Mechanical Tests for Materials used for Achievement of Breaking Electric Contact for High Currents

Breaking electric contact has been made for closing the circuits, respectively for taking over the temporary current conduction or for the long time conduction also for re-opening the closed electric circuit, putting out the current in this way. Although the contacts are the small parts of equipment volume in which they were mounted, there are complex exigencies and obviously different from case to case. For meeting these requirements, the electric contact must have the following properties: -high thermal and electrical conduction; -resistance to corrosion and material transfer due to electric arc between the contacts when opening and especially closing the circuit; -wearing resistance; -low and constant value of elasticity all time of operating. There is no material complying entirely with the main requirements of electric contacts for switchgear, that’s why the choosing of adequate contact material for each application imposes a compromise between the wished properties and the limit properties of materials.