Working principle of power relay
1. The action principle when the contact is closed. When the moving contact and the static contact of the relay touch each other, the contact will jump back, that is, the uncontrolled gap is opened and closed, and the arc and energization occur at this time. The Joule heat generated by the current greatly affects the switching ability of the relay
2. The action principle when the contact is disconnected. When the contact is disconnected and the load is cut off, dazzling sparks and arcs will be generated. The generated arc must continue until the arc voltage drops below the minimum arc voltage value. Produce greater damage. The different contact materials and the size of the contact gap directly affect the arc electron emission state and the difficulty of occurrence, so they are important influencing conditions that determine the arc
When selecting a power relay, the power supply voltage of the general control circuit can be used as the basis for selection. The control circuit should be able to provide sufficient working current to the power relay, otherwise the power relay pull-in is unstable.