The AC circuit you mentioned is a dual power automatic transfer switch capable of working with single-phase or three-phase power systems. It has a capacity of 16A to 63A, indicating the maximum current it can handle, and operates at a voltage of 400V. The transfer switch can be configured to work with either two-pole (2P), three-pole (3P), or four-pole (4P) systems. This flexibility allows it to adapt to different types of electrical circuits and installations. The primary function of this transfer switch is to provide automatic switching between two power sources. It is commonly used to transfer the load from the main power supply to a backup power source, such as a generator, in the event of a power outage or disruption. It is designed for both single-phase and three-phase applications, making it suitable for use in both residential and commercial settings. The changeover switch feature allows for a smooth and seamless transition between power sources, ensuring a continuous supply of electricity to essential loads. Overall, this dual power automatic transfer switch is a reliable and efficient solution for managing power transfers between different power sources in both single-phase and three-phase electrical systems.