Apparatus and method for powering load center circuits with an auxiliary power source

A power distribution apparatus for use with a primary power supply and an auxiliary power supply, comprising:

• a cabinet;
• a bus arrangement having a first set of circuit breakers, the bus arrangement contained within the cabinet;
• a transfer electrical bus arrangement having a second set of circuit breakers, the transfer electric bus arrangement contained within the cabinet;
• a manual transfer switch assembly associated with the bus arrangement and an automatic transfer switch assembly associated with the transfer electrical bus arrangement, wherein the manual transfer switch assembly includes a primary power input switch that is fed primary power, a primary power feedback switch interconnected between the primary power switch and the bus arrangement, and an auxiliary power input switch that may be fed auxiliary power interconnected between the auxiliary power supply and the bus arrangement;
• and
• an interlock assembly associated with the manual transfer switch assembly that electrically isolates the automatic transfer switch assembly from the manual transfer switch assembly when auxiliary power is energizing the first set of circuit breakers.

An electrical panel assembly for use with a primary power supply and a secondary power supply that is used to supply power during interruption of the primary power supply, the panel comprising:

• a first set of circuit breakers connected to a first bus and a second set of circuit breakers connected to a second bus, wherein one of the first set of circuit breakers includes a feeder breaker adapted to electrically connect the second set of circuit breakers to the first bus;
• a power input switch adapted to electrically connect the first bus to the primary power supply when in a first position and electrically isolate the first bus from the primary power supply when in a second position;
• a primary power feedback switch adapted to signal the presence of an operative primary power supply when in a first position and to signal whether the primary power supply is operative when in a second position, the primary power feedback switch having an output connected to control circuitry operative to automatically activate the secondary power supply upon interruption of primary power;
• a manual transfer switch associated with the power input switch and the primary power feedback switch and an automatic transfer switch;
• wherein the manual transfer switch connects the first set and the second set of circuit breakers to the primary power supply when in a first position and may connect only the first set of circuit breakers to the secondary power supply when in a second position, and
• wherein the automatic transfer switch connects the second set of circuit breakers to the primary power supply, through the manual transfer switch, the first bus, and the feeder breaker, when in a third position and automatically connects the second set of circuit breakers to the secondary power supply during interruption of the primary power supply and automatically disconnects the second set of circuit breakers from the first bus during interruption of the primary power supply, wherein the signal for the interruption of the primary power supply is sent by the primary power feedback switch.

In an electrical power distribution system that includes a primary power supply, a secondary power supply, one or more first electrical circuits, one or more second electrical circuits, and an automatic transfer switch that supplies electrical power from the secondary power supply to the second electrical circuits upon interruption in the supply of power from the primary power supply, a method of supplying power from the secondary power supply to the one or more first electrical circuits when the supply of power from the primary power supply is interrupted, comprising the acts of:

• sensing interruption of primary power;
• connecting the second electrical circuits to the secondary power supply through the automatic transfer switch when power from the primary power supply is sensed as interrupted;
• selectively connecting the first electrical circuits to the secondary power supply during interruption of the primary power supply;
• and
• wherein selectively connecting the first electrical circuits to the secondary power supply automatically prevents connection of the primary power supply to the first electrical circuits and prevents the sensing of a return of primary power.