Electric Switches Industry Information

IQS Newsroom Articles on Electric Switches

Electric switches, electronic switches or electrical switches are devices used to connect or break an electrical circuit. All switches consist of an operator, contacts and a switch mechanism. The operator actuates switch operation. The contacts are made of low-resistance metal and are used to make or break the electrical circuit. The switch mechanism is linked to the operator and opens/closes the contacts. The function of the switch is designated by the terms pole, throw and break. Pole indicates how many circuits a switch is capable of controlling. Throw refers to how many conductors or paths that a switch is able to control. Break is a term that refers to the breaking or opening of a circuit. The term "position" indicates how many stops a switch will make between its extreme settings.

The two most basic switch devices, of which other mechanisms are simply variations, are the slow-make, slow-break (AC base) and the quick-make, quick-break (AC/DC base) mechanisms. The first device is basically a teeter-totter or seesaw design. It is spring-loaded, requiring a very positive force to close the contacts. The slowness of a slow-make, slow-break device provides a slight time delay. This delay allows the AC current wave to nearly instantaneously cycle to zero before the spark is extinguished. Toggle switches, slide buttons, rocker switches or pushbutton switches can operate the mechanism.

The operator of a quick-make, quick-break device is similar to a trigger on a gun. It provides an irreversible action when tripped. The almost instant action is suitable in DC applications, as the more rapidly the contacts are separated, the sooner the arc of current is extinguished. The mechanism of a quick-make, quick-break device uses a compression type motor spring to provide the snap action. Quick-break, quick-make mechanisms are smaller and more compact than slow-make, slow-break mechanisms but are more costly. Quick-make, quick-break mechanisms also have self-wiping contacts to prevent corrosive buildup.

Although the circuit configuration possibilities for electronic switches are virtually endless, typical circuits include single-throw, double-throw without center off, double-throw with center off and double-throw momentary action with center off. The single-throw switch is the most basic circuit with only two positions: on and off. Double-throw switches without an off position in the center are referred to as ON-ON switches. These manual electric switches are commonly used in selector applications (e.g. 6V or 12V on a battery charger). Double-throw electric switches with a center off position are three-position switches with two independent ON switches, an example of which is the HI-OFF-LOW settings of a kitchen range hood exhaust fan. Three-position double-throw electric switches with momentary action use a spring loading action. As long as pressure is applied to the actuator, the position will be maintained, making these electronic switches operator-dependent.