Temperature Index of Electrical Insulations by mTGA

摘要

Temperature index (TI) is a common measure for the temperature classification of electrical insulation materials (EIMs) used in electric machines and apparatus. TI is generally obtained through accelerated life testing lasting ＞7-8 months at certified labs. This paper deals with a new life-testing method to determine TI using thermogravimetric analysis (TGA), more particularly, modulated TGA (mTGA), The method of estimating precision of the TI is also given. The testing time may be reduced to ＜15 h per test. The new concept simplifies the life equation for practicability. The new method is not a replacement of conventional life testing, but may be of particular utility for screening new EIMs and evaluating materials with a known TI, after minor changes in composition have been introduced to improve physical properties. It can be a recommended method once it has been verified over a suitable range of EIMs.