Bently Nevada 3500/50 Tachometer Module

Overview

The Bently Nevada 3500/50 Tachometer Module provides precise shaft speed monitoring for critical rotating machinery. Moreover, it accepts signals from proximity probes or magnetic pickups to determine rotor speed, acceleration, and rotation direction. Consequently, it generates alarms whenever measurements exceed user-defined setpoints, ensuring rapid detection of abnormal operation.

The module integrates seamlessly with the 3500 Rack Configuration software, allowing users to configure speed monitoring, setpoint alarming, speed band alarming, zero-speed notifications, rotor acceleration alarming, and reverse rotation notifications. Furthermore, it can supply conditioned Keyphasor signals to the 3500 rack backplane, eliminating the need for a separate Keyphasor module.

Additionally, the peak hold feature stores maximum speed, reverse speed, and total reverse rotations, which users can reset when required. This capability helps operators track critical machine performance trends efficiently.

Key Features

Dual Channel Input: Accepts two transducer signals from proximity probes or magnetic pickups.
Configurable Alarms: Supports speed, zero-speed, rotor acceleration, reverse rotation, and speed band alarms.
Keyphasor Output: Supplies conditioned signals directly to the 3500 rack backplane for use by other monitors.
Peak Hold Capability: Stores highest speed and reverse speed values for operator review.
Recorder Output: Provides +4 to +20 mA signals proportional to module full-scale range.
Protected Outputs: Coaxial connectors on the front panel are short-circuit and ESD protected.
Flexible Power Supply: 24 Vdc, 40 mA maximum per channel for transducer operation.

Technical Specifications

Specification	Detail
Model Number	3500/50
Manufacturer	Bently Nevada
Product Type	Tachometer Module
Input Signal	+10 V to -24 V from proximity probes or magnetic pickups
Input Impedance	20 kΩ standard, 40 kΩ TMR, 7.15 kΩ buffered transducer
Outputs	Front coaxial connectors per channel, buffered I/O via Euro connectors
Output Impedance	550 Ω
Transducer Power Supply	24 Vdc, 40 mA max per channel
Recorder Output	+4 to +20 mA, proportional to full-scale range (rpm or rpm/min)
Voltage Compliance	0 to +12 Vdc across 0–600 Ω load
Resolution	0.3662 µA per bit, ±0.25% error at room temperature
Update Rate	Approximately 100 ms per measurement

Applications

The Bently Nevada 3500/50 module actively monitors machinery rotation, therefore enabling predictive maintenance strategies. Furthermore, it supports high-reliability alarm generation and rotor performance tracking, critical in turbines, compressors, and other industrial rotating equipment. Additionally, integration with the 3500 rack simplifies system architecture by reducing the need for additional Keyphasor modules.