The electromagnetic system of DC contactor consists of coil, iron core and armature. It adopts the clapper-type that the armature turned around the corner angle. Because the coil is connected to the direct current, there will be no eddy current and heat caused by hysteresis loss. Iron core can be made of cast steel or cast iron. The iron core end face also does not need to be installed with the short circuit ring. In order to ensure that the armature can be reliably released after the coil power off, the non-magnetic gasket is often used in the magnetic circuit, which to reduce the effect of residual magnetism.
The number of turns of dc contactor coil is more than ac contactor coil. The large resistance value and the large copper loss, is the main part of the contactor heating, in order to make the coil cooling well, generally make the coil to be long and thin tubular, and do not set the skeleton, so the coil and iron core spacing is very small, which can help the heat dissipation of iron core.