The main differences between DC contactors and AC contactors:

1. AC contactors use grid arc extinguishing devices, while DC contactors use magnetic blowout arc extinguishing devices.

2. The starting current of AC contactors is large, and their maximum operating frequency is approximately 600 times per hour. The operating frequency of DC contactors can reach up to 1200 times per hour at most.

3. The core of an AC contactor generates eddy current and hysteresis losses, while a DC contactor has no core losses. Therefore, the core of an AC contactor is made of silicon steel sheets insulated from each other and is often shaped like an E; the core of a DC contactor is made of a solid piece of soft steel and is mostly shaped like a U.

4. Since the AC contactor passes single-phase AC, to eliminate the vibration and noise generated by the electromagnet, a short-circuit ring is embedded on the end face of the stationary core, while the DC contactor does not require this.

4. An AC contactor can be used as a substitute for a DC contactor in an emergency, but the closing time should not exceed 2 hours (because the AC coil has poorer heat dissipation than the DC coil, which is determined by their different structures). If it is necessary to use it for a long time, it is best to connect a resistor in series with the AC coil. However, a DC contactor cannot be used as a substitute for an AC contactor.

5. The coil of an AC contactor has fewer turns while that of a DC contactor has more turns. The volume of the coil can be used to distinguish them. In cases where the main circuit current is too large (Ie > 250A), the contactor adopts a series double-winding coil.

6. The coil of a DC relay has a large reactance and a small current. If it is connected to an AC power supply, it will not be damaged and will be switched on and off alternately. However, the coil of an AC relay has a small reactance and a large current. If it is connected to a DC power supply, the coil will be damaged. 5 r: @8 B  G. f, s$ a

7. AC contactors have short-circuit rings on their cores, while DC contactors should, in principle, have none. The cores of AC contactors are generally made by stacking silicon steel sheets to reduce the eddy current and hysteresis losses caused by alternating magnetic fields in the core and prevent overheating. The cores in the coils of DC contactors do not generate eddy currents, and there is no heating issue with DC cores, so they can be made of solid cast steel or cast iron. The coils in DC circuits have no inductive reactance, so they have more turns, higher resistance, and greater copper loss. Therefore, the heat generated by the coil itself is the main concern. To ensure good heat dissipation of the coil, it is usually made into a long and thin cylindrical shape. AC contactors have fewer turns and lower resistance in their coils, but the core generates heat. The coils are generally made into thick and short cylindrical shapes and have a certain gap from the core to facilitate heat dissipation and prevent the coil from being damaged by heat. To eliminate the vibration and noise generated by the electromagnet, short-circuit rings are embedded on the end face of the stationary core of AC contactors, while DC contactors do not require short-circuit rings.