A contactor is an electrically controlled switch used for switching an electrical power circuit, similar to a relay except with higher current ratings.  A contactor is controlled by a circuit which has a much lower power level than the switched circuit. IEC contactors are most often used by machine builders for a cost-effective solution for motor-starting applications. DIN-rail mounted for amperages from 9A to 150A and panel mounted for models up to 800A, these 3- and 4-pole contactors are available in either AC or DC coil voltages.