Contact action principle of power relay

The action process of the contact can be divided into two parts: contact closing and contact opening, that is, the pull-in and release process of the relay. They cyclically switch at a certain frequency to form the contact opening and closing phenomenon. During the process of contact closing and opening, there will be many special physical and chemical phenomena, such as contact resistance, contact jitter and arc.
The action principle when the contact is closed:
When the moving contacts and static contacts of the relay touch each other, contact bounce will occur, that is, uncontrolled intermittent opening and closing. The arc generated at this time and the Joule heat generated by the energizing current will greatly affect the relay. opening and closing ability.
The action principle when the contact is open:
When the contact is disconnected and the load is cut off, dazzling sparks and arcs will be generated. The arc will continue until the arc voltage drops below the minimum arc voltage value, which will cause greater damage to the contacts. Different contact materials and contact gap sizes directly affect the emission state of arc electrons and the ease of occurrence, so they are important influencing conditions that determine the arc.