Description
Bently Nevada 126398-01
Technical Specifications
- Module Type: Enhanced Keyphasor Monitor
- Channels: Two channels per half-height module
- Input Types: Proximity probes, magnetic pickups, accelerometers
- Input Impedance: 50 kΩ on standard inputs
- Output Impedance: 50 Ω maximum buffered output
- Buffered Output: Coaxial connectors, short-circuit protected
- Phase Accuracy: High precision maintained across speed range
- Power Consumption: 3.2 watts typical
- Operating Temperature: -30°C to +65°C for standard I/O, 0°C to +65°C for internal barrier I/O
- Storage Temperature: -40°C to +85°C
- Humidity: 95% non-condensing
- Dimensions: 11.99 cm height x 2.44 cm width x 25.65 cm depth
Functional Features
- High-precision phase reference generation
- Buffered transducer outputs for each channel
- Compatibility with multiple transducer types
- Support for redundant keyphasor configurations
- Front panel LEDs indicating OK and communication status
- Direct plug-in replacement capability for earlier keyphasor modules
- Rack-wide pulse distribution to other monitoring modules
Application Scenarios
- Phase-locked vibration analysis on turbines and compressors
- Speed verification for overspeed protection systems
- Rotor balancing reference signal generation
- Torsional vibration studies
- Order tracking and synchronous time averaging
- Machine train timing and synchronization
Performance Parameters
- Accurate phase measurement from very low to very high speeds
- Low jitter on keyphasor pulse output
- Stable pulse amplitude independent of input signal variation
- High noise immunity on magnetic pickup channels
- Reliable operation in electrically noisy industrial environments
Material Composition
- Faceplate: Aluminum with printed legends
- Circuit card: Multi-layer FR4 with conformal coating
- Connectors: Gold-plated coaxial and card-edge contacts
- Integrated circuits: Industrial-grade timing and logic devices
Structural Characteristics
- Half-height 3500 series module format
- Front panel BNC connectors for buffered outputs
- Rear card edge for I/O module interconnection
- LED indicators visible through front panel
- Secure latching mechanism for vibration resistance
Working Principle The module receives an analog signal from a proximity probe or magnetic pickup sensing a once-per-revolution mark on the rotating shaft. An internal comparator with adjustable threshold converts the analog waveform into a precise digital pulse occurring at the exact angular position of the mark. This pulse, known as the keyphasor event, is output on buffered connectors and distributed across the 3500 rack backplane. Other monitors use this pulse to establish phase references for orbit plots, spectrum analysis, and speed calculation.
Installation Requirements
- Install in a 3500 rack slot with matching I/O module directly behind
- Configure probe type and threshold voltage through rack software
- Magnetic pickup applications require isolated I/O modules
- Ensure proper shield grounding for noise-sensitive installations
- Firmware must meet minimum revision requirements for full functionality
Usage Precautions
- Verify keyphasor pulse quality on an oscilloscope during commissioning
- Ensure the once-per-revolution target is clean and undamaged
- Do not overload buffered outputs with low-impedance loads
- Multiple keyphasor modules require proper rack configuration to avoid conflicts
- Maintain spare modules for critical applications where phase data is essential
