Determining D.C. voltage ratings of insulated conductors

The specification of proper voltage ratings for insulated wire and cable is determined from the properties of their insulating materials, material thickness and the environment in which the cable operates. In this paper, particular attention is paid to determining D.C. voltage ratings for insulated conductors and a review of industry standards shows that A.C. voltage ratings are abundant while D.C. Voltage Ratings have received little attention. The mechanisms for establishing voltage rating is presented with a discussion of Dielectric Breakdown Voltage, Voltage Stress Analysis, Temperatures and others, along with supporting charts and tables. Finally, a practical procedure is offered for establishing D.C. ratings. This approach allows the designer to calculate D.C. ratings from A.C. ratings, mathematically, using the formulas presented or selection can be made from the Table of Materials given at the paper´s end.