Patent ID: 8643221

Claim:
A retrofit kit for reconfiguring a tap changer having contacts subject to electrical arcing, the kit when installed in the tap changer configured so that said contacts are not exposed to said electrical arcing, the kit comprising: a vacuum switch assembly comprising a first vacuum interrupter to be electrically coupled to a first electrical contact of the tap changer, the vacuum switch assembly further comprising a second vacuum interrupter to be electrically coupled to a second electrical contact of the tap changer, the first and second contacts selectively movable with respect to a plurality of taps of a regulating transformer of the tap changer, the first and second contacts to be electrically coupled to at least one of the plurality of taps of the regulating transformer, wherein the first vacuum interrupter has a first terminal to be connected in series circuit with said first electrical contact and wherein the second vacuum interrupter has a first terminal to be connected in series circuit with said second electrical contact, wherein each of the first and the second vacuum interrupters is respectively connected to the first and second electrical contacts of the tap changer by way of a respective direct electrical connection free of an electrical impedance element; and a controller configured to generate respective actuating signals so that the first and second vacuum interrupters are selectively actuated to a respective circuit-interrupting condition when a tap change is performed to avoid electrical arcing on said first and second movable contacts.