The use of the magnetic coil in the controller also affords many options as you mentioned, i.e. various temp and pressure shut downs. The operation of the motor controller is not that complicated, the devices (temp or pressure switches such as barksdale
Barksdale Inc | Series 96200) are wired into current path for the coil such that they open at desired temp or pressure to interrupt the current to the coil, the coil unlatches, and the motor stops. The only way for the motor to restart, is for those conditions that caused the corresponding safety action to clear (temp or pressure to drop below level at which the switch changes state) so that the current path for the coil is restored. And for the magnetic starting sequency (ie push the start button) to be initiated. The start button is put in parallel with the ouput of the main contacts. The start button is also of a momentary type, when you push the start button, current runs through the coil to close the main contacts. When you release the start button, the power to maintain the coil energized comes from the load side of the main contacts. You can shut down the motor by pressing the stop button, which interupts current through the coil, or if any of the safety devices (temp or pressure switches) changes states and interrupts current through the coil.
This type of motor controller can be used with single or three phased motors of any size.