Abstract: A method for preventing occurrence of creeping electrical discharge at a resin surface, the method being characterized by including dispersing nanosized inorganic fine particles in a resin, thereby preventing occurrence of creeping electrical discharge at the surface of a cured product of the resin.

Abstract: A method for preventing occurrence of creeping electrical discharge at a resin surface, the method being characterized by including dispersing nanosized inorganic fine particles in a resin, thereby preventing occurrence of creeping electrical discharge at the surface of a cured product of the resin.

Abstract: A signal generator generates a combined signal that is generated only in the period where supply of a pulse signal is effected, a pulse signal whose frequency is of a higher impulse repetition frequency than the frequency of the period setting signal and whose amplitude represents a voltage value that is lower than the high voltage HVDC value. A semiconductor switch accumulates electric charge on a capacitative element by means of the high voltage HVDC from the high voltage generator when the voltage value of the combined signal is lower than the set gate voltage value and generates an impulse voltage whose peak value is the value of the high voltage HVDC, by means of the electric charge that is discharged from the capacitative element when the voltage value of the combined signal exceeds the set gate voltage value.

Abstract: An object is to provide a technique for manufacturing an outer covering rubber having high-voltage electrical insulation characteristics and mechanical characteristics, which are required for a polymer insulator, by decreasing an amount of an additive conducive to improvement in high-voltage electrical insulation characteristics to less than conventional 3% by mass, without using special additional equipment such as ultrasonic agitation. Provided is an outer covering rubber for a polymer insulator, which is obtained by adding an additive conducive to improvement in high-voltage electrical insulation characteristics to a rubber composition, and the additive is a fine powder obtained by crushing a ceramic hydrate into a particle size of 100 nm or less, and the amount of the additive is 0.5 to 2.5% by mass in the entire raw materials of the outer covering rubber for a polymer insulator.

Abstract: A signal generator generates a combined signal that is generated only in the period where supply of a pulse signal is effected, a pulse signal whose frequency is of a higher impulse repetition frequency than the frequency of the period setting signal and whose amplitude represents a voltage value that is lower than the high voltage HVDC value. A semiconductor switch accumulates electric charge on a capacitative element by means of the high voltage HVDC from the high voltage generator when the voltage value of the combined signal is lower than the set gate voltage value and generates an impulse voltage whose peak value is the value of the high voltage HVDC, by means of the electric charge that is discharged from the capacitative element when the voltage value of the combined signal exceeds the set gate voltage value.