Inventors:
Manfred E. Neumann - New Berlin WI
Assignee:
Siemens-Allis, Inc. - Atlanta GA
International Classification:
G05F 114
Abstract:
A tap changer voltage regulator permits a tap changer switch selector contact to engage an open circuited new tap without arcing and has a half-tap voltage auxiliary winding which permits halving the voltage being interrupted and doubling the number of steps and also has an auxiliary switch with a first movable contact which initially connects the selector contact on the new tap in series with a circulating current limiting inductor and the load to prevent load circuit interruption and is provided with a second movable contact in series with a pair of normally closed contacts through which flow the load current and the current which circulates while the selector contacts bridge adjacent taps during the tap change. The normally closed contacts are shunted by a pair of inverse parallel thyristors. The auxiliary switch then opens its normally closed contacts to transfer the current to the thyristors and subsequently removes gating current from the thyristors so that load and circulating current are statically interrupted by one of the thyristors at current zero, thereby permitting the second movable contact to arclessly interrupt the circuit to the selector contact on the previous tap to complete the tap change.
