Oil-Immersed HVDC Converter Transformers (This standard specifies the electrical, mechanical and physical requirements of oil-immersed single-phased and three-phased converter transformers.). New IEEE Standard - Superseded. Superseded by IEEE Std C57.129-2007. The electrical, mechanical, and physical requirements of oil-immersed single-phase and three-phase converter transformers are specified in this standard. Tests are described and test code defined. Devices such as arc furnace transformers and rectifier transformers for industrial or locomotive applications are not covered.