How Is The Concept Of DC Contactor And DC Relay Defined, And What Are The Differences in Other Aspects?

1. The contactor is the main circuit component, which is used for switching on and off of the main circuit electric energy; the relay is the component of the auxiliary circuit, which is used for control, signal transmission and amplification, etc.; 2. The contactor needs to withstand the closing and opening of the Inrush current, so the overload multiple of the contactor can reach 8 to 10 times; the current controlled by the relay generally does not have an impact, so the overload multiple of the relay contact is generally 2 times; 3. The contactor has an arc extinguishing device, but the relay does not; 4 The electromagnetic systems of contactors and relays belong to constant magnetic potential, but contactors generally only have voltage coils, while some relays have multiple coils, such as voltage coils and current coils. The current coil is used for pull-in and the voltage coil is used for holding; 5. The contactor coil will be equipped with resistance-capacitance absorption, and relays generally do not; 6. The contactor is a main circuit element, so its contact system has thermal stability parameters and There is no dynamic stability parameter for the relay; 7. The conductive rod of the contactor is plated with tin and nickel to increase the temperature rise, and the conductive rod of the relay is plated with nickel and tin to improve the conductivity. This is mainly the case. ==================== I read the comment area and said that in the condition of low-power motors, relays are used instead of contactors. This is not possible. The reasons are as follows: First: the rated current of a 1.5kW motor is about 3A, its starting current is 3X6=18A, and the starting impulse current is 12X3=36A. The relay can't bear it. Second: When a short circuit occurs, the quick breaking time of the circuit breaker or fuse is 15 milliseconds. During this time, the contactor must be able to withstand the impact of short-circuit current, which is called SCPD. There are two types of SCPD: Type 1 means that the contactor must be replaced after a short circuit, and Type 2 does not require replacement. In general use, it is generally necessary to choose Type 2 to cooperate with the SCPD relationship. The relay has no such capability. Third: The working categories of contactors are AC-3 and AC-4. AC-3 is a direct start, and its overload multiple is 8 times; AC-4 is a forward, reverse, jog and reverse braking, and its overload multiple is 10 times. The working category of the relay is AC-1, which is a non-inductive environment. Fourth: The contactor has an arc extinguishing cover, and the relays do not have an arc extinguishing cover. Therefore, the relay has no arc extinguishing capability at all, while the contactor does. It can be seen that the relay cannot replace the contactor in any way, but the reverse is possible.