Genmac ATS Mains Failure Auto Start System 40amp Single phaseGenmac ATS Mains Failure Auto Start System 40amp Single phase Suits Genmac single phase models up to 9kva This automatic transfer switch allows on off control of Genmac generators that are ATS compatible. An ATS (automatic transfer switch) is used to start and stop the generator in the case of power failure. When there is a failure of the primary power source the ATS automatically starts the generator and switches the input power to the generator.