The Bently Nevada 3500/50M, part of the industry-standard 3500 Series Machinery Protection System, is a high-performance tachometer module designed for critical machinery speed monitoring. Engineered by Baker Hughes (formerly GE Bently Nevada), the 3500/50M provides continuous, highly accurate measurements of rotational speed, acceleration, and direction. It serves as a vital safety and diagnostic tool, allowing operators to monitor machine health and trigger automatic shutdowns in the event of overspeed or underspeed conditions.

Technical Description & Parameters

The 3500/50M is a two-channel module that accepts inputs from various proximity and magnetic sensors to calculate precise speed data.

• Model Number: 3500/50M (286566-02 or 133442-01)
• Module Type: Tachometer / Speed Monitor
• Channels: 2 Independent Speed Channels
• Input Types: Proximitor* Sensors, Magnetic Pickups, or Rotary Encoders.
• Frequency Range: 0.017 Hz to 50 kHz (approx. 1 RPM to 99,999 RPM).
• Accuracy: ±1 RPM for most speed ranges.
• Outputs: 4-20mA proportional outputs and buffered transducer signals.
• Alarm Types: Overspeed, Underspeed, Zero Speed, and Acceleration.
• Mounting: Standard 3500 Full-Size Rack (Requires an Internal or External Termination I/O Module).

 

Product Technical Description

The 3500/50M processes pulses from a notched shaft or gear (Keyphasor* signal) to determine rotational velocity. Unlike standard I/O modules, the “M” designation (M-series) indicates enhanced digital signal processing capabilities, allowing it to provide conditioned “Buffered” signals to external diagnostic equipment like the System 1* software. It supports “Speed Event” capturing, which records the exact speed and timestamp of trip events, providing essential data for root cause analysis after a machine shutdown.

 

Product Datasheet Essentials

This module features an integrated “Peak Speed” memory that stores the highest RPM reached since the last reset. It is designed with redundant power input paths from the 3500 rack backplane, ensuring zero downtime if one power supply fails. The 3500/50M is SIL (Safety Integrity Level) rated, making it suitable for use in emergency shutdown (ESD) loops. It includes front-panel LEDs for “OK,” “TX/RX” (Communication), and “Bypass” status, providing immediate local diagnostics.

 

Country of Origin

USA (Bently Nevada / Baker Hughes)

 

Application Fields

The 3500/50M is found in high-stakes rotating machinery across the globe:

• Oil & Gas: Monitoring large steam and gas turbines in refineries.
• Power Generation: Speed and overspeed protection for utility-grade generators.
• Chemical Processing: Tracking centrifugal compressor speeds.
• Marine Engineering: Monitoring propulsion shaft RPM on large vessels.

 

Product Usage Instructions

1. Installation: Insert the 3500/50M into any available slot in the 3500 rack (excluding the Power Supply and RIM slots). Secure the module using the top and bottom screws.
2. Transducer Connection: Connect the Keyphasor* or Proximitor* sensor leads to the corresponding I/O module on the rear of the rack.
3. Configuration: Use the 3500 Rack Configuration Software to set the number of “Events per Revolution” (e.g., the number of teeth on the gear) and the alarm set-points (Overspeed/Underspeed).
4. Verification: Use a function generator to simulate a pulse frequency and verify that the 3500/50M displays the correct RPM on the software console.
5. Bypass Mode: Use the front-panel bypass switch (if configured) during maintenance to prevent accidental machine trips while testing sensor signals.

 

Common Questions & Answers (Q&A)

Q: What is the difference between the 3500/50 and the 3500/50M? A: The “M” version (M-series) is the modern, enhanced version that provides better integration with Bently Nevada’s System 1* diagnostic platform and features improved internal processing for higher frequency inputs.

Q: Can one 3500/50M monitor two different shafts? A: Yes. The module has two independent channels, allowing you to monitor two separate machines or two different points on a single powertrain, provided they share the same rack.

Q: How do I handle a “Not OK” LED status? A: A “Not OK” status usually indicates a problem with the transducer (sensor) or the field wiring. Check the gap of the proximity probe and verify the voltage levels at the I/O module terminals.

 

Explore More Machinery Protection Modules

For technical support and to source the 3500/50M along with other Bently Nevada 3500 spare parts, visit our specialized technical catalog.

 

Recommended Similar Models

1. 3500/25 – The Keyphasor* Module, used as a reference for phase and speed.
2. 3500/42M – Proximitor* / Seismic Monitor for vibration analysis.
3. 3500/40M – Proximitor* Monitor for displacement and position.
4. 3500/53 – Electronic Overspeed Detection System (for high-SIL requirements).
5. 3500/15 – The 3500 System Power Supply module.