APPARATUS FOR LIMITING OVERVOLTAGE Russian patent published in 2013 - IPC H01C7/12 

FIELD: electricity.

SUBSTANCE: in order to increase reliability of the technical state of such devices, currents on the surface of the device and current of the varistor column have to be separated. This separation is provided by insulating the lead from the metal flange. In modern compact devices for limiting overvoltage with polymer housings, insulating the lead while ensuring appropriate air-tightness of the device is difficult. To this end, its cylindrical lead contact and the fabrication hole for injecting a compound are made in form of a hollow metal tube, e.g. a cylindrical steel tube. The outer diameter of the lead contact should be at least $$D=\sqrt{4S_S/\pi +d^2},$$ where S_S is the standardised cross-sectional area of the earthing conductor; d is the assumed diameter of the fabrication hole.

EFFECT: high operating reliability of the apparatus for limiting overvoltage by providing conditions and simplifying sealing of the device when making an insulated lead.

3 dwg