VARISTOR COATED WITH SHIELDING AND INSULATING LAYER Russian patent published in 2006 - IPC H01C7/10 

FIELD: electrical engineering.

SUBSTANCE: proposed varistor that can be used as surge protective device for high-voltage power transmission lines, miscellaneous stationary and mobile (vehicle-mounted) power installations is, essentially, zinc oxide based sintered element whose butt-end surfaces mount electrodes. Varistor side surface is coated with vitreous layer made of fusible glass, proportion of its components being as follows, mass percent: PbO, 48.5 - 51.5; ZnO, 21.5 - 22.5; B₂O₃, 11.5 - 13.5; SiO₂, 11.0 - 12.5; Al₂O₃, 1.5 - 2.5; ZrO₂, 1.5 - 2.5. Proposed proportion of components makes it possible to produce shielding and insulating layer on varistor side surface at lower temperatures and to vitrify varistors simultaneously with their pre-burning.

EFFECT: improved coordination between temperature coefficients of linear expansion of vitreous layer and varistor ceramics, reduced glass softening temperature.

2 cl, 1 dwg, 2 tbl