Patent ID: 7336003

Claim:
A transfer switch comprising: first terminals adapted to input power from a first power source; second terminals adapted to input power from a second power source; third terminals adapted to output power to a first load; a transfer mechanism adapted to selectively electrically connect either said first terminals or said second terminals to said third terminals; and a control mechanism cooperating with said first terminals, said second terminals and said transfer mechanism to cause said transfer mechanism to electrically connect one of: said first terminals to said third terminals or said second terminals to said third terminals, said control mechanism comprising a control circuit and a relay including at least one normally closed contact and at least one normally open contact, said relay being de-energized by said control circuit responsive to said first terminals being electrically connected to said third terminals, said relay being energized by said control circuit responsive to said second terminals being electrically connected to said third terminals, said at least one normally closed contact being adapted to shed a corresponding at least one second load when said relay is energized, and said at least one normally open contact being adapted to enable a corresponding at least one third load when said relay is energized, wherein said relay is a first relay; wherein said first terminals have a first voltage; wherein said second terminals have a second voltage; and wherein said control circuit further comprises a second relay adapted to be energized by the first voltage of said first terminals, and a third relay including a normally open contact and a first solenoid, said second relay including a first normally closed contact electrically connected in series with said third relay, said third relay being adapted to be energized by the second voltage of said second terminals when said second relay is de-energized and said first normally closed contact thereof is closed, said first solenoid being energized when a second normally closed contact of said second relay is closed and the normally open contact of said third relay is closed, said first solenoid including an auxiliary switch contact adapted to energize said first relay from the second voltage of said second terminals after said second terminals are electrically connected to said third terminals.