Surge protector

A surge arrester ( UESP, English:. Surge Protective Device SPD) is a device or component to limit dangerous overvoltages in electrical cables and equipment. For efficient surge protection is the purpose of a customized combination of different surge.

General

Overvoltages can be caused by direct or nearby lightning strikes, by caused by the sun magnetic storms, by an electromagnetic pulse (EMP ) caused by electrostatic discharge ( ESD) or switching operations in the power network and in devices and accordingly have sometimes considerable energies.

When surge arresters are used:

With Suppressors particular signal inputs are protected from electrical devices secured at low voltages. They tolerate only low energies, however, offer a close-tolerance protection level.

Varistors protect the line voltage input of equipment or areas in danger of electricity networks (eg Building Lightning Protection, the inputs and outputs of large transformers and traction power - substations ).

With gas discharge tubes to protect signaling and partially also power lines when very high Ableitenergien be expected.

Protection of overhead lines

Before the development of sufficiently good varistor (low current at rated voltage, long life ) was used for the protection of overhead lines from the effects of a lightning strike:

Overhead line insulators protects you with spark gaps from the direct effect of induced lightning arcs. Keep the arc away from the insulating material and, through their design often the quenching of the arc at ( Hornableiter ). Not extinguish the arc, the network section is off, and, automatically switched on again by means of short break after a short time.

In Pictured on the right picture Surge is a stack of varistor discs which are, for example, conductive when lightning strikes and, for example, a - not visible in the picture - protect transformer or a wiring against overvoltage.

Protection of small appliances

Isolate gas filled surge arresters, as long as the voltage remains and do not interfere because of their low capacity of only about 2 pF below about 450 volts. If the ignition voltage is exceeded, the resistance falls within microseconds to very low levels, with current peaks can be derived up to 20000 A. In continuous operation, they will be thermally overloaded.