On cores and coils. There is eddy current in the electromagnetic core of AC contactor, so the electromagnetic core is made into one piece and stacked together. It prevents electromagnetic release at zero crossing instant. A short circuit ring is added to the core of the electromagnetic iron. The coil turns are less, the current is larger, and the diameter of the coil is thicker. The electromagnetic core of DC contactor is an integral core with slender coils and many turns. If the AC and DC contactors are connected incorrectly, the DC contactor is connected to the AC contactor, and the wire bank is burned immediately. The AC contactor is connected to the DC contactor, and the contactor can not be sucked on the iron core and coil. There is eddy current in the electromagnetic core of AC contactor, so the electromagnetic core is made into one piece and stacked together. It prevents electromagnetic release at zero crossing instant. A short circuit ring is added to the core of the electromagnetic iron. The coil turns are less, the current is larger, and the diameter of the coil is thicker. The electromagnetic core of DC contactor is an integral core with slender coils and many turns. If the AC and DC contactors are connected incorrectly, the DC contactor is connected to the AC contactor, and the wire bank is burned immediately. The AC contactor is connected to the DC contactor, and the contactor can not be sucked on the iron core and coil. There is eddy current in the electromagnetic core of AC contactor, so the electromagnetic core is made into one piece and stacked together. It prevents electromagnetic release at zero crossing instant. A short circuit ring is added to the core of the electromagnetic iron. The coil turns are less, the current is larger, and the diameter of the coil is thicker. The electromagnetic core of DC contactor is an integral core with slender coils and many turns. If the AC and DC contactors are misconnected, the diaphragm is connected to the AC contactor, and the line is burnt immediately. AC is connected to the DC contactor, and the contactor can not be absorbed.