High voltage tracking resistance (IPT)

This method is used to assess the susceptibility to tracking of insulating materials that are exposed to high voltages outdoors.

Insulators installed in the open are often at the mercy of humidity. Their electrical insulation properties can deteriorate to such an extent as a result that tracking paths are formed on the insulator surface. This test determines the tracking resistance that defines the dielectric strength of the insulating material surface and the maximum allowable leakage current (tracking).



Test specimen 130 mm x 50 mm x 6 mm
Test voltage between 1,0 kV and 7,0 kV (in 250 V steps)
Test solution 0.075 ml/min at 1.5 kV
0.15 ml/min at 2.5 kV
0.30 ml/min at 3.5 kV
0.60 ml/min at 4.5 kV
Failure criteria Method A:
  • Current exceeds 60 mA
  • Specimen burns
  • Hole is formed
Failure criteria Method B:
  • Tracking reaches mark (25 mm)
  • Specimen burns
  • Hole is formed
  • Current exceeds 60 mA


High voltage tracking resistance (IPT) High voltage tracking resistance


Results of the test method:The maximum test voltage at which five specimens each resist the stress for six hours without any of the failure criteria being met.