Phares ZS12 Zero Speed Switch


The Phares Model ZS12 Zero Speed Switch Sensor is a rugged, all-in-one device which includes replaceable sensor and relay, for use in over speed, under speed, or zero speed monitoring. It protects your conveyor or other industrial machinery when it slows down, or stops unexpectedly. The ZS12 Zero Speed Switch has an adjustable set point via multi-turn trim pot for precise, accurate speed measurement, and is able to react within a fraction of a second if your conveyor or machine stops abruptly.

When machine shaft speed reaches the set point, the ZS12 Zero Speed Switch relay output changes state. It remains in this state until under speed or zero speed condition occurs. The Phares ZS12 Zero Speed Switch has 3 diagnostic LED’s. These LED’s indicate Power, Pulses from Sensor input signal and Relay status. LED’s are labeled Power, Pulse, and Relay. A multi-turn trim pot is used for adjusting the set point.

The ZS12 Zero Speed Switch has isolated relay contacts making it easy to incorporate into new or existing systems, or to replace obsolete zero speed switches.

Install on augers, bucket elevators, conveyors, exhaust fans, grinders, turbines and many other applications where shaft speed monitoring is needed.


  • Self contained zero speed switch with relay and low profile, replaceable sensor
  • Isolated relay contacts switch up to 5 amps
  • Senses magnetic and high iron content targets (gear tooth, key stock, bolt head, etc.)
  • Universal input voltage – 100 to 240 VAC or 9 to 36 VDC
  • LED indicators for instant visual confirmation
  • Precision trim pot for accurate relay set point adjustment
  • Detect speeds as slow as 0.03 RPM
  • Detect speeds as high as 25,000 RPM


  • Faster than pushing ‘Emergency Stop’
  • No additional control box needed
  • Suitable for outdoor use and in wash down areas
  • Over speed, under speed, or zero speed detection
  • Extend the lifespan of your equipment
  • Stop conveyor “domino” effect
  • Detect unexpected load increase
  • Reduce belt breaks
More Information
Manufacturer Phares
Type Digital Magnetic Speed Sensors
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