Recent advances in superconducting wire technology, together with economic advantage of superconducting magnets to produce high magnetic field, have stimulated increasing interest in large scale superconducting apparatus such as superconducting magnet energy storage in electric power systems, superconducting magnets for fusion reactors and superconducting power generators. Electrical insulations may become one of critical design factors because high voltages are produced by stringent energy discharge and quenching in large superconducting magnets. In this review, abnormal overvoltage, performance of coolant liquids under high electric field and dielectric performance of insulating components in superconducting apparatus are described.
