Re: cord and plug connected machinery
A drop out contactor is a device that prevents a motor from restrting automatically after a loss of power. These are commonly used on mixers, drill presses, table saws, and other devices where you might have your hand where it shouldn't be during a return of power. there are many ways to accomplish this protection, a contactor is only one of them.
The NEC does not require these. OSHA does require them. Many local building codes also require them especially in school "shop" classrooms.