The importance of low dissipation factor insulation in metal-clad switchegear

Recent years have seen the advent and application of many new and valuable insulating materials. We have seen new applications for older materials and increased emphasis on certain insulating properties such as surface track resistance and operation at higher temperatures. These new materials and new applications should provide the users of high voltage equipment with electrical apparatus which is more reliable and which requires less maintenance. However, this can only be achieved through careful study and control of all of the properties of the insulating material important to the application. For example, care must be exercised to insure that good surface tracking resistance of an insulation is not achieved at the cost of other dielectric properties. A material application, or substitution, without sufficient study of all of the properties can create new problems and in some cases provide a dielectric structure more prone to failure even though "improved" materials are applied. One important property, insulation dissipation factor, (often called power factor), whose neglect may lead to insulation failure in a number of ways, has been under study and control in the application of insulation to switchgear for a number of years. This report will deal with that activity.