Historical
IEC 62199 Ed. 1.0 b:2004
Bushings for d.c. application
Applies to outdoor and indoor bushings of any voltage used on d.c. systems, of capacitance graded or gas insulated types for use as components of oil-filled converter transformers and smoothing reactors, as well as air-to-air d.c. bushings.
International Electrotechnical Commission [iec]