Bently Nevada 3500/46M Hydro Monitor
Overview
The Bently Nevada 3500/46M Hydro Monitor is a four-channel module for the Bently Nevada 3500 rack built for the slow, large machines of hydroelectric plants. It accepts proximity, seismic, dynamic pressure and air gap sensors and conditions them into vibration, position, and static and dynamic pressure measurements, which are then compared with user-programmable alarms. A distinctive function is the Hydro Radial Vibration channel, which combines shaft gap movement with NX amplitude into a composite value used to alarm on shear-pin failure in the wicket gate mechanism.
Seven Star LLC supplies the Bently Nevada 3500/46M, its Prox/Velom, Multimode Prox/Velom and Multimode Positive Input I/O modules, termination blocks and cables from Muscat, with engineering support for customers in the Sultanate of Oman and the GCC. The manufacturer datasheet (144408 Rev. AD) is attached to this page so that channel types, sensor scale factors and part numbers can be confirmed before ordering.
Measurement Principle
Channels of the Bently Nevada 3500/46M are programmed in pairs, and each channel can be set to Hydro Radial Vibration, Hydro Air Gap, Hydro Velocity, Hydro Acceleration, Hydro Thrust or Hydro Stator End Winding (SEW), or to the multimode versions of radial vibration, air gap, velocity, thrust, acceleration and dynamic pressure. Radial vibration is filtered from 0.104 Hz to 500 Hz for rotor speeds of 25 to 1,500 cpm, with a gap filter at 0.05 Hz, a Not 1X notch, and 1X and NX vector filters where N can be chosen from 2 to 20, or 2 to 50 for machines up to 600 cpm. The composite value is the NX amplitude multiplied by the percentage change in gap from its zero position, which is specific to detecting shear-pin failure.
Air gap channels use air gap sensors in the generator to measure each pole gap, then report average, minimum and maximum air gap per revolution and the pole numbers at which the minimum and maximum occur, while the pole-passing rate is between 1 and 200 poles per second; an instantaneous air gap value is available when rotation slows below one pole per second. Hydro Velocity channels give early warning and diagnostic data, but the datasheet states that because of high-amplitude, low-frequency velocity events they cannot be used for automated machinery protection. The SEW channel measures stator end winding vibration from 100 mV/g accelerometers over 5 to 800 Hz and reports pole-pass amplitude.
Engineering Design of the Bently Nevada 3500/46M
The Bently Nevada 3500/46M occupies one full-height front slot and one full-height rear slot, weighs 0.91 kg and draws 7.7 W typical. The front panel carries OK, TX/RX and Bypass LEDs and one short-circuit-protected coaxial buffered output per channel at 550 Ω. Prox/Velom and Multimode Prox/Velom I/O modules supply −23 Vdc at up to 43 mA and present 10 kΩ to proximity and acceleration inputs or 3.5 MΩ to Velomitor sensors, while the Multimode Positive Input I/O supplies +23 Vdc at up to 23 mA with a 50 kΩ input for positive-output sensors such as air gap and dynamic pressure. Each channel drives a +4 to +20 mA recorder output with 0.3662 µA per bit resolution and an update rate of 100 ms or less.
On the Bently Nevada 3500/46M, Alert setpoints can be placed on each active static value and Danger setpoints on any two of them. Multimode channels hold up to eight sets of alarm parameters, each linked to a machine mode such as spinning reserve, generating or pumping, and switch between them using contacts on the multimode I/O modules or commands through a communications gateway. Supported scale factors include 20, 100 or 200 mV/mil for radial vibration, 5, 5.6, 12.5 or 14 mV/mil for air gap, 100, 200 or 285 mV/mil for thrust, and 508 mV/(in/s) for hydro velocity.
Key Features
What the Bently Nevada 3500/46M can do, according to its datasheet:
- Four channels accepting proximity, air gap, velocity, acceleration and dynamic pressure sensors.
- Hydro Radial Vibration with 1X, NX and composite values for shear-pin failure detection.
- Air gap per pole with average, minimum and maximum gap and the matching pole numbers.
- Hydro Thrust and Hydro Acceleration channel types for axial position and casing vibration.
- Stator End Winding channel type for generator end winding vibration.
- Multimode channels with up to eight alarm sets selected by contacts or gateway commands.
- Radial vibration filtering suited to rotor speeds from 25 to 1,500 cpm.
- Buffered outputs and individual 4 to 20 mA recorder outputs on every channel.
Industrial Applications
The Bently Nevada 3500/46M is intended for hydro turbine-generator sets: Francis, Kaplan and Pelton units, bulb turbines and pumped-storage machines, where low running speeds, large air gaps and mode changes between generating, pumping and condensing make general-purpose vibration monitors a poor fit. Shear-pin detection protects the wicket gate linkage, air gap monitoring warns of rotor or stator distortion before rub, and multimode alarming avoids false alarms during start-up and mode transitions. Hydroelectric plants are uncommon in Oman itself, so enquiries for the Bently Nevada 3500/46M are more likely to come from engineering contractors, service companies and spare-parts buyers in the region supporting hydro units elsewhere, or from owners holding critical spares for installed racks.
