Description
Providing critical rotational velocity and acceleration data for machinery protection, the Bently Nevada 3500/50-01-CN functions as a high-precision, four-channel tachometer module within the 3500 Machinery Protection System. This configuration processes input signals from proximity probes or magnetic pickups to evaluate shaft rotational speed, rotor acceleration, and direction of rotation. Configured with the 01 I/O module type, this unit incorporates internal terminations to simplify cabinet integration. The CN suffix designates country-specific regulatory approvals, ensuring compliance with specialized regional hazardous area certifications.
Features
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Four Independent Channels: Delivers concurrent speed, peak speed, and phase measurement diagnostics across up to four transducer inputs.
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Internal Terminations (01 Option): Facilitates direct field wiring connections without requiring external termination blocks or specialized interface cables.
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Flexible Transducer Compatibility: Directly interfaces with passive magnetic pickups, proximity transducer systems, and active speed sensors.
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Advanced Alarm Tracking: Supports overspeed, underspeed, and zero-speed alert configurations with user-programmable delay parameters.
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Robust System Integration: Fully compatible with the standard 3500 rack mainframe, communicating diagnostics directly to the rack backplane.
Applications
- Steam turbine overspeed protection and operational RPM monitoring.
- Centrifugal compressor and expander speed-tracking loops.
- Large industrial electric motor and generator shaft diagnostics.
- Hydroelectric turbine runner speed and phase angle verification.
Technical Specifications
| Parameter |
Specification Values |
| Manufacturer |
Bently Nevada (Baker Hughes) |
| Model Number |
3500/50-01-CN |
| Module Type |
Tachometer Module (4-Channel) |
| I/O Module Option |
01 (Internal Terminations) |
| Agency Approvals Option |
CN (Country Specific / China Regional Approvals) |
| Signal Inputs |
Magnetic Pickups, Proximity Transducers (3-wire) |
| Input Frequency Range |
0.0015 Hz to 50,000 Hz |
| Operating Temperature |
-30 degC to 65 degC |
| Storage Temperature |
-40 degC to 85 degC |
| Country of Origin |
United States (U.S.A.) |
| Shipping Weight (Calculated) |
3.00 kg (6.61 lbs) |
Connections and Interfaces
| Terminal Connection Block |
Signal Assignment / Function |
| Ch 1 (SIG / COM / VT) |
Speed Sensor / Transducer Input Channel 1 |
| Ch 2 (SIG / COM / VT) |
Speed Sensor / Transducer Input Channel 2 |
| Ch 3 (SIG / COM / VT) |
Speed Sensor / Transducer Input Channel 3 |
| Ch 4 (SIG / COM / VT) |
Speed Sensor / Transducer Input Channel 4 |
| SHIELD Terminals |
Instrumentation Shield Earth Ground Points |
Alternative Models & Compatibility
The 3500/50-01-CN module with internal terminations acts as a direct replacement for configurations operating with the 3500/50-02 external termination structures, provided field wiring is adapted directly to the cabinet panel. When migrating from legacy firmware, confirm that the 3500 Rack Configuration Software is updated to support the CN regulatory profiles to prevent system configuration validation errors during rack download procedures.
Application Pitfalls & Engineering Notes
When utilizing passive magnetic pickups, check that the shaft surface velocity and sensor-to-target gap generate sufficient voltage amplitudes (typically > 1V peak-to-peak) at lowest operating speeds. Failure to verify this parameter can result in missing pulses and subsequent under-speed alarms during cold startup sequences. For systems requiring active 3-wire proximity probes, avoid routing speed signal cabling alongside high-power motor lines to prevent high-frequency noise injection from compromising the phase indicators.
Commissioning & Wiring Tips
Ensure sensor shield drain wires are terminated strictly to the SHIELD pins on the 3500/50-01-CN I/O module. Do not ground the shield at both ends; doing so establishes a ground loop that introduces electromagnetic interference onto the high-frequency speed pulse stream. When configuring the software, accurately input the number of teeth on the multi-tooth speed target to ensure correct scaling of the output RPM values.
Installation Guidelines
CRITICAL WARNING:
Prior to inserting or removing the tachometer module, verify that the 3500 rack power supply is completely de-energized. Removing modules under power ("hot-swapping") in classified hazardous areas represents a severe ignition hazard. Always confirm local atmospheric safety certifications before executing maintenance actions on the control cabinet.
1
Slide the main tachometer module into the front slot of the 3500 chassis, ensuring proper alignment with the backplane connectors.
2
Secure the front-panel captive retention screws to ensure the module frame achieves stable chassis ground connection.
3
Locate the matching slot on the rear of the rack and insert the 3500/50-01-CN internal termination I/O module.
4
Securely tighten the rear I/O module retention fasteners before connecting transducer cabling to the integrated screw terminal blocks.