Why does DC contactor have economic resistance

Update:20-02-2023
Most DC contactors are high-voltage contactors, adding resistance can ensure the safety of power devices. For example, in new energy electric vehicles or high-voltage packs, due to excessive instantaneous current, a series of pre-charging resistors and other series will be connected to the pre-charging circuit of its high-voltage direct contactor (, or) to achieve safety protection.
Are DC contactors divided into high voltage and low voltage?
The DC contactor has only a small arc extinguishing device, which can only break the overload current of the circuit, and cannot be used to break the fault current and high voltage of the circuit, so it can only be used for low voltage.
Contactors have different rated voltages, and they must be selected strictly according to the rated voltage, such as the coil action voltage has ,,,,, and so on.
What types of relays are commonly used
The relay is an executive component that plays a role in control and isolation in the automatic control circuit. It is actually an automatic switch that can use low voltage and small current to control high current and high voltage.
(2) Types of relays
Commonly used relays mainly include electromagnetic relays, dry reed relays, magnetically latched wet reed relays, stepping relays and solid state relays.
Electromagnetic relays are divided into AC electromagnetic relays, DC electromagnetic relays, high current electromagnetic relays, small electromagnetic relays, normally open electromagnetic relays, normally closed electromagnetic relays, polarized relays, bistable relays, reverse current relays, slow suction relays, Slow release relays, fast relays, etc.
Solid state relays are divided into DC solid state relays, AC solid state relays, power solid state relays, high sensitivity solid state relays, multifunctional switching solid state relays, solid state time relays, parameter solid state relays, passive solid state temperature relays, bidirectional transmission solid state relays, etc. .