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Description
The 3500/50 Tachometer Module is a 2-channel module that accepts input from proximity probes or magnetic pickups (except as noted) to determine shaft rotative speed, rotor acceleration, or rotor direction, compares these measurements 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:

1. Speed Monitoring, Setpoint Alarming, and Speed Band Alarming.
2. Speed Monitoring, Setpoint Alarming, and Zero Speed Notification.
3. Speed Monitoring, Setpoint Alarming, and Rotor Acceleration Alarming.
4. Speed Monitoring, Setpoint Alarming, and Reverse Rotation Notification.

The 3500/50 can be configured to supply 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. The 3500/50 also 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.

Application Note
Bently Nevada
Tachometer Modules are not designed for use independently as, or as a component
of, a speed control or overspeed protection system. Bently Nevada Tachometer Modules do not provide protective redundancy nor the response speed needed for reliable operation as a speed control or overspeed protection system. Where provided, the analog proportional output is suitable for data logging, chart recording, or display purposes only. Also, where provided, speed alert setpoints 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 not recommended for the zero speed option because these transducers do not provide a clean edge for the detection circuit during low speeds.

Failure to take the above items into account constitutes a misuse of the product and may result in
property damage and/or bodily injury. Note: The Bently Nevada product line does supply an Overspeed Protection System for the 3500 System. Consult Specification and Ordering Information part number 141539-01.

Ordering Information
Tachometer Module
3500/50-AXX-BXX-CXX

A: I/O Module Type
0 1 I/O Module with Internal Terminations
0 2 I/O Module with External Terminations
0 3 TMR I/O Module with External Terminations
0 4 I/O Module with Internal Barriers and Internal Terminations.

B: Agency Approval Option
0 0 None
0 1 CSA/NRTL/C
0 2 ATEX/CSA (Class 1, Zone 2)

C: Monitor Use
0 1 Speed Measurement
0 2 Reverse Rotation

Note: Agency Approval Option B 02 is only available with Ordering Option A 04.

Spares

288062-02 3500/50M Tachometer Module

133388-02 3500/50 Tachometer Module
133442-01 I/O Module with Internal Terminations
136703-01 Discrete Internal Barrier I/O Module with Internal Terminations
133434-01 I/O Module with External Terminations
133450-01 TMR I/O Module with External Terminations

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