A hydro protection rack usually combines the Bently Nevada 3500/46M with the Bently Nevada 3500/25 Keyphasor Module for the speed and phase reference, the 3500/32M 4-Channel Relay Module for alarm outputs, and the 3500/22M Transient Data Interface for data to diagnostic software. Seven Star LLC can source the Bently Nevada 3500/46M, matching I/O modules and termination hardware for customers in Oman and the GCC, and help confirm firmware and software revisions before installation.
Ordering Information
Order the Bently Nevada 3500/46M under code 3500/46-AA-BB using the options below:
| Option | Code | Description |
|---|---|---|
| A: I/O Module Type | 01 | Prox/Velom I/O Module with Internal Terminations |
| A: I/O Module Type | 02 | Prox/Velom I/O Module with External Terminations |
| A: I/O Module Type | 03 | Multimode Prox/Velom I/O Module with Internal Terminations |
| A: I/O Module Type | 04 | Multimode Prox/Velom I/O Module with External Terminations |
| A: I/O Module Type | 05 | Multimode Positive Input I/O Module with Internal Terminations |
| A: I/O Module Type | 06 | Multimode Positive Input 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) |
Hydro monitor spares and wiring hardware from the Bently Nevada 3500/46M datasheet:
| Part Number | Description |
|---|---|
| 176449-06 | 3500/46M Hydro Monitor |
| 140471-01 / 140482-01 | Prox/Velom I/O Module with Internal / External Terminations |
| 169459-01 / 169459-02 | Multimode Prox/Velom I/O Module with Internal / External Terminations |
| 169715-01 / 169715-02 | Multimode Positive Input I/O Module with Internal / External Terminations |
| 125808-08, 125808-11, 125808-12, 125808-13, 128702-01 | External termination blocks with Euro Style connectors for, in order: Prox/Velom; Multimode Prox/Velom; Multimode Positive Input; Multimode Recorder Output and Mode Input; Recorder |
| 128015-08, 128015-11, 128015-12, 128015-13, 128710-01 | The same five external termination blocks with Terminal Strip connectors |
| 129525-AAAA-BB | Transducer (XDCR) to ET block cable for the Bently Nevada 3500/46M: length code 0005 (5 ft) up to 0100 (100 ft), then 01 for a loose kit or 02 for factory assembly |
| 129529-AAAA-BB | Recorder output to ET block cable, non-multimode channels only, with the same length and assembly codes |
| 00561941 | Ten-pin connector shunt for Prox/Velom and Multimode Prox/Velom I/O modules |
| 00580434 / 00580432 | 8-pin and 10-pin Euro Style connector headers used on internal-termination I/O |
| 166M2389 / 166M2388 | Push-in-spring connector headers that can replace 00580434 and 00580432 |
| 144403-01 | 3500/46M Hydro Monitor User Guide |
Technical Specifications
Key Bently Nevada 3500/46M data from datasheet 144408 Rev. AD:
| Parameter | Specification |
|---|---|
| Model | Bently Nevada 3500/46M Hydro Monitor |
| Inputs | 1 to 4 proximity, air gap, velocity or acceleration sensor signals; dynamic pressure on multimode channels |
| Input impedance | Prox/Velom and Multimode Prox/Velom I/O: 10 kΩ prox/accel, 3.5 MΩ Velomitor; Multimode Positive Input I/O: 50 kΩ |
| Channel types | Hydro Radial Vibration, Air Gap, Velocity, Acceleration, Thrust, Stator End Winding; multimode RV, Air Gap, Velocity, Thrust, Acceleration, Dynamic Pressure |
| Radial vibration | Direct 0.104–500 Hz; rotor speed 25–1,500 cpm; NX selectable 2–20 (or 2–50 up to 600 cpm); composite value for shear-pin failure |
| Air gap | Average, minimum and maximum gap and pole numbers at 1 to 200 poles/s; instantaneous gap below 1 pole/s |
| Hydro velocity | Direct 0.1875–343.75 Hz (Low mode) or 0.75–1375 Hz (High mode); not for automated protection |
| Stator end winding | Direct 5.0–800 Hz, 100 mV/g accelerometers; pole pass amplitude |
| Transducer power | −23 Vdc at 43 mA max (Prox/Velom I/O); +23 Vdc at 23 mA max (Multimode Positive Input I/O) |
| 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 |
| Alarms | Alert on each active static value, Danger on any two; up to eight alarm sets on multimode channels |
| Power consumption | 7.7 W typical |
| Monitor / I/O module weight | 0.91 kg / 0.20 kg |
| Rack space | 1 full-height front slot; 1 full-height rear slot |
How to Order
To request a quotation for the Bently Nevada 3500/46M, send Seven Star LLC the full 3500/46-AA-BB order code, or the channel types, sensor models and scale factors, and whether multimode alarming or positive-input sensors are involved. Our team in Muscat will confirm availability and lead time for the monitor, I/O module and termination hardware, and the datasheet can be downloaded from the documents tab on this page. We supply the Bently Nevada 3500/46M to customers in Oman and the GCC.
- Datasheet Bently Nevada 3500/46M Hydro Monitor Datasheet (144408 Rev. AD) 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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