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Electrical contact phenomenon

Electrical contact phenomenon

The electrical contact material mainly includes the on process, on state and off process in the working process, and different electrical contact phenomena will be generated in these processes.

Turn-on process

Electrical contact material in the process of turn-on electrical contact phenomena includes arc erosion and dynamic fusion welding.

Turning on the circuit is one of the important functions of electrical contact materials.

In the connection process, when the distance between two contacts with a potential difference is very close, the gas in the gap is ionized, changing from insulator to conductor, arc discharge occurs, and the electric contact material produces local high temperature and even arc erosion.

At the same time, the collision between the dynamic and electrostatic contacts will also cause mechanical wear and tear and even bouncing, so that the arc time is extended. In this way, the electrical contacts will form a large impact current, in a short period on the electrical contact material that occurs continuously, multiple times, thus causing the electrical contact material “dynamic fusion welding”.

In the process of turning on, the arc duration is very short. As the gap between the electrical contacts shortens, the discharge occurs due to the pre-breakdown of the gap, which causes the material to fuse or evaporate, and then causes solid-state contact .

Turn-on state

The electrical contact phenomena occurring in the electrical contact material during the turn-on process are the change in contact resistance and static fusion welding.

In the on state, the electrical contact material is part of the circuit and plays the role of fixed contact, current carrying, electrical energy transfer, and signal transmission.

Therefore, the electrical contact material should have a low and stable contact resistance and not change much with the environment. Contact resistance generated by the Joule heat effect is serious, will lead to electrical contact material melting and cause electrical contacts welded together, known as “static fusion welding”.

When the fusion welding force exceeds a certain value, the electrical contacts cannot be separated, i.e., the circuit should be disconnected but can not be successfully achieved, causing the circuit can not or delayed disconnection, resulting in disconnection failure .

Disconnection process

The electrical contact material in the disconnection process occurs as an electrical contact phenomenon mainly by arc erosion. Disconnection of the circuit is also the main function of the electrical contact material.

If the voltage supplied to the electrical contact and the current flowing through the electrical contact exceeds the critical value, an arc will be ignited when the electrical contact breaks the circuit.

In electrical contacts from the contact on position to the direction of disconnection, the contact force must gradually reduce, and the actual conductive surface area will gradually reduce, increasing contact resistance.

In the moment of the final separation of the contact surface, the heat generated by the resistance will be concentrated to the last point of departure in a very small range, so that its temperature rises rapidly to the melting point of the metal or even boiling point, which may cause explosive vaporization; in the electrical contact gap filled with high-temperature metal vapor, the contact will form an arc between the contacts, the resulting arc heat acts on the surface of the electrical contact material, so that the electrical contact material phase change, arc erosion, transfer The melt pool splash and other complex physical and chemical processes.

This will cause the electric contact material to be eroded and lost by the arc, which may lead to electrical contact material electrical contact failure .


Hello, my name is Eva Xia, and I am currently the Marketing Manager at Yueqing Weup Technology Co., Ltd, located in Wenzhou, Zhejiang, China. With over a decade of experience in the accounting field, I have developed extensive knowledge and skills that enable me to excel in my role. Additionally, I have spent two years working as an English teacher, which enhanced my communication abilities and instilled discipline within me.

Having gained more than three years of valuable experience in overseas sales, I have had the opportunity to expand my horizons and develop a deeper understanding of the commercial landscape. This exposure has nurtured my business understanding and allowed me to navigate diverse markets confidently.

However, despite my accomplishments thus far, I remain dedicated to continuous growth and learning. My current area of focus revolves around electronic switches. It is a fascinating and dynamic field that constantly evolves with technological advancements. By delving deeper into this realm, I aim to enhance my professional knowledge and stay ahead of industry trends.

In summary, as a Marketing Manager at Yueqing Weup Technology Co., Ltd., I bring forth a wealth of experience in accounting coupled with the valuable skills honed during my time as an English teacher. Furthermore, my extensive overseas sales expertise has sharpened my business acumen. With a relentless thirst for knowledge and a specific interest in electronic switches, I strive to enhance my professional capabilities further while contributing positively to our organization’s success.

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Eva Xia,
Marketing Manager at Yueqing Weup Technology Co., Ltd

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