The Rotoguard III is a switch device for sensing the reduction, increase or loss in rotational motion for many types of moving equipment. The unit can detect changes in motion between 1 and 400 RPM depending on the model selected. The Rotoguard III may be direct coupled or driven through belts and chains. There are three basic models from which to choose. The Zero Speed unit offers no calibration where shaft alarm speeds are near zero RPM. The Adjustable Alarm Speed model offers economy where an alarm is needed with a 15% or greater change in speed. The Digital Set Alarm Speed offers precise and easy adjustment for alarms with as small as a 3% change in operating speed.


The unit has been designed to provide an alarm when a change in operating speed occurs. Rotoguard III sensors have an optical encoder and multi-toothed interrupter wheel to transform the rotation of the input shaft to voltage pulses. A change in input speed from the calibrated normal speed results in the output relay changing state. All models have a startup alarm delay feature which allows time for the monitored equipment to come up to speed before the Rotoguard III output alarms.

This unit is available in two enclosure types: a NEMA 4/5 Weather and Dust Proof, and a NEMA 7/9 Explosion Proof. Both are UL listed. (Please Note: Input speed must not exceed 100 RPM on a NEMA 7/9 Explosion Proof switch.)

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