Magnetic motor starters help protect expensive motors from costly overload damage. Heavy-duty motor starters include a contactor that completes the circuit to the motor and an electromagnetic overload relay that monitors the current the motor is drawing. They are most commonly used to safeguard larger 3-phase motors in industrial applications. A magnetic starter's electromagnetic relay is significantly more sensitive than a conventional thermal overload relay, so it can protect motors more effectively. These electric motor starters are available in a wide range of amp and voltage levels.