Paddle Switch Working Principle

Paddle Type Level Switch is used for level detection for powder or bunk material in silo,hoppar,etc.

The rotating paddle is continuously rotates by a motor. When this paddle contacts with the material, the force more than the rotating torque will be applied to the paddle and the rotation will stop.

The Level Switch detects rotation ⇔ stop and outputs the contact.


The principle is based on the moment of resistance change of a rotating paddle in air or a medium.

The electrically driven, slowly rotating paddle (frequency = 1Hz) is on the level of the selected limit.

The rising product brakes the rotation, the hinge-mounted drive system changes its position and triggers a microswitch.

As the level moves down, the drive returns to its original position by spring force and the microswitch restarts the motor.

Paddle switch Working Principle


  • Point level detection in bulk solids
  • The universally usable paddle point level switch is employed as a full, empty and requirement alarm in silos with bulk solids.


  • Automatic rotation monitoring (optional)
  • Recognition of failures without dismantling the instrument
  • Easy installation
  • Robust plastic housing with transparent cover
  • Cover securing device
  • Density setting without any tools

Article Source: Endress+Hauser

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