Industrial Controls

Zero Speed Sensors


ZSS is used to detect jamming/slow speeding of motor- shafts/mixing screws & there-by stopping the motors/the screws automatically.

It consists of an inductive sensor connected to the control equipment. The sensor senses the rotation of the shaft & in- turn sends pulses to the control unit, which has time dependent logic controller. As long as the motor shaft rotates, the time controller unit senses the rotation & keeps the output potential free relay contacts closed. When the rotations of the shaft ceased, the sensing signal actuates the output relay as to break the output circuits after settable time delay. This switch can be used to protect the motor when the screw is overloaded.

Salient Features:

  1. Input voltage= 240 VAC+/- 10%, 50Hz.
  2. Size of probe= M18 & M30.
  3. Maximum allowable distance 12 to 15 mm (M30).
  4. Separate 3-core cable from supply mains to control unit.
  5. Output of 2NO+2NC changeover potential free relay contacts.
  6. Visual zero speed LED indication.
  7. Maximum Power consumption 5 watts (VA).

When motor is rotating, ‘motor in run position’ LED will light and relay contacts will be energized. When motor stops, ‘motor in run position’ red LED will go off & relay contacts will be de-energized. When the unit is on, the ‘power on’ green LED will light.

A fuse protects the unit. The sensor should be mounted on ‘L’ bracket within 10 mm distance of the rotating shaft.

Operating Voltage (Uc) VAC

Part ID

240 +/- 10%


110 +/- 10%


24 +/- 10%