacturer datasheet lists the following capabilities for the Bently Nevada 3500/44M:
- Four channels for Velomitor sensors, accelerometers or Bently Nevada interface modules.
- Signal integration, bandpass vibration and 1X tracking filter options per channel.
- Two Keyphasor inputs so each channel pair can track a different shaft speed.
- Tracking filters selectable from up to 35 normal operating speeds between 2,400 and 30,000 rpm.
- Multimode channels with up to eight alarm sets switched by contacts or gateway commands.
- Velocity scale factors of 100 or 145 mV/(in/s) and acceleration scale factors of 10, 25 or 100 mV/g.
- Short-circuit-protected buffered outputs and individual 4 to 20 mA recorder outputs.
- DNV GL and ABS marine classification, with cNRTLus, ATEX and IECEx approval options.
Industrial Applications
Aeroderivative gas turbines are widely used where fast starts, high power density or offshore weight limits matter: peaking and island power plants, gas compression on pipelines, mechanical drive on offshore and onshore production facilities, and LNG and gas processing utilities. In Oman such engines can be found driving generators in oil field power systems and compressors on gas networks. The Bently Nevada 3500/44M monitors casing vibration on the gas generator and power turbine, and its multimode alarm sets allow different limits during start-up, idle and loaded operation, so that normal transient vibration does not cause nuisance alarms while full protection applies at load.
A complete turbine rack typically combines the Bently Nevada 3500/44M with the Bently Nevada 3500/25 Keyphasor Module for the two speed references, the 3500/42M Proximitor Seismic Monitor for driven-equipment bearings, and the 3500/32M 4-Channel Relay Module for trip outputs. Seven Star LLC works with turbine owners and maintenance contractors in Oman and the GCC to identify the fitted I/O type, plan spares and supply the Bently Nevada 3500/44M for upgrades and outages.
Ordering Information
The datasheet gives the order code for the Bently Nevada 3500/44M as 3500/44-AA-BB, with these options:
| Option | Code | Description |
|---|---|---|
| A: I/O Module Type | 01 | Aero GT I/O Module with Internal Terminations |
| A: I/O Module Type | 02 | Aero GT I/O Module with External Terminations |
| A: I/O Module Type | 05 | Prox/Velom I/O Module with Internal Terminations |
| A: I/O Module Type | 06 | Prox/Velom I/O Module with External Terminations |
| A: I/O Module Type | 07 | Multimode Prox/Velom I/O Module with Internal Terminations |
| A: I/O Module Type | 08 | Multimode Prox/Velom I/O Module with External Terminations |
| B: Hazardous Area Approval | 00 | None |
| B: Hazardous Area Approval | 01 | cNRTLus (Class 1, Division 2) |
| B: Hazardous Area Approval | 02 | ATEX/IECEx/CSA (Class 1, Zone 2) |
Part numbers listed for the Bently Nevada 3500/44M termination hardware, cables and spares:
| Part Number | Description |
|---|---|
| 176449-03 | 3500/44M Aeroderivitive GT Vibration Monitor |
| 126599-01 | Aero GT I/O Module Internal Terminations |
| 140471-01 | Prox/Velom I/O Module with Internal Terminations |
| 140482-01 | Prox/Velom I/O Module with External Terminations |
| 169459-01 | Multimode Prox/Velom I/O Module with Internal Terminations |
| 169459-02 | Multimode Prox/Velom I/O Module with External Terminations |
| 125808-03 / 128015-03 | Aeroderivative External Termination Block (Euro Style / Terminal Strip connectors) |
| 125808-08 / 128015-08 | Prox/Velom External Termination Block (Euro Style / Terminal Strip connectors) |
| 125808-11 / 128015-11 | Multimode Prox/Velom External Termination Block (Euro Style / Terminal Strip connectors) |
| 125808-13 / 128015-13 | Multimode Recorder Output and Mode Input External Termination Block (Euro Style / Terminal Strip connectors) |
| 128702-01 / 128710-01 | Recorder External Termination Block (Euro Style / Terminal Strip connectors) |
| 129525-AAAA-BB | 3500 Transducer (XDCR) to External Termination (ET) Block Cable; AAAA 0005, 0007, 0010, 0025, 0050 or 0100 feet; BB 01 not assembled, 02 assembled |
| 129529-AAAA-BB | 3500 Recorder Output to External Termination (ET) Block Cable; same codes |
| 00580434 / 00580432 | Euro Style connector header, 8 pin / 10 pin, green, for I/O modules with internal terminations |
| 166M2389 / 166M2388 | Connector Header, Push-in-Spring Type (alternatives for PN 00580434 / 00580432) |
| 00561941 | Prox/Velom and Multimode Prox/Velom I/O Module ten-pin connector shunt |
| 143490-01 | 3500/44M Aeroderivitive GT Vibration Monitor User Guide |
Technical Specifications
Key Bently Nevada 3500/44M data from datasheet 143441 Rev. W:
| Parameter | Specification |
|---|---|
| Model | Bently Nevada 3500/44M Aeroderivative GT Vibration Monitor |
| Inputs | 1 to 4 signals from interface modules (86517, 86497), Velomitor sensors and accelerometers |
| Input impedance | Aero GT I/O >95 kΩ; Prox/Velom and Multimode I/O 10 kΩ (prox/accel), 3.5 MΩ (Velomitor) |
| Sensitivity | Aeroderivative: 100 or 145 mV/(in/s); Aeroderivative 2 and Multimode: 100 or 145 mV/(in/s), 100, 25 or 10 mV/g |
| Accuracy | Within ±0.33% of full scale typical, ±1% maximum, not including filter effects |
| Frequency response | Aeroderivative direct 4 Hz to 30 kHz; Aeroderivative 2 velocity 4–5500 Hz, acceleration 4–30,000 Hz |
| Tracking filter | Constant Q; 22 speeds 2,400–18,000 rpm (Aeroderivative) or 35 speeds 2,400–30,000 rpm (Aeroderivative 2 / Multimode); 3 or 5 Hz bandwidth |
| Measured values | Direct, bandpass, 1X amplitude, 1X phase lag, bias; Direct-B, Bandpass-B, 1X Ampl-B and Mode on multimode channels |
| Transducer power | 23 Vdc nominal, 43 mA maximum |
| Buffered outputs | One coaxial per channel, 550 Ω, short-circuit protected |
| Recorder outputs | +4 to +20 mA per channel; 0 to +12 Vdc compliance; 0 to 600 Ω; 0.3662 µA per bit; 100 ms or less update |
| Alarm delays | Alert 1–60 s in 1 s steps; Danger 0.1 s or 1–60 s in 1 s steps |
| Power consumption | 7.7 W typical |
| Monitor dimensions / weight | 241.3 × 24.4 × 241.8 mm; 0.91 kg |
| I/O module dimensions / weight | 241.3 × 24.4 × 99.1 mm; 0.45 kg |
| Approvals | FCC Part 15; EMC and LV directives; RoHS; DNV GL; ABS; cNRTLus Class I Div 2 / Zone 2; ATEX/IECEx II 3 G |
How to Order
To request a quotation for the Bently Nevada 3500/44M, send Seven Star LLC the full order code, or the turbine model, sensor types and scale factors, the number of Keyphasor references and whether multimode alarming is needed. Our team in Muscat will confirm availability, lead time and the termination hardware for your rack, and the datasheet can be downloaded from the documents tab on this page. We supply the Bently Nevada 3500/44M to customers in Oman and the GCC.
- Datasheet Bently Nevada 3500/44M Aeroderivitive GT Vibration Monitor Datasheet (143441 Rev. W) Download
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.
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