Abstract: A method and apparatus for controlling a device by detecting a silicon controlled rectifier (SCR) thereof, as well as a method and apparatus of automatic transfer switch controller thereof are disclosed. In one embodiment, the apparatus includes an input configured to receive input power, an output configured to provide said input power to a load a switch unit electrically coupled between said input and said output, the switch unit having at least one silicon controlled rectifier (SCR), a control unit electrically coupled to the switch unit for detecting the SCR of said switch unit and configured to provide a driving signal, and a device, which is driven by said control unit, wherein the driving signal is determined by the control unit after detecting a voltage value between the gate electrode and the cathode electrode of said SCR.