DAZIC® RotoGuard® III

RotoGuard® III Speed Switches

The RotoGuard® III is an electronic speed switch device for sensing the reduction, increase, or loss in rotational motion associated with many types of moving equipment. The unit can detect changes in motion between 1 and 400 RPM, depending on the model selected, and provide a change of state, or alarm, when a variation in operating speed occurs. The RotoGuard® III may be direct coupled to another shaft or driven with a belt or chain.

Three models to fit your application:

  • Zero Speed

    Actuates an alarm when the shaft speed drops below 1 RPM. Not field-adjustable.

  • Adjustable Alarm Speed

    Ideal for applications where an alarm is needed with a 15% or greater change in rotational speed.

  • Digital Set Alarm Speed

    Easy and precise alarm adjustment with as small as a 3% change in operating speed.

The RotoGuard® III is designed with an optical encoder and multi-toothed interrupter wheel to transform the rotation of the input shaft to voltage pulses. A change of input speed from the calibrated normal speed results in the output relay changing state. All models provide a startup alarm delay feature which allows time for the monitored equipment to come up to speed before the unit will alarm.


  • Low cost solid state electronics
  • Adjustable startup alarm delay (0-60 seconds)
  • Models available with NEMA 4/5 Rating (weatherproof and dust tight) or NEMA 7/9 Rating (Explosion Proof [EP models cannot exceed 100 RPM.])
  • All models are UL Listed
Dazic® Application Data Sheet
Temperature Range -40° to +160° F

(-40° to +71° C)
Input Shaft Speed 1-300 RPM (Zero & Adjustable Speed models)

1-400 RPM (Digital models)
Input Voltage 120 VAC or 240 VAC at 50/60 Hz (Factory Set)
Output Relay – 5 Amp, DPDT (Double Pole, Double Throw)
Power Consumption 3 Watt
Weight 7 lbs. (3.2 kg)
DAZIC® RotoGuard® III


It takes just 5 clicks to fill out our Data Application sheet. Our Sales Engineer can then recommend the best speed switch for your specific needs.