Bently Nevada 3500/50 Tachometer Module

The Bently Nevada 3500/50 Tachometer Module is a 2-channel module that is designed to accept input from proximity probes or magnetic pickups to determine shaft rotative speed, rotor acceleration, or rotor direction. This information is then compared against user-programmable alarm setpoints, and generates alarms when these setpoints are violated. The 3500/50 Tachometer Module is programmed using the 3500 Rack Configuration Software and can be configured with four different options.

Speed Monitoring, Setpoint Alarming, and Speed Band Alarming

In this mode, the module monitors the shaft speed and alerts the user if the speed exceeds the setpoint or if the speed falls outside the specified speed band. This mode is particularly useful for applications where it is important to maintain a specific speed range.

Speed Monitoring, Setpoint Alarming, and Zero Speed Notification

In this mode, the module monitors the shaft speed and alerts the user if the speed drops to zero. This mode is useful for applications where it is important to ensure that the shaft is not stalled or stopped.

Speed Monitoring, Setpoint Alarming, and Rotor Acceleration Alarming

In this mode, the module monitors the rotor acceleration and alerts the user if the acceleration exceeds the setpoint. This mode is particularly useful for applications where it is important to ensure that the rotor is not being subjected to excessive acceleration.

Speed Monitoring, Setpoint Alarming, and Reverse Rotation Notification

In this mode, the module monitors the shaft rotation direction and alerts the user if the direction of rotation changes. This mode is particularly useful for applications where it is important to ensure that the rotor is not rotating in the wrong direction.

The 3500/50 Tachometer Module is also capable of supplying conditioned Keyphasor® signals to the backplane of the 3500 rack for use by other monitors, thus eliminating the need for a separate Keyphasor module in the rack. Additionally, the module has a peak hold feature that stores the highest speed, highest reverse speed, or number of reverse rotations (depending on channel type selected) that the machine has reached. These peak values can be reset by the user.

Notic

It is important to note that the Bently Nevada Tachometer Modules are not designed for use independently as, or as a component of, a speed control or overspeed protection system. They do not provide the protective redundancy or the response speed needed for reliable operation as a speed control or overspeed protection system. The analog proportional output, where provided, is suitable for data logging, chart recording, or display purposes only. The speed alert setpoints, where provided, are suitable for annunciation purposes only.

Magnetic pickups may not be used for the reverse rotation option because these transducers do not provide a clean edge for the detection circuit during low speeds. This could lead to false indications of rotation direction. Magnetic pickups are also not recommended for the zero speed option because these transducers do not provide a clean edge for the detection circuit during low speeds.

Conclusion

The Bently Nevada 3500/50 Tachometer Module is a versatile and reliable 2-channel module that provides crucial information regarding shaft rotative speed, rotor acceleration, and rotor direction. With its ability to generate alarms and supply conditioned Keyphasor® signals to the backplane of the 3500 rack, it is an essential tool for ensuring the proper operation of machinery.