63a 4pole automatic changeover is an automatic changeover switch, in which the home's power is automatically switched over during an outage of main power. one don't need to manually change to back up power.
changeover switch moves a circuit from a particular set of connections to the other where the switch has both the sets of connections.
automatic changeover has also a manual selection if the homeowner decides to manually change incase he wants to change something
the upper portion of the changeover switch is directly connected to the main power supply while the lower first and right connections slots are connected to the backup power supply like generator or inverter. the left side of lower slots are connected to the main board as load.