Silver contact selection

A contact is the point of contact between two conductors through which an electric current can pass. It is the source of the sound we hear when we press the switch.Contacts are as important to switches as safety is to our lives.So what kind of switch contacts are safe?We can distinguish it in two ways.The contact material is important.At present, there are mainly three kinds of contacts, namely, silver nickel alloy, silver cadmium alloy and pure silver. The conductivity of pure silver is indeed good, but the quality of pure silver is soft, and it is easy to deform after much operation. Moreover, due to the characteristics of easy oxidation, the conductivity becomes poor and heat is generated.Some companies also make switches that touch a thin layer of silver, posing a serious safety hazard.Silver-nickel alloy is an ideal contact material at present, which has the advantages of excellent resistance to welding and arc erosion and long service life.The contact of silver-cadmium alloy is good in other aspects, but cadmium element is a heavy metal, which is harmful to human body on the one hand, and the fusion with silver is not ideal on the other hand. Small particles of cadmium metal will form on the surface of the contact, and the electric arc may be pulled out when conducting electricity.So generally good companies will use silver nickel alloy as the best choice for contact.And we can clearly tell the difference between a good contact and a bad contact, which is the sound: the silver nickel sound is crisp and loud, so we can also make a preliminary screening by identifying the sound of a switch.