To the right is an illustrated schematic animation that contains a three phase motor starter with a hand off auto switch with start stop buttons.
MS1 is the motor starter.
The Hand Off Auto Switch is a three position switch with two sets of contacts. one set is made in hand and the other is made in auto.
The Red Lines show the circuit path.
The Switch is the heart of the circuit's path.
When the switch is in the off position there is no path to the coil and the starter can't run.
When in the hand position the path is directly connected to the coil and the starter is running the motor.
When in auto the start stop buttons control the starter.
When the start button is pushed the path is complete to the coil going thru the auto side of the switch.
When the coil is energized the contacts from MS1 close holding the power to the coil until the stop button is pushed or the switch is turned off interrupting the circuit's path.
Watch the circuit work to see what happens