The BENTLY NEVADA 3500/42M 140734-02 Position & Seismic Monitor is a four-channel monitoring device specially designed for machinery protection and condition monitoring. As a member of the Bently Nevada 3500 product series, it is equipped with powerful functions for signal acquisition, processing, analysis and alarm.
This device is compatible with input signals from multiple types of sensors including proximity and seismic sensors. It can accurately monitor a variety of critical mechanical parameters such as radial vibration, thrust position, eccentricity, acceleration and velocity. By conducting real-time comparison with user-programmable alarm thresholds, it triggers timely alerts to prevent equipment failures. Meanwhile, it efficiently transmits core equipment information to operation and maintenance personnel, supporting real-time equipment condition monitoring and fault early warning. It is widely applicable to reliability assurance scenarios for various key mechanical equipment in industrial production. Its firmware and software must be used with specific versions of 3500 series software and corresponding module firmware to ensure stable system operation.
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Core Functions
Multi-parameter Monitoring Capability
After programming each channel via the 3500 Rack Configuration Software, this monitor enables diversified parameter monitoring and reporting, covering a variety of key metrics including radial vibration, REBAM (Rolling Element Bearing Analysis and Monitoring), thrust position, shaft absolute vibration, acceleration, differential expansion, eccentricity, circular acceptance zone, and velocity.
Monitoring channels are programmed in pairs, with each channel pair capable of executing up to two of the listed functions simultaneously. For example, channels 1 and 2 can perform one function, while channels 3 and 4 can execute the same or another function, flexibly adapting to different monitoring requirements.
Alarm and Protection Mechanism
Users can configure alarm thresholds for each activated static value (various monitoring parameters generated by input signal conditioning). Meanwhile, danger thresholds can be set for any two activated static values. Alarm thresholds are adjustable within the range of 0 to 100% of the full scale; however, if the full-scale range exceeds the sensor range, the sensor range will limit the threshold setting.
Alarm delays can be programmed via the Rack Configuration Software, with the adjustable range varying by channel type. For instance, for all channel pairs except shaft absolute velocity and REBAM, the alarm delay ranges from 1 to 60 seconds (1-second increments), and the danger delay is either 0.1 seconds or 1 to 60 seconds (0.5-second increments). For REBAM channels, the alarm delay is adjustable from the calculated minimum value to 400 seconds. This ensures the accuracy and flexibility of alarm responses, effectively protecting mechanical equipment.
Signal Communication and Output
The device is equipped with front-panel LED indicators: the OK light indicates the normal operation status of the device, the TX/RX light displays the communication status with other modules in the 3500 rack, and the Bypass light indicates whether the device is in bypass mode.
Each channel is provided with a coaxial connector serving as the buffered sensor output terminal, which features short-circuit protection with an output impedance of 550Ω. In addition, the device offers a +4 to +20mA recorder output, with the output value proportional to the full scale of the monitor. Each channel has an independent recorder value, and a short circuit of the recorder output will not affect the operation of the monitor. The voltage compliance range is 0 to +12Vdc (with a load resistance of 0 to 600Ω). The shaft absolute I/O module provides one output per channel group, which also has short-circuit protection with an output impedance of 300Ω.
Technical Specifications
Input Parameters
- Signal Input: Accepts 1 to 4 channels of proximity, velocity, or acceleration sensor signals.
- Power Consumption: Typical value: 7.7 W.
- Input Impedance: 10 kΩ for standard I/O (proximity and acceleration inputs).
- Sensitivity: Sensitivity varies by monitoring parameter, as detailed below:
- Radial vibration, thrust position, eccentricity, shaft absolute vibration (radial and direct measurement): 3.94 mV/μm (100 mV/mil) or 7.87 mV/μm (200 mV/mil).
- Differential expansion: 0.394 mV/μm (10 mV/mil) or 0.787 mV/μm (20 mV/mil).
- REBAM: 40 mV/μm (1000 mV/mil) or 80 mV/μm (2000 mV/mil).
- Acceleration and acceleration squared: 10 mV/(m/s²) (100 mV/g).
- Velocity and velocity squared: Three options available — 20 mV/(mm/s) pk (500 mV/(in/s) pk), 5.8 mV/(mm/s) pk (145 mV/(in/s) pk), and 4 mV/(mm/s) pk (100 mV/(in/s) pk).
Signal Conditioning Performance
Parameters related to signal conditioning are calibrated at +25°C (+77°F) by default, with specified frequency response and accuracy for different monitoring parameters:
- Radial Vibration:
- Direct filter: User-programmable single-pole, with -3 dB frequency range of 4 Hz to 4000 Hz or 1 Hz to 600 Hz (accuracy: ±1%).
