What are the materials of relay contacts

The Silver contacts for the Relay are in a normally open or normally closed state, which is to say that the contacts that connect or disconnect the signal when the switch is normally open or normally closed are called the contacts of a relay.

The Solid Silver Contact Rivet is one of the most important components of an electromagnetic relay. The performance of the contact is affected by factors such as contact material, contact pressure, load type, operating frequency, atmospheric environment, contact configuration, and beating. Supposef any of these factors cannot meet the predetermined value. In that case, point contact problems such as metal electrochemical corrosion between contacts, contact welding, wear, and rapid increase in contact resistance may occur. The rated load of the contact refers to the voltage and current that the electromagnetic relay is allowed to disconnect. The size of the load determines the size of the voltage and current that the electromagnetic relay can control. Electromagnetic relays cannot exceed these two values ​​during use, otherwise, it will easily cause damage to the relay Solid Ag Contacts.

There are three types of contact forms: point contact, line contact, and surface contact. As far as electromagnetic relays are concerned, the contact form of the contact is mostly Silver Contact Points. Common electromagnetic relays on the market have one set of contacts, two sets of contacts, and three sets of contacts. To ensure that the contact itself did not accidentally fail due to quality problems during the experiment, and to ensure that the contact pressure was detected in the largest space, the electromagnetic relays with one set of contacts and three sets of contacts were abandoned during the experiment. The electromagnetic relays with two sets of contacts were selected.

In the energized state, when the Moving Silver Contact and Flat Bimetallic Rivets are out of contact, if the current of the disconnected circuit exceeds a certain value (different relays have different contact materials and different rated currents), or the voltage applied to both ends of the contact gap after disconnection exceeds a certain value (different relays have different contact materials and different rated voltages), an arc will be generated in the contact gap. The arc is a discharge phenomenon generated by the gas between the contacts under a strong electric field, which produces high temperatures and emits strong light and sparks. The existence of the arc not only burns the metal surface of the contact, reduces the life of the electrical appliance, but also prolongs the circuit disconnection time, and even causes the relay contact to fail. In severe cases, it can cause fire or gas accidents. Therefore, to accurately detect the changing law of contact pressure, it is necessary to ensure that the current disconnected by the electromagnetic relay and the voltage applied to both ends of the relay contact cannot exceed the rated value during the experiment.

Common relay contact materials are pure metal, metal alloy, and metal-ceramic (powder metallurgy). The Electric Contacts for PV Relay capacity are related to the material. Generally, copper or silver plating is used. Gold plating is used for contacts with low on-resistance. Tungsten is used for high current and high intensity. Of course, there are other alloy materials, all related to the application (capacity, withstand voltage).

Electromagnetic relays use the "on" and "off" of contacts to control the circuit. The contact voltage drop caused by the difference in contact resistance between contacts is different. The greater the contact resistance of the contact, the greater the voltage drop on the contact. The resulting impact is:

1) Increase contact heating and shorten the service life of the contract;

2) Reduce the effective voltage on the load.

To avoid the above effects, it is required to reduce the contact resistance of the Cap Head Silver Contact as much as possible. Materials with good conductivity should be selected. Commonly used materials are: copper, silver, and silver has better conductivity than copper.

For small relays used in small signal circuits, copper contacts with gold plating on the surface can also be used, as the control current is small and the Gold Plating Contact surface is small.