What is the importance of knife switch?

Answer 1

A knife switch is a type of switch used to control the flow of electricity in a circuit. It is composed of a hinge which allows a metal lever, or knife, to be lifted from or inserted into a slot or jaw. The hinge and jaw are both fixed to an insulated base, and the knife has an insulated handle to grip at one end.

Answer 2

it is a form of switch- all or nothing-0n and off, and for this reason it is often used as a master switch or main-disconnect. the single pole single throw has one switch blade, not the cutlery variety, which vaguely resembles a knife, hence the name, went he handle is down and in the contacts the switch is closed and the power is on. lifting the handle disconnects the circuit. they are somewhat obsolescent, but are retained for instructional purposes in shop and science classes, so there is a limited market for the smaller sizes. On the other hand a DPDT- Double Pole Double throw switch- or circuit breaker, is in everyday use and has defied obsolescence since the days of Edison. the DPDT is used on master switches and controls two circuits, usually with a center off position. Thet were used as aerial switches- to select transmit or receive in early shortwave and ham sets. they are very much around and have been nicknamed (Mousetraps) from their shape and outline. very much in use and I have a l907 electrical handbook that illustrates them some have shunts or condensers across the base ( wood or plastic, usually) of the switch. this has various uses but keeps the currents at a safe value in radio use.