- Gap filter: -3 dB frequency at 0.09 Hz.
- Non-1X filter: Constant-Q notch filter ranging from 60 cpm to 15.8× operating speed, with minimum stopband rejection of -34.9 dB.
- Accuracy of direct and gap filtering (excluding filtering): Typical value ±0.33% of full scale; maximum value ±1% of full scale.
- Accuracy of 1X and 2X vector filtering: Same as direct and gap filtering.
- Smax accuracy: Maximum ±5%.
- Non-1X filtering accuracy: ±3% at rotational speeds below 30,000 cpm; ±8.5% at speeds above 30,000 cpm.
- Acceleration:
- RMS unfiltered frequency range: 10 Hz to 30,000 Hz.
- RMS with low-pass or high-pass filtering: 10 Hz to 9,155 Hz.
- RMS with integration: 10 Hz to 9,155 Hz.
- Accuracy (excluding filtering): Typical value ±0.33% of full scale; maximum value ±1% of full scale.
- Equipped with 4-pole high-pass and low-pass filters (80 dB per decade, 24 dB per octave). Frequency response range varies by channel activation mode. For example, in dual-channel activation mode:
- Velocity and Velocity II:
- Accuracy (excluding filtering): Typical value ±0.33% of full scale; maximum value ±1% of full scale. Accuracy is +1%, -3% when paired with MTL 764 (-) Zener external barriers.
- Typical accuracy of Velocity sensors varies by full-scale range: ±3% at 0–0.5 full scale; ±2% at 0–1.0 full scale; ±1% at 0–2.0 full scale. Total accuracy across all full-scale ranges is ±15% when used with barriers under radiation immunity conditions.
- Frequency response: -3 dB frequency range for RMS is 10 Hz to 5,500 Hz; for peak or peak-to-peak values, it is 3 Hz to 5,500 Hz.
Environmental and Physical Characteristics
- Environmental Limits:
- Operating temperature: 0°C to +65°C (32°F to +150°F) when paired with internal/external terminal I/O modules and internal barrier I/O modules (internal terminals).
- Storage temperature: -40°C to +85°C (-40°F to +185°F).
- Relative humidity: 95% (non-condensing).
- Physical Dimensions and Weight:
- Monitor module (main board): 241.3 mm × 24.4 mm × 241.8 mm (9.50 in × 0.96 in × 9.52 in), weight: 0.91 kg (2.0 lb).
- Non-barrier I/O module: 241.3 mm × 24.4 mm × 99.1 mm (9.50 in × 0.96 in × 3.90 in), weight: 0.20 kg (0.44 lb).
- Barrier I/O module: 241.3 mm × 24.4 mm × 163.1 mm (9.50 in × 0.96 in × 6.42 in), weight: 0.46 kg (1.01 lb).
- Rack Space Requirements: The monitor occupies 1 full-height front slot, and the I/O module occupies 1 full-height rear slot.
Ordering and Accessory Information
Product Ordering Codes
The ordering code format of the monitor is 3500/42-AA-BB, where AA denotes the I/O module type, and BB represents the hazardous area certification option (00 = no certification, 01 = cNRTLus (Class 1, Division 2), 02 = ATEX / IECEx / CSA (Class 1, Zone 2)).
A wide range of I/O module types is available, including:
- Prox/Seismic I/O module with internal terminals (Model 128229-01)
- Prox/Seismic I/O module with external terminals (Model 128240-01)
- Various I/O modules with internal barriers
- Shaft absolute I/O module
- Prox/Velom I/O module
Different modules vary in the supported sensor types and terminal modes.
Accessories and Spare Parts
- External Terminal Blocks: Two models are offered:
- 125808-08 (Proximitor/Velomitor external terminal block, European-style connector)
- 128015-08 (Proximitor/Velomitor external terminal block, terminal strip connector)Note: External terminal blocks are not compatible with I/O modules equipped with internal terminals.
- Cables:
- 3500 sensor-to-external terminal block cable (Model 129525-AAAA-BB)
- External terminal block cable (Model 129529-AAAA-BB)Where AAAA indicates the cable length (options: 5 ft, 7 ft, 10 ft, 25 ft, 50 ft, 100 ft), and BB denotes the assembly status (01=unassembled, 02= assembled).
- Spare Parts: This category covers monitor main units (176449-02), various I/O modules, connector splitters, connector plugs, etc. Examples include:
- 3500/42M Prox/Seismic I/O module 4-pin connector splitter (00530843)
- Shaft absolute I/O module 8-pin connector splitter (00517018)In addition, refer to the 3500/05 system rack data sheet for spare front and rear cover plates.
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