Starters also known as Contactors are required as a hardware disconnect on all motorized machinery.
They range from ordinary single contact to specialized ones like reversers and Definate-purpose style (Air conditioners and welders/ plasma etc).
The DIN style are now popular due to their smaller size than the NEMA counter part.
They are pricey, A good source is Ebay.
The overload trip is the optional module that fits on the output side of the contactor.
Sized according to the motor.
Another similar device is a safety relay as a E-stop device, I believe it is mandatory in most of Europe and N.America is presently coming on board.