What is "lightning arrester"

Lightning \Light"ning\ (l[imac]t"n[i^]ng), n. [For lightening, fr. lighten to flash.]

1. A discharge of atmospheric electricity, accompanied by a vivid flash of light, commonly from one cloud to another, sometimes from a cloud to the earth. The sound produced by the electricity in passing rapidly through the atmosphere constitutes thunder.

2. The act of making bright, or the state of being made bright; enlightenment; brightening, as of the mental powers. [R.]

   Ball lightning, a rare form of lightning sometimes seen as a globe of fire moving from the clouds to the earth.

   Chain lightning, lightning in angular, zigzag, or forked flashes.

   Heat lightning, more or less vivid and extensive flashes of electric light, without thunder, seen near the horizon, esp. at the close of a hot day.

   Lightning arrester (Telegraphy), a device, at the place where a wire enters a building, for preventing injury by lightning to an operator or instrument. It consists of a short circuit to the ground interrupted by a thin nonconductor over which lightning jumps. Called also lightning discharger.

   Lightning bug (Zo["o]l.), a luminous beetle. See Firefly.

   Lightning conductor, a lightning rod.

   Lightning glance, a quick, penetrating glance of a brilliant eye.

   Lightning rod, a metallic rod set up on a building, or on the mast of a vessel, and connected with the earth or water below, for the purpose of protecting the building or vessel from lightning.

   Sheet lightning, a diffused glow of electric light flashing out from the clouds, and illumining their outlines. The appearance is sometimes due to the reflection of light from distant flashes of lightning by the nearer clouds.

n. A device used on electrical and telecommunications systems to protect the insulation and conductors from the damaging effects of lightning. Typically, it has a high-voltage terminal and a ground terminal. When a surge travels along the power line to the arrester, the current from the surge is diverted through the arrester, in most cases to earth.

n. electrical device inserted in a power line to protect equipment from sudden fluctuations in current [syn: surge suppressor, surge protector, spike suppressor, spike arrester]

A lightning arrester is a device used on electrical power systems and telecommunications systems to protect the insulation and conductors of the system from the damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge (or switching surge, which is very similar) travels along the power line to the arrester, the current from the surge is diverted through the arrestor, in most cases to earth.

In telegraphy and telephony, a lightning arrestor is placed where wires enter a structure, preventing damage to electronic instruments within and ensuring the safety of individuals near them. Smaller versions of lightning arresters, also called surge protectors, are devices that are connected between each electrical conductor in power and communications systems and the Earth. These prevent the flow of the normal power or signal currents to ground, but provide a path over which high-voltage lightning current flows, bypassing the connected equipment. Their purpose is to limit the rise in voltage when a communications or power line is struck by lightning or is near to a lightning strike.

If protection fails or is absent, lightning that strikes the electrical system introduces thousands of kilovolts that may damage the transmission lines, and can also cause severe damage to transformers and other electrical or electronic devices. Lightning-produced extreme voltage spikes in incoming power lines can damage electrical home appliances or even produce death.