Automatic transfer switches continually monitor utility power. Any anomalies such as voltage sags, brownouts, spikes, or surges will cause the internal circuitry to command a generator to start and will then transfer to the generator when additional switch circuitry determines the generator has the proper voltage and frequency. When utility power returns or no anomalies have occurred for a set time, the transfer switch will then transfer 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.