Product Brief: Bently Nevada 3500/42-01-01 (4-Channel Proximitor/Seismic Monitor)
The 3500/42-01-01 is a 4-channel Proximitor/Seismic Monitor within the Bently Nevada 3500 series machinery protection system. The configuration code -01-01 indicates a standard version that accepts both eddy current proximity probes (Proximitor) and seismic transducers (accelerometers or velocity sensors). This dual-input capability makes it one of the most versatile monitors in the 3500 series, used for radial vibration, axial (thrust) position, casing vibration, and shaft relative vibration measurements.
Each channel can be independently configured for either proximity probe input or seismic input, allowing mixed monitoring strategies within a single module.
Key Features
4 independent input channels – each configurable as Proximitor or Seismic.
Accepts Bently Nevada Proximitor sensors (3300, 3300 XL, 7200 series) for shaft relative motion.
Accepts accelerometers (IEPE) or velocity transducers for casing/absolute vibration.
Programmable for radial vibration, axial position, eccentricity, or casing acceleration/velocity.
Provides Keyphasor tracking output to backplane for synchronous analysis.
Configurable scaling, alarm setpoints (Alert/Danger), and time delays.
Requires external relay module (3500/32) for physical alarm/trip outputs.
Parameters (Table)
| Parameter | Specification |
|---|---|
| Model | 3500/42 |
| Configuration Code | 3500/42-01-01 (Standard 4-channel Proximitor/Seismic Monitor) |
| Product Type | 4-channel dual-input monitor (Proximitor + Seismic) |
| Dimensions (Height x Width x Depth) | 241 mm x 25 mm x 242 mm (9.5 in x 1.0 in x 9.5 in) – occupies one slot in 3500 rack |
| Weight (approx.) | 0.9 kg (2.0 lb) |
| Number of Input Channels | 4 independent channels |
| Input Type (per channel) | Field-selectable: Proximitor OR Seismic |
| Proximitor Input Signal | -0.8 VDC to -22 VDC (Bently Nevada 3300/3300 XL/7200 series) |
| Seismic Input Signal | IEPE accelerometer (2–20 mA constant current) or velocity coil (±5 to ±24 V) |
| Measurement Types (Proximitor) | Radial vibration (µm pk-pk, mils pk-pk), axial position (Vdc, mm, mils), eccentricity |
| Measurement Types (Seismic) | Acceleration (g pk, m/s² pk), Velocity (mm/s pk, in/s pk) |
| Frequency Response (Proximitor) | 0 to 10 kHz (-3 dB) |
| Frequency Response (Seismic) | 0.5 Hz to 10 kHz (depends on sensor) |
| Accuracy | ±0.5% of full scale (Proximitor); ±1% of full scale (Seismic) |
| Dynamic Range | 80 dB (typical) |
| Alarm Outputs | 2 per channel (Alert & Danger) – requires 3500/32 relay module |
| Backplane Outputs | Buffered raw signal (BUF), Keyphasor tracking, processed data |
| Communication | Via 3500 rack interface (3500/20, 3500/22) to DCS/PLC/SCADA |
| Operating Temperature | -30°C to +65°C (-22°F to +149°F) |
| Storage Temperature | -40°C to +85°C (-40°F to +185°F) |
| Power Consumption | 6.5 W (typical from rack backplane) |
Application Scenarios (use cases)
| Application Area | Description |
|---|---|
| Steam Turbine (Shaft + Casing Vib) | Channels 1&2: shaft relative vibration (proximity probes at bearings); Channels 3&4: casing vibration (seismic) on bearing housings. |
| Gas Turbine Compressor Train | Proximity probes on high-speed shaft for radial vibration; seismic on gearbox casing to detect bearing degradation. |
| Centrifugal Compressor (Oil & Gas) | Mixed configuration: thrust position (proximitor) + casing vibration (seismic) in one module, saving rack space. |
| Generator Monitoring | Proximity probes for rotor vibration; seismic on stator core or bearing pedestals for structural resonance detection. |
| Large Induction Motor | Seismic sensors on motor frame (velocity) for imbalance/looseness; proximity probes on sleeve bearings (if available). |
| Hydro Turbine | Low-frequency seismic accelerometers for runner/housing vibration; proximity probes for shaft runout (slow speed). |
| Turboexpander / LNG Plant | Seismic on expander casing + proximity on thrust bearing – both in one monitor, ideal for compact racks. |
| Pump & Fan Trains (Critical) | Seismic sensors for bearing housing velocity (ISO 10816-3 compliance) mixed with proximity on overhung impeller shaft. |
Notes
3500/42-01-01 is the fully configurable version – each channel can be independently set to Proximitor or Seismic via configuration software.
For pure seismic applications (no proximity probes), use same module and leave unused channels disabled or set to seismic.
For pure proximity applications (4-channel Proximitor only), the 3500/42-04-01 is the dedicated version (no seismic capability).
Requires field termination module (e.g., 3500/42M for proximity + seismic combined or separate 3500/42 terminal block) – sold separately.
Keyphasor reference must be provided by a 3500/25 Keyphasor Module elsewhere in the rack for synchronous measurements.
This module is not intrinsically safe – for hazardous area probe connections, use 3500/42M 140482-01 (with internal IS barriers).
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