The Bently Nevada 3500/50M Tachometer Module is a 2-channel monitor designed for speed measurement in rotating machinery protection systems. It accepts input from proximity probes or magnetic pickups to determine shaft rotative speed, rotor acceleration, and direction of rotation.

The module compares measurements against user-programmable alarm setpoints. Four configuration options are available: speed monitoring with setpoint alarming and speed band alarming; zero speed notification; rotor acceleration alarming; and reverse rotation notification.

The 3500/50M provides conditioned Keyphasor signals to the rack backplane for use by other monitors, eliminating the need for a separate Keyphasor module. Peak hold function stores the highest speed, highest reverse speed, or number of reverse rotations reached; peak values can be reset by the operator.

Input signal range is +10.0 V to -24.0 V with selectable input impedance: 20 kΩ (standard), 40 kΩ (TMR), or 7.15 kΩ (internal barrier). Accuracy is ±0.01% FS. Power consumption is 5.8 watts typical. Operating temperature range is -40°C to +70°C.

Typical applications include turbine, compressor, and pump monitoring in power generation, oil and gas, and industrial automation.

Features

• 2-channel module accepts proximity probe or magnetic pickup inputs
• Measures shaft speed, rotor acceleration, and rotation direction
• Four field-configurable monitoring modes
• Programmable alarm setpoints
• Peak hold function stores highest speed, reverse speed, or reverse count
• Supplies conditioned Keyphasor signals to rack backplane
• Input signal range: +10.0 V to -24.0 V
• Selectable input impedance: 20 kΩ, 40 kΩ, or 7.15 kΩ
• Accuracy: ±0.01% FS
• Power consumption: 5.8 W typical
• Operating temperature: -40°C to +70°C
• Front panel status LEDs: OK, TX/RX, Bypass
• Multiple I/O module options including TMR and internal barrier