Surge Arrester

A surge arrester, also called a surge protector or transient voltage surge suppressor, is a device that protects electrical equipment on an alternating current circuit from short duration voltage spikes, including those caused by nearby lightning strikes, by limiting the voltage that reaches the protected equipment. It works either by blocking a sudden current change with an inductor or by shorting the surge to ground once it exceeds a set threshold, using components such as capacitors, spark gaps, Zener semiconductors or metal oxide varistors, which typically respond within nanoseconds; the energy carried by the surge is then dissipated as heat in the power lines, the ground, or the arrester itself. Surge arresters range from small units built into household power strips or installed at a home electrical panel to heavy duty devices protecting power transmission and distribution systems, telecommunications equipment and industrial machinery, and their key specifications are the clamping voltage at which they activate and the joule rating that measures how much surge energy they can absorb.