Arrester with graded capacitance varistors
AssigneeGeneral Electric Company
InventorsLionel M. Levinson, Howard F. Ellis, Herbert Fishman
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Abstract
A station arrester employing metal oxide varistors has varistors whose capacitances increase in a direction measured from the ground side of the arrester. An approximately uniform voltage distribution can be produced across the varistors when appropriately graded according to their positions in the varistor stack. In this configuration, the varistor disks located near the top or line end of the stack are not subjected to increased thermal stresses.
Claims13
An arrester for surge protection of power transmission lines comprising:
- an elongated insulating housing having a ground terminal and a line terminal disposed at opposite ends thereof;
- a plurality of metal oxide varistors disposed within said housing and configured in a stack, said varistors being electrically connected in series, the varistor at a first end of said stack being connected to said line terminal and the varistor at the second end of said stack being connected to said ground terminal, said varistors exhibiting increased intrinsic capacitance with increased proximity to said line terminal.
A metal oxide varistor manufactured from a sintered mixture of zinc oxide and metal oxide additives, said varistor exhibiting a dielectric constant .epsilon. and a breakdown voltage F.sub.1, said varistor comprising zinc oxide grains separated by intergranular material, said varistor also comprising insulating material between said zinc oxide grains such that the product .epsilon.F.sub.1 is less than 1.5.times.10.sup.6 volts/cm.
Dependencies are inferred from the claim text.