This test method covers a means of testing the surface insulation resistivity of single strip of flat‐rolled electrical steel under predetermined conditions of voltage, pressure, and temperature.
Ten stainless steel contacts of fixed area are applied to one of the surfaces of the specimen at 300PSI Pressure and electrical contact is made with the base metal by two drills. The effectiveness of the surface insulation is then indicated by a measurement of average electrical current flowing between the contacts and the base metal under specified applied voltage. This measurement can be used directly as an indicator of insulation quality or may be converted to an apparent surface insulation resistivity as displayed in result
Scope of Measurements
Surface insulation resistivity is evaluated from a dc current that can range from 0 (perfect insulator) to 1 A (perfect conductor).