Current Uses
Though used commonly in the past, knife switches are now rare, finding use largely in science experiments where the position of the switch may be plainly seen in demonstration. The knife switch is extremely simple in construction and use, but its exposed metal parts present a great risk of electrocution, and the switch is subject to arcing when opened at higher voltages, which poses a further risk of shock or burns to the operator and can cause fires or explosions under certain conditions.
Open knife switches were supplanted by safety switches with current carrying contacts inside a metal enclosure which can only be opened by switching off the power. In modern applications, automatic switches (such as contactors or relays), and manual switches such as circuit breakers are used. These devices use a snap action mechanism which opens the switch contacts rapidly, and feature an arc chute where the arc caused by opening the switch is quenched. These devices also prevent injury due to accidental contact, as all of the current carrying metal parts of the switch are hidden within or surrounded by insulating guards.
Read more about this topic: Knife Switch
Famous quotes containing the word current:
“If the current is right, one can drift to success.”
—Mason Cooley (b. 1927)
““I” is a militant social tendency, working to hold and enlarge its place in the general current of tendencies. So far as it can it waxes, as all life does. To think of it as apart from society is a palpable absurdity of which no one could be guilty who really saw it as a fact of life.”
—Charles Horton Cooley (1864–1929)