Generator Transfer Switches
What is a transfer switch?
Generator Transfer Switches are the key to the safe and convenient operation of generators for standby power. A transfer switch is an electrical switch that switches a load between two sources. Using generator power, transfer switches eliminate the risk of back feeding the electrical utility, which can cause injury and property damage. An Automatic Transfer Switch (ATS) is often installed where a backup generator is located, so that the generator may provide temporary electrical power if the utility source fails.
For example, in a home equipped with a backup generator and an ATS, when an electric utility outage occurs, the ATS will tell the backup generator to start. Once the ATS sees that the generator is ready to provide electric power, the ATS breaks the home's connection to the electric utility and connects the generator to the home's main electrical panel. The generator supplies power to the home's electric load but is not connected to the electric utility lines. It is necessary to isolate the generator from the distribution system to protect the generator from overload in powering loads in the house and for safety, as utility workers expect the lines to be dead. When utility power returns for a minimum time, the transfer switch will transfer the house back to utility power and command the generator to turn off, after another specified amount of "cool down" time with no load on the generator.
Homes with standby generators may use a transfer switch for a few circuits or the whole home. A transfer switch can be set up to provide power only to critical circuits (Sub Panel) or to entire electrical panels.