Surge protective device (SPD) is suitable for 3-phase power distribution system like IT, TT, TN-S etc. The SPD has two protection modes, L-PE/N-PE and L-N/N-PE. The SPD features a large current capacity, low residual voltage and also has built-in alarm function for the thermal runaway.
SPD DimensionsTips: Protection grade of surge protection device Because of the huge energy of a lightning strike, it is necessary to gradually discharge the energy of lightning strike to the earth through a step-by-step discharge method. The Class I arrester can discharge the direct lightning current, or discharge the conducted huge energy when the power transmission line is suffering a direct lightning strike. For places where direct lightning strikes may occur, Class I arrester for lightning protection must be applied. The Class II surge protection device is used as a protective device for the residual voltage of the primary arrester and for inductive lightning stroke in the area. When the primary arrester absorbs large lightning strike energy, there is still a part of energy transmitting to the devices or Class III surge protectors and the energy is quite large to them. Therefore, it needs a Class II surge protection device to further absorb it. At the same time, the transmission line passing through the first stage of the lightning arrester will also induce the electromagnetic pulse of lightning strikes. When the line is long enough to sense the energy of the lightning which will become large enough, it is required that Class II surge protection device do the further discharge of the lightning strike energy. The Class III surge protection device protects the equipment or device from residual lightning strike energy which pass through the electromagnetic pulse and Class II lightning protection device.
Surge Protection Device Catalogue.pdf