The effect of laser treatment on the mechanical and electrical properties of busbar joints

A high proportion of the faults in electrical substations are due to the overheating of busbar joints. Surface contamination due to atmospheric corrosion is a main cause. Laser surface treatments have previously been applied by the authors to improve the surface hardness and corrosion resistance of aluminium alloys. Similarly, a chromium protective coating can be produced on copper by laser-alloying. This should allow more reliable bolt-together busbar joints to be made up on site with less attention to surface cleanliness. In this study, experimental investigations were made into the mechanical and electrical properties of laser-treated copper busbar joints under various conditions of applied torque and current flow. It was found that the maximum hardness of the laser-alloyed layer could reach HV95, which is almost 50% higher than that of the original sample. There were insignificant differences between the temperature distribution associated with the laser-alloyed and the untreated samples. The corrosion resistance of the laser-alloyed sample is slightly better than that of the original sample in the salt spray corrosion test. The electric conductivity of the uncorroded laser-alloyed joints was only slightly lower than that of the uncorroded untreated joints.