| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the load of zinc oxide element against the lightening- resistant mechanism and improve the protection mechanism by providing an inside electrode forming a gap in a space toward the central conductor in the internal circumferential face of an annular zinc oxide element body provided as surrounding a central conductor transmitting an electric power to a power supply device by penetrating a bushing mounted to the tank of the power supply device. SOLUTION: When an abnormal voltage such as a lightening impulse, etc., is applied between an central conductor 4 and an earth connected to a tank 1, discharge starts toward an inside electrode 6B of a zinc oxide element 6 through a series gap 11 set at a prescribed clearance from the central conductor 4. Secondly, overcurrent flows radially from the inside electrode 6B toward an outside electrode 6C via the body 6A so as to be discharged from the outside electrode 6C via a lead wire 7 and a tank 1 to the earth. The lightening resistance mechanism of the lightening resistance bushing can be thus distributed between the zinc oxide element 6 and the series gap 11 so that the discharge voltage of the zinc oxide element 6 can be suppressed to low and the lightening resistance mechanism can be improved.</p> |
