IEC 60343: Surface Discharge Testing — Insulation Tracking Resistance Under Humid Contaminated Conditions

How Surface Tracking Transforms Insulation “Skin Disease” Into Fatal Flashover

IEC 60343:1991 specifies tracking resistance testing under surface discharge conditions. Unlike the IEC 60112 CTI test (electrolyte + low voltage), IEC 60343 simulates the combined effects of high-voltage surface discharge + contamination — much closer to real outdoor insulator operating conditions.

The test applies 2.5–6 kV AC across the specimen surface in a salt-fog environment, observing whether a conductive carbonized track forms. Once tracking initiates: leakage current surges → localized heating → carbon track propagates → surface flashover. This is a mandatory type test for outdoor composite insulator shed materials.

TNLab — Untreated insulation surface “skin disease” develops into fatal “heart disease” — surface flashover.