A quicker and reliable screening method for thermal classification of insulating materials

Correct knowledge of the thermal class of insulating materials is very important for efficient and optimal application in electrical equipment. Methods recommended in specifications (e.g. IEC-216) for evaluation of the thermal class need a long duration of about ten months. Often it is not convenient to wait for such a long period. Furthermore the specified method also requires a large quantity of energy, man hours and samples, and is expensive. Therefore, there is a need to develop a quicker but reliable method which at least can be used for screening purposes. This will enable the insulating material manufacturer to develop better material in a shorter time and users to identify appropriate material among a variety of insulating materials available on the market. The advent of modern analytical tools e.g. Thermogravimetric analysis (TGA) provides an appropriate tool in this regard, Several attempts hare been made in this direction. The three major approaches namely, DiCerbo, TPS and Toop methods have some limitations. In the proposed procedure an attempt has been made to overcome previous short comings. This method suggests that activation energy only in the degradation zone shall be considered for the evaluation. The observed results have shown good correlation with data observed from conventional method