Contact heating by long arcing during connector disconnection

The increasing demand of electrical power in vehicle needs either higher voltage or current levels are well-known as the origin of long arcing in switching and connecting devices. The subsequent contact damage such erosion and surface degradation is due to the over heating of the contact during the transfer of an amount of arc energy to the contact. In this paper we investigated conjointly the temperature profile of the arc and the contact during the arc. A diagnostic method using fast infrared device (1Ksample/sec) for contact temperature and spectroscopic streak mode (300Ksample/sec) for arc temperature was achieved. When applied to long arc during disconnection at low speed, we have found that arc temperature is close the well known value of the plasma i.e. few thousands °K. However the contact temperature increases during the energy transfer from arc to the contact and takes maximum value at the arc extinction. We can note that melting temperature of the coating (Sn) and base material (Cu) are reached in the case of long arc at low current or at shorter arc at higher current. Finally we can conclude that this thermal analysis give a clear explanation of the insertion force after arcing and constitute an useful and direct tool rather than arc electrical parameters for contacts degradation characterizations.