Molded electrode test system for evaluating wet electrical performance of flexible poly(vinyl chloride)

The molded electrode test system (METS) test has long been used with flexible poly(vinyl chloride) (PVC) electrical insulation. However, there are many questions regarding its precision and accuracy, as there is no industry‐accepted standard regarding this test. This paper aims to answer some of these questions in terms of the measurement precision as well as the ability of the test to predict wet electrical performance on wire. A repeatability study was conducted on flexible PVC compound where 10 samples were produced and tested under identical conditions. The mean insulation resistance was (550 MΩ)/(305 m) with a standard deviation of (120 MΩ)/(305 m). As the thickness of the insulation increased, the insulation resistance decreased. Furthermore, the study showed that there was no correlation between the METS test and wet volume resistivity, while there was some correlation with wet insulation resistance (IR) at high temperature, though the ability to predict wet IR from the METS test was limited. J. VINYL ADDIT. TECHNOL., 18:178–183, 2012. © 2012 Society of Plastics Engineers