To switch on or switch off electric motors, to select operating modes or to perform any operation manually, they must have operator-controlled devices. The buttonholes are hand operated devices which have a single resting position, ie after they have been activated they return to their normal position by the spring twist. They are attached to the panel doors so the operator has quick access and has universal fitting, usually three, for NA or NC contact blocks.
Some models have a https://www.mrosupply.com/sprockets/finished-bore/262280_41bs36-58_martin-sprocket/ translucent surface for the socket of lamp sockets, integrating the signal function, other types have a latch so that they remain activated, it is necessary to turn the knob to release and return to the normal position, it is the case of buttons Mushroom-type emergency. The selectors are rotary drive switches which have two or more rest positions. They are used to select operations or make commands on and off machines or processes; They are more commonly called a knob. The flags indicate specific situations, such as power up, defects, or transient operations.