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Analysis of new energy automobile HVDC relay and contactor (1)

Jan 15, 2019

If the relay and dc contactor is a power switch, what is difference with ordinary switch?

High voltage relays are mainly used in remote control switches with high voltage and large current.

In high voltage and large current, any circuit on and off operation will produce arc or spark, the higher the voltage, the longer the arc, the greater the current and the greater the heat generated, An elongated arc may strike the operator or controller circuit or burn out the control board at high temperatures, rendering it useless.

For our daily household voltage of 220V current is only about 10A, Just use a regular switch.

However, the special switch used in the high-power and high-current industry is too complex and bulky, and the control energy consumption is huge, so it is only suitable for specific projects

Thus developed to meet the requirements of miniaturization, large current, low consumption, safe arc extinguishing remote control switch relay and widely used in the new energy industry

Why do relays have positive and negative poles?

Not all relay contacts are divided into positive and negative, only for magnetic blow-out relay, the magnetic field attraction has a certain direction, according to the process from the positive pole into the current is the magnetic field and arc magnetic field suction action, make the arc elongate away from the contact become thin and weak, thus extinguishing the arc.

On the contrary, when the negative pole introduces a current, the current magnetic field and the magnetic field of the magnetic core repel each other, pushing the arc close to the contact, forming a stable arc that is difficult to disconnect.

For the small current relay, the arc power is small and easy to be cut off, so the magnetic core is not used and there is no positive or negative pole, and the volume can also be made smaller, the arc extinguishing mechanism of other processes can also be non-polar, but relatively large volume or excessive consumption of energy, the relay is for the purpose of lightweight, low consumption.

What is the difference between dc relay and ac relay?

For the low-voltage relay, the direct use of control current to distinguish, to dc control on and off said dc relay, ac control said ac relay, the contact can be through dc or ac.

For high voltage relays, in addition use the control current to distinguish, but also use contacts to distinguish. When the contact is dc, the dc is divided into positive and negative poles, and the stable arc direction is the same, and the magnetic blowing process is adopted to extinguish the arc quickly. The contact uses the magnetic blow out arc craft is the direct current relay. When the contacts communicate, the communication is non-polar, the generated arc and direction is weak and self-extinguishing instability, Ac relay can be adopted with arc leakage proof technology.