Back to results
US 4,288,833 AGranted
Lightning arrestor
AssigneeGeneral Electric Company
InventorEdward K. Howell
Life of this patent
Estimating the term…
Abstract
A metal oxide varistor (MOV) is directly electrically connected between a line conductor and ground to dissipate the energy associated with voltage surges appearing on the line conductor. A thermostatic switch, in the form of a resilient arm held in electrical connection with one of the MOV electrodes by low melting point solder, opens in response to a failing MOV to insert a spark gap electrically in series with the MOV. Overvoltage protection is thus maintained, albeit limited to higher level voltage surges.
Claims13
A lightning arrestor comprising, in combination:
- A. a voltage-dependent resistor having terminals for electrical connection between a line conductor of a power distribution circuit and ground;
- B. normally closed thermostatic switch means electrically connected in series with said resistor, said switch means being thermally coupled with said resistor such that heat generated by said resistor in response to excessive leakage current flowing therethrough under normal line voltage conditions causes said switch means to open and thereby interrupt the flow of said excessive leakage current;
- and
- C. a spark gap electrically connected in series with said resistor by the opening of said switch means, said spark gap preventing the flow of said excessive leakage current through said resistor and having a predetermined breakdown voltage such as to provide effective distribution circuit overvoltage protection, said resistor acting to dissipate the energy associated with line voltage surges in excess of said breakdown voltage and to insure deionization of said spark gap as each line voltage surge subsides.
1 more element
Dependencies are inferred from the claim text.