High potential testing is conducted to determine if the cables can withstand normal operating voltages as well as over voltage conditions. There are specific tests suitable for field-aged cables as well as for newly installed cables. It is important to conduct the appropriate test in order to obtain as much information regarding the electrical health of the insulation without imposing detrimental effects in the process. Improper testing can lead to unexpected expenses and delays.
Technicians will use an AC hipot test to confirm the integrity of insulation on service-aged cables. In other words, technicians who perform over-voltage testing with DC can unknowingly leave charges in voids of the insulating material. When the cable is placed back into service, these charges contribute in the partial breakdown of the insulation, and an accellerated rate of degradation. DC hipot testing is viewed more favorably for acceptance testing of new cables that have not yet developed water trees and other imperfections related to the introduction of contaminants found in service-aged cabling.
Related electrical test equipment available for rent from Protec:
Editor’s Note: This post was originally published on July, 2011 and has been updated freshness, accuracy and comprehensiveness.