Varistors with controllable voltage versus time response
AssigneeGeneral Electric Company
InventorLionel M. Levinson
Life of this patent
Estimating the term…
Abstract
A bismuth-free, zinc oxide based varistor exhibits a controllable overshoot/undershoot voltage characteristic. The varistor is composed of zinc oxide as the primary constituent, with smaller quantities of barium, boron, one or more transition elements and aluminum. Varistor voltage versus time response is dependent on the degree of aluminum doping. Typically, more than approximately 0.003 mole percent, but less than approximately 0.1 mole percent aluminum is employed, depending on desired voltage overshoot/undershoot characteristic.
Claims9
A sintered ceramic, bismuth-free metal oxide varistor composition consisting essentially of between about 70 and 99.5 mole percent ZnO as a primary constituent, and finite quantities of additive oxides of barium, boron, aluminum, and at least one additive transition element oxide, said finite additive quantities in aggregate comprising between about 0.5 and 30 mole percent of said composition.
A varistor made from a sintered mixture consisting essentially of 0.5 mole percent of each of BaCO.sub.3, NiO, Co.sub.2 O.sub.3, and MnO.sub.2, 1 mole percent H.sub.3 BO.sub.3, and between 0.003 and 0.1 mole percent Al(NO.sub.3).sub.3, the balance being ZnO.
Dependencies are inferred from the claim text.