Why Does Contact Overheating Occur In High-voltage Disconnect Switches?

Overheating of equipment high voltage isolator is a common abnormal phenomenon. When operators use infrared thermometers, they often observe a significant temperature rise at the connection between the moving and stationary contacts. This temperature rise is not within the normal design parameters and indicates an internal physical or electrical problem.

The temperature rise factor affecting high voltage isolator switch originates from the change in contact resistance. When there is an oxide film, contaminant accumulation, or loose mechanical connection parts on the contact surface between the hv isolator contact and the contact finger, the impedance of the current passing through this interface will increase. This local impedance unevenness increases the proportion of electrical energy converted into heat energy, causing the contact temperature to rise. Defects in the metal contact surface coating of hv isolator switch and mechanical fatigue caused by long-term operation can also change the initial set contact pressure, causing the contact resistance to rise continuously.