Bently Nevada 134938-01 Tachometer Module

This tachometer module delivers accurate speed measurement for rotating machinery protection. It integrates seamlessly into the Bently Nevada 3500 monitoring system platform. The unit accepts signals from various speed transducers for comprehensive overspeed detection. Users can monitor turbines, compressors, and pumps with exceptional reliability.

Input Channel Configuration and Transducer Compatibility

This module features two independent input channels for speed transducer connectivity. It accepts magnetic pickups, proximity probes, and hall effect sensors for versatile installation. The unit also supports MPU (magnetic pickup) signals from 200 mV to 100 V peak. Each channel includes individual signal conditioning for optimal measurement accuracy. This flexibility accommodates diverse speed monitoring applications across industries.

Signal Processing and Speed Calculation

The 134938-01 processes input signals with exceptional precision and stability. It measures frequency using period-based or count-based methods for optimal accuracy. The module converts raw frequency data into RPM values for monitoring and alarming. Users can program the gear tooth count and scaling factors through software. This configuration ensures accurate speed representation for various machine types. Consequently, operators receive reliable speed data for critical machine protection.

Overspeed Detection and Alarm Management

This module supports configurable alarm and danger setpoints for overspeed protection. Users set high thresholds for warning and emergency shutdown conditions. The module activates outputs when speed exceeds configured limits. It also provides speed trend analysis for predictive maintenance insights. Additionally, the unit includes a separate overspeed detection circuit for safety-critical applications. This redundant design ensures reliable operation in the most demanding environments.

Zero Speed and Direction Detection

The module includes zero-speed detection for start-up and shutdown monitoring. It alerts operators when the machine drops below the minimum operating speed. The unit also supports direction detection for reversible machines like dual-drive pumps. Users can configure direction logic to prevent reverse-rotation damage. This feature suits marine propulsion and wind turbine applications. Consequently, engineers achieve comprehensive speed monitoring with a single module.

System Integration and Communication

This tachometer communicates with the 3500 rack through the dedicated backplane bus. It exchanges speed data with the rack interface module for system-wide monitoring. Users configure all parameters through the proprietary 3500 configuration software. The module stores settings in non-volatile memory for automatic reloading. Additionally, it supports Modbus communication for integration with plant DCS systems. This connectivity enables centralized monitoring and data logging capabilities.

Power Consumption and Environmental Specifications

The module draws 350 mA at 24 V DC from the 3500 rack power supply. Power dissipation remains below 5 W under normal operating conditions. The unit operates reliably between -10 °C and 65 °C ambient temperature. Humidity tolerance spans 0% to 90% without condensation issues. The module carries an IP20 rating for protection against solid objects. This robust design suits power generation, oil and gas, and heavy industrial applications.