Contact material and arc current affect on post-current zero contact surface temperature

Optical radiation measurements of contact surfaces were made after current-zero of a high-current (>10 kA_p) arc, to determine how much the contact surface temperature at and after current zero was affected by a change in contact material and arc current. Contact surface temperature was measured for different types of "typical" contact materials (AgW and AgC) commonly used in molded case circuit breakers (MCCB\´s). The average temperature at the contact surface was measured by using photodiodes in conjunction with a narrow band filters and a long-range microscope. A 250 Amp rated MCCB was modified, with renewable chamber walls and contacts, and used as a test bed to insure that these results can be directly applied to MCCB\´s in the 125 to 250 Amp range. Uniform and repeatable arcing conditions were maintained by using an electronically timed capacitor bank source, timed contact part, and a well-maintained arc chamber. Along with other important engineering properties of the contacts (arc erosion, temperature rise), this data can be useful for selecting contacts for circuit breaker applications.