CHAPTER 4 - MECHANICALLY OPERATED SWITCH

MECHANICALLY OPERATED SWITCH

This is switch with the momentary type, a force has to be applied to change the switch from ON to OFF (or OFF to ON). When the force is removed, the switch immediately returns to its original position. Or lets say that mechanically operated switch is one that is controlled automatically by factors such as pressure, position, and temperature.

·         Limit switch is a very common industrial control device which are designed to operate only when predetermined limit is reached and they are usually actuated by contact with an object as cam.

·         Microswitch is a snap-acting switch housed in small enclosure. In a snap-acting switch, as in a toggle switch, the actual switching of the circuit takes place at a fixed speed no matter how quickly or slowly the activating mechanism moves

·         Temperature switches (thermostats) are used to sense temperature changes. Although there are many type available, they are actuated by some specific environmental temperature change. It open or closed when designated temperature is reached.

·         Pressure switches are used to control the pressure of liquid and gases. Again, it will open or close (actuate) until designated pressure is reached. Pressure switches are pneumatically (air) operated switches. Generally a bellows or diaphragm presses up against a small microswitch and causes it to open or close.

·         Level switches are used to sense the height of a liquid. The raising or lowering of a float, which is mechanically attach to the level switch, trips the level switch. The level switches itself is used to control motor-driven pump that empty or fill tanks. Level switches are also used to open or close piping solenoid valves to control fluids.

References:

Petruzella, Frank. 1996. Industrial Electronics. Mc-Graw Hill. Singapore