This guide concerns transformer connections in 3-phase distribution systems. Distribution systems are characterized by primary voltages up to and including 34.5 kV, usually have a preponderance of connected transformers with low voltage windings below 1000 V and furnish electric service to consumers. The characteristics of the various transformer connections and possible operating problems under normal or abnormal conditions are treated. All combinations of and Y, grounded and ungrounded, T connected, zigzag, and certain special connections are considered. Only two-winding transformers are included.Phasing procedures and loading practices are not covered. Guides for loading of oil-immersed and dry-type transformers are available in publications of the American National Standards Institute: American National Standard C57.91-1974, Appendix to C57.12.00-1973, Guide for Loading Mineral Oil-Immersed Overhead-Type Distribution Transformers with 55 C or 65 C Average Winding Rise; American National Standard C57.92-1962, Appendix to C57.12 Standards, Guide for Loading Oil-Immersed Distribution and Power Transformers; and American National Standard C57.96-1959, Appendix to C57.12 Standards, Guide for Loading Dry-Type Distribution and Power Transformers, respectively.
Abstract
New IEEE Standard - Active.The characteristics of the various transformer connections and possible operating problems under normal or abnormal conditions are treated for three-phase distribution systems. These systems are characterized by primary voltages up to and including 34.5 kV, usually have a preponderance of connected transformers with low-voltage windings below 1000 V, and furnish electric service to consumers. All combinations of Delta and Y, grounded and ungrounded, T connected, zigzag, and certain special connections are considered. Only two-winding transformers are included. Phasing procedures and loading practices are not covered.
