Frank Assaro: Hi! I am Frank Assaro with Cummins Onan. Today I will be discussing how a back up generator system operates.

A residential stand by power system typically has four basic elements; a generator, a battery, a transfer switch and a service entrance breaker. The generator produces electricity for essential or selective systems like cooling, heating, security, refrigeration and lighting.

Your back up needs simple or more extensive, determine the size and output of the unit. A battery is placed within the enclosure and is relied on to start the generator when the power goes out. The battery is maintained via a trickle charger.

The transfer switch immediately senses when utility power is interrupted and transfers power generation responsibility to the generator. Once it senses that power is restored, it transfers the load back to the utility source and signals the generator to cool off and shut down.

At this point most back up power systems will run for about another five minutes to properly cool down. And that's basically how a back up power system operates.