High-voltage testing fundamentals: a cable testing perspective

An ever-increasing appetite for electrical energy by industrial, commercial, and household consumers has resulted in a continuously growing demand for transmission capacity and improved reliability of elecricity supply. The reliability of a HV power plant must be maintained at a high level over its lifetime, typically 50 years. All newly manufactured components of electricity networks undergo various types of tests to ensure their reliability and longevity. The tests follow specifications set out in national and international standards. These tests could be described in general terms as: design-verification tests,; production-quality tests, and ; tests after installation. Of all systems in a HV plant, cable systems must satisfy possibly the widest range of test requirements. So in this article we use electrical testing of cable systems to show the origins of the main test specifications. Although we refer throughout the paper mainly to cables with extruded insulation and their accessories, most of the discussion can be generalized to other HV equipment such as power transformers or insulators. We limit our discussion to insulated cable systems built to transmit electrical power in bulk at the subtransmission and transmission voltage levels, i.e., those rated above 30 kV.