Difference between DC contactor and AC contactor
The function of the contactor is functionally used to isolate and cut off or pull in the electrical circuit. In essence, the AC contactor and the DC contactor are the same in terms of contacts, but the coil design is different, and the voltage used is Just the same.
The AC contactor consists of an electromagnetic system, a contact system, an arc extinguishing device, and a housing base. AC contactor has the following characteristics:
- The core and armature are made of silicon steel sheets;
- AC voltage pull-in coil has large impedance;
- Short-circuit rings are embedded in both the dynamic and static armature;
- It has main contacts that are turned on or off and auxiliary contacts of varying numbers. The main contacts are provided with arc-extinguishing devices;
DC contactors have the following characteristics:
- Both the core and the armature are made of a single piece of solid material instead of silicon steel sheets;
- The DC voltage coil has a large DC resistance value;
- It has DC main contacts and auxiliary contacts of varying numbers. Some of the main contacts have arc extinguishing devices and some do not have arc extinguishing devices;
DC contactor in new energy vehicles and charging piles
For DC charging pile, DC output side of charging station or for output side of car charger. When the contactor is closed, it plays the role of communication between the charging pile and the car; when it is disconnected, it isolates the connection between the charging pile and the outside and plays a role of safety protection.
A DC contactor is arranged between the battery system of the electric vehicle and the inverter. When the system stops running, it acts as an isolation, and when the system is running, it acts as a connection. When the vehicle is shut down or malfunctions, the energy storage system can be safely separated from the vehicle’s electrical system to play a circuit breaking role. Used as power control device in other auxiliary circuits.
Important technical indicators:
- After the system stops running, it plays the role of isolating the power end and the load end; (important technical indicators: rated insulation voltage);
- When the system is running, it plays the role of connecting the power end and the load end; (important technical indicators: agreed heating current);
- In the event of a fault, it acts as a breaking circuit. (Important technical indicators: maximum operating voltage)
Characteristics of DC contactors in new energy vehicles and charging piles
Different from general industrial contactor products, the use of environmental conditions has more stringent requirements for the adaptability of contactors for electric vehicles . It must also meet the basic conditions of wide temperature range, high protection level, and high vibration resistance.
Safety and reliability are the first and most critical factors for measuring DC contactors of electric vehicles, which are mainly reflected in arc extinguishing capability and insulation voltage.
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