Difference Between Lightning and Surge Arrester
|Fig: Typical Surge Arrester|
Difference between lightning arrester and surge arrester:
If you ask a question ''what is the difference between lightning arrester and surge arrester," answer will be vary from man to man depending on his field of work or his experienced field. We can go some answer:
Lightning arrestor is to provide some degree of protection from Lightning induced problems. Surge arrestor is used to try to limit damaging surges, they can be against current surge, but more usually Voltage surges. . . Could be used on 5V supplies, 12V supplies, Mains 120V or other supply lines. . . Even used on Telephone lines. . . . It all depends on what you want to protect and from what ?
Lightning Arrestors are located at highest elevations of the protected premises and are aimed to direct the discharged currents of lightning strikes through intended circuit to the ground (rather than for instance through the steel structures of a building). Surge Arrestors are voltage limiting devices that are installed on power electric circuits to limit the induced voltages (resulting from, say, switching devices, ground faults, etc.) on power apparatus (mainly) to protect the insulations within withstand levels.
The term "lightning arrester" is no longer used in power transmission. "Surge arrester" is the term used. This is the terminology adopted and followed by IEC. All over-voltages, be it due to lightning or switching or sudden load shedding, is taken care of by a "Surge arrester" in a substation. However, a new terminology, "Line arrester", is being used nowadays for arresters used in LV /MV transmission / distribution lines.
Whenever any inductive load is switched OFF, it induces voltage surges called switching surges into the system (following the equation E = L di/dt). These surges could be harmful to voltage sensitive devices connected in the system. As the contactor coil is inductive, switching of contactors could create switching surges that could harm other equipments. Also, external switching surges could harm the contactor coil itself. A surge suppressor connected to an LV contractor protects the contactor from external surges and also protects the system from being affected by the surges generated due to contractor switching.
But yahoo select the best answer by vote is as below:
This is mainly a matter of semantics. Historically, the motivation for using arresters was to deal with lightning, so they were called 'lightning arresters'. But as system voltage increased, it became apparent that there could be switching-induced surges that were more damaging than lightning, so today, the preferred term is probably 'surge arrester'.
There is a technical distinction between a 'surge suppressor' and a 'surge arrester' that has to do with the energy dissipation capability built into the device. The device that most people plug computers into is a 'surge suppressor' and has a fairly low energy dissipation capability. It also has a voltage rating that is only slightly greater than the normal system voltage. A typical 'surge arrester' has a far greater energy dissipation capability, and the voltage rating is driven more by the surge voltage withstand capability of the insulation being protected than by the rated system voltage.