3500_25_125792-01_bently_nevada_enhanced_keyphasor_module

Brand Bently Nevada

Model 3500_25_125792-01_bently_nevada_enhanced_keyphasor_module

Product Overview

The 3500/25 125792-01 is a Bently Nevada Enhanced Keyphasor Module designed for the 3500 Machinery Protection System. As a half-height, dual-channel module, the 3500/25 125792-01 provides the critical timing reference that enables vibration monitors to measure shaft rotative speed, 1X vibration amplitude, and phase. The module receives signals from proximity probes or magnetic pickups and converts them into precise digital Keyphasor pulses, which indicate when the Keyphasor mark on the shaft coincides with the transducer .

Within the 3500 architecture, the 3500/25 125792-01 acts as the synchronization heartbeat for the entire rack. A Keyphasor signal is a once-per-turn pulse from a rotating shaft, allowing monitor modules and diagnostic equipment to calculate vector parameters essential for detecting unbalance, misalignment, and bearing wear before they escalate into unplanned downtime . The module supports up to two transducer signals, and a standard 3500 configuration can accept up to four Keyphasor signals, expandable to eight in paired configurations .

The 3500/25 125792-01 is a legacy PWA module that has been completely superseded by the updated 149369-01 model. The newer module maintains complete downward compatibility in form, fit, and function, allowing direct replacement in existing 3500 racks without backplane or software modifications . Facilities maintaining legacy 3500 systems rely on the 3500/25 125792-01 as a sustainment solution to preserve validated machinery protection configurations.

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Description

Technical Specifications

Parameter Name	Parameter Value
Product Model	3500/25 125792-01
Manufacturer	Bently Nevada (GE)
Product Type	Enhanced Keyphasor Module
Compatible System	3500 Machinery Protection System
Input Channels	2 (half-height module)
Input Signal Range	+0.8 V to –21.0 V (Non-Isolated I/O); +5 V to –11 V (Isolated I/O)
Input Impedance	21.8 kΩ minimum
Speed/Frequency Range	1 to 1,200,000 cpm (0.017 Hz to 20 kHz)
Processed Output Range	1 to 99,999 cpm (0.017 to 1667 Hz)
Power Consumption	3.2 W typical
Buffered Output Impedance	504 Ω maximum
Keyphasor Power Supply	–24 VDC, 40 mA maximum per channel
Operating Temperature	–30°C to +65°C (non-barrier); 0°C to +65°C (internal barrier)
Storage Temperature	–40°C to +85°C
Main Module Dimensions	119.9 mm × 24.4 mm × 256.5 mm
Main Module Weight	0.34 kg
I/O Module Weight	0.46 kg
Rack Space	1 half-height front slot; 1 full-height rear slot

Main Features and Advantages

Precise shaft timing reference: The 3500/25 125792-01 converts analog signals from proximity probes or magnetic pickups into digital Keyphasor pulses, providing the once-per-turn or multiple-event-per-turn reference required for accurate speed and phase measurement. This timing accuracy is the foundation for 1X vibration vector calculations, rotor balancing procedures, and transient event analysis across the 3500 monitoring system .

Dual-channel half-height architecture: The 3500/25 125792-01 packs two independent Keyphasor input channels into a half-height module, maximizing rack efficiency. A standard 3500 system can process up to four Keyphasor signals with this configuration, while paired module configurations expand capacity to eight signals for complex or redundant monitoring requirements .

TMR and paired configuration support: For Triple Modular Redundant applications requiring maximum availability, two 3500/25 125792-01 modules can operate in parallel, providing primary and secondary Keyphasor signals to other modules in the rack. Paired configurations accommodate systems requiring more than four Keyphasor inputs without sacrificing redundancy .

Seamless legacy compatibility: The 3500/25 125792-01 maintains complete downward compatibility with existing 3500 racks. When replacement is required, the newer 149369-01 module can be inserted directly without altering backplane connections or system configuration. This drop-in compatibility preserves validated protection schemes and minimizes maintenance downtime .

Enhanced signal processing: The Enhanced Keyphasor design offers expanded capabilities over previous Keyphasor modules, including generation of once-per-turn event signals from multi-event-per-turn inputs and field-upgradeable firmware. Auto-threshold and manual threshold