Feature article - Some of the considerations for materials operating under high-voltage, direct- current stresses

This article identifies the important electrical parameters that need to be measured and understood to establish the reliability of devices operating under DC voltages. Thus there is a strong economic and technical reason to understand and master the use of materials in HVDC applications. The basic electrotechnical data have been reported often, yet the ways in which they can be usefully combined have been addressed less frequently. This article addresses the ways in which the data might be used under DC conditions. A description then is provided of how the electrotechnical data can be combined in a coherent manner to enable estimates to be made of the device reliability. Typical data for a range of insulation classes have been extracted from the sources available and are presented here to illustrate the calculations. Areas of further useful work also are identified.