Preparation and Characterization of Polymer Fiber and Cellulose Composite Paper for Electrical Insulation

Abstract

With growing capacities, an ever-increasing reliability of products in service is demanded of power transmission systems. The life of transformer depends upon the insulating material used. The most important insulating materials of optimum dielectric strength properties that have been used in large high-voltage transformers through almost a century are the oil impregnated, cellulose-based products: primarily paper and pressboard. The chief disadvantage of cellulosic material for electrical use is that it is hygroscopic in nature and needs to be processed and maintained dry. For power transformers the process is quite elaborate and time consuming. To overcome this limitation, a new area to look forward to is blending of cellulose fibres with synthetic fibres. The most important property of these materials is their high thermal stability. Their dielectric strength is excellent, being above that of kraft paper, and they retain this property for a sustained period even at high temperature for short periods of time. This work discusses the production of electrical grade paper from kraft pulp and synthetic fibres. The insulation paper produced by blending kraft pulp with synthetic fibres, viz, polypropylene and polyethylene terepthalate has higher tensile, tear, burst strengths as compared to normal kraft paper making it useful for electrical insulation in transformers.