Bently Nevada 3500/25 Enhanced Keyphasor Module

Comprehensive Technical Specifications

Functional Overview and Speed Sensing

This module provides precise rotational speed and phase reference signals for the 3500 Series system. It processes pulses from various transducers to generate a once-per-turn Keyphasor signal. The 3500/25 then delivers this timing reference to other modules in the rack. For instance, the monitor modules use this signal for synchronous vibration measurements. The module also outputs a buffered representation of the raw transducer signal. This buffered output enables technicians to verify transducer health easily. Furthermore, the module supports both proximity probe and magnetic pickup inputs.

Advanced Triggering and Signal Conditioning

The Bently Nevada 3500/25 features independently adjustable trigger levels for each input channel. You can set these thresholds to accommodate different transducer types and installation gaps. The module includes automatic trigger level tracking for proximity probes. This feature compensates for slow gap voltage drift due to thermal expansion. Additionally, the module incorporates hysteresis to prevent false triggering from electrical noise. The enhanced design also provides improved low-speed performance down to 1 RPM. Therefore, the module suits both startup and normal operating speed measurements.

Mechanical Architecture and Connectivity

The module fits into a single slot within the 3500 chassis frame. Its slim 25 mm width maximizes space for additional monitoring modules. The 241 mm height ensures proper alignment with rack guide rails. The 200 mm depth also allows ample room for rear cable management. Combined, the module dimensions (W x H x D) measure 25 mm x 241 mm x 200 mm (1.0″ x 9.5″ x 7.9″) . The 20-pin ARINC front connector provides a robust, vibration-resistant interface. This connector securely locks to prevent accidental disconnection. The rear backplane connector distributes power and shares the Keyphasor signal across the rack. The internal 47 µF capacitor bank provides ride-through capability during brief power disturbances.

Input Flexibility and System Integration

The module accepts two independent transducer inputs simultaneously. Each channel operates with its own trigger threshold and hysteresis settings. Consequently, you can monitor two separate speed sources on a single machine. Typical applications include steam turbines, gas turbines, and large centrifugal compressors. The module outputs a digital pulse train on the backplane. All 3500 Series monitor modules then receive this synchronized timing reference. The front panel LEDs indicate the presence of valid trigger pulses. These visual indicators simplify troubleshooting during commissioning and maintenance.

Operational Environment and Standards

The module operates across a 0°C to +65°C ambient temperature range. Storage temperatures range from -40°C to +85°C. The unit also complies with CE and RoHS directives. Install the module in a clean, low-humidity control cabinet. The module performs self-test routines at power-up. Regular verification every 12 months maintains measurement accuracy.