A practical study on electrical contact resistance and temperature rise at at the connections of the copper busbars in switchgears

Electrical contact resistance plays an important role in temperature rise of switchgear busbars. This experimental study has been conducted to establish a practical thermal design technique for the bolted connections between copper busbars in switchgears. For this study, overlap length, contact pressure, nut factor, temperature, and arrangement of the connections were considered as test parameters to determine the contact resistance. Silver plated copper busbars were mainly used for the test specimens but the contact resistance between naked busbars was also tested to investigate the silver plating effect. Temperature rise at the busbar connection due to the contact resistance has been analyzed with the tests of the contact resistances and a numerical thermal simulation in this study.