Description

The Bently Nevada 3500/25 149369-01 is an Enhanced Keyphasor Module designed for the 3500 Machinery Protection System. This half-height, two-channel module provides essential Keyphasor signals to monitor modules within a 3500 rack. By receiving input signals from proximity probes or magnetic pickups, the module converts them into digital Keyphasor signals that indicate the precise moment a shaft mark coincides with the transducer. This updated module (149369-01) replaces the legacy PWA 125792-01, offering improved signal processing while maintaining full downward compatibility in form, fit, and function.

Features

• Half-height module design for efficient rack space utilization.
• Two independent input channels.
• Supports inputs from proximity probes or magnetic pickups.
• Generates once-per-turn event signals from multi-event-per-turn inputs.
• Supports field-upgradeable firmware and asset management data reporting.
• Supports up to four Keyphasor signals in normal configuration and up to eight in paired configurations.
• Compatible with Triple Modular Redundant (TMR) applications using parallel module operation.

Applications

• Steam and Gas Turbines: Monitoring speed, phase, thermal growth, and unbalance.
• Aeroderivative Gas Turbines: Casing and high-speed core shaft vibration monitoring.
• Hydroelectric Turbines: Rotor speed and air gap monitoring.
• Centrifugal Compressors: Speed variation detection and automated shutdown for bearing failure.
• Reciprocating Compressors: Rod position, pressure, and impulse monitoring for wear detection.
• Critical Pumps: Reverse rotation and zero-speed detection.

Technical Specifications

Installation Guidelines

• Ensure the 3500 rack power is disconnected before inserting or removing the module.
• The module occupies one half-height front slot; ensure the corresponding I/O module is installed in the rear slot.
• Field wiring for proximity probes or magnetic pickups connects to the rear I/O module terminal blocks.
• For External Terminations (ET), use only approved Bently Nevada cables to connect the I/O module to the ET block.
• Use isolated I/O modules when signals are shared between multiple devices to prevent electrical interference.
• Maintain proper ESD precautions during handling to protect sensitive internal circuitry.

FAQ

What is the primary function of the 3500/25?
It detects the Keyphasor mark on a rotating shaft to provide precise timing signals required for measuring shaft speed, 1X vibration amplitude, and phase.

Can this module be used in TMR configurations?
Yes, the 3500/25 supports TMR applications by using two modules in parallel to provide primary and secondary signals to the rack.

Does this module replace older versions?
Yes, the 149369-01 is the updated version that completely replaces the legacy PWA 125792-01 module.