Experimental and analytical studies of the effects of multiple lightning impulse currents on metal-oxide arrester blocks

The multiple lightning strokes are the main cause of distribution arresters failures. In order to evaluate performance of distribution lines arresters more realistically, the experimental and analytical studies of the effects of multiple lightning impulse currents on metal-oxide arrester blocks are carried out. The multiple impulse current generator developed by Shanghai Jiao Tong University is adopted, the generator could output four impulse current representing one first stroke current, two subsequent stroke current and one continuing current of interval stroke, respectively. The variable interval time between the two impulses could achieve as low as 1 ms. The effects of block dimension, interval time between impulse currents, the sequences of impulse currents and the amplitude of impulse currents are studied. The results show larger amplitude of multiple impulse current, less interval time between impulse currents and smaller geometric parameter of arrester block are the causes of blocks failure. Surface flashover and energy absorption are two failure characteristics under multiple impulse current. The DC 1mA reference voltage is more sensitive than the residual voltage of blocks under multiple impulse current. The multiple impulse currents tests are suitable for performance evaluation of distribution lines arresters under natural lightning stroke.