Patent ID: 8085002

Claim:
An apparatus, comprising: a power switch device to selectively provide AC electric power on the power distribution bus from one of a local power source and an external power interface, including: a first normally open contactor between the external power interface and the power distribution bus, a first switch, and a first contactor state control; a second normally open contactor between an inverter and the power distribution bus, a second switch, and a second contactor state control; an external power control circuit through the first switch and the first contactor state control, the external power control circuit having a default closed state when external power is available at the external power interface, the default closed state of the external power circuit providing electricity from the external power interface to the first contactor state control to close the first normally open contactor and correspondingly route the AC electric power to a power distribution bus from the external power interface; and a local power control circuit through the second switch and the second contactor state control, the local power control circuit having a default open state when the external power circuit is in the default closed state.