Zero speed switches (ZSS) also known as Speed Actuating Sensing Switches[1] are used to detect whether a rotating shaft is turning (even at very slow speeds) [2] in various machines, conveyors, power plants, and in industries involving the production of cement, sugar, textiles, paper, etc.
Zero speed switches mainly use electromechanical, electronic, or magnetic proximity technologies.
Electromechanical speed switches are direct coupled, speed-indicating devices which open or close a set of contacts mechanically, as a function of the rotational speed of the switch shaft.
A small timing delay may be required for avoiding nuisance tripping during running as well as during starting of the machine.
Zero speed switches differ in terms of performance specifications, mounting styles, and features.