US 7,593,198 B2
Relay circuit
Richard Peter Brereton, Bournemouth (United Kingdom); Duncan Hamilton, Ferndown (United Kingdom); and Daniel Robert Rees, Bournemouth (United Kingdom)
Assigned to P G Drives Technology Ltd., Christchurch, Dorset (United Kingdom)
Filed on May 16, 2007, as Appl. No. 11/798,780.
Claims priority of application No. 0609634 (GB), filed on May 16, 2006.
Prior Publication US 2007/0268640 A1, Nov. 22, 2007
Int. Cl. H02H 3/00 (2006.01); H02H 7/00 (2006.01)
U.S. Cl. 361—8  [361/2; 361/7] 11 Claims
OG exemplary drawing
 
1. A switching circuit for connecting a power source to a load, the circuit comprising a first relay and at least one second relay in parallel arrangement with said first relay arranged such that in the normal “ON” state the first relay and the at least one second relay are in the closed position and the current from the power source propagates along the first and at least one second relay to the load, the circuit further comprising a current/voltage fault detecting system for identifying a fault condition in the event of the current to the load exceeding a predetermined threshold, the switching circuit arranged such that in the event of a fault condition occurring that requires the disconnection of the power source from the load, said at least one second relay opens prior to the first relay such that all the current passes through the first relay, and that said first relay subsequently opens to effect the normal “OFF” state causing disconnection of the power source from the load.