Induced voltage analysis with adjacent phases of the three-limb and five-limb trasnformers

Voltage at the interrupted windings that was induced with adjacent two phases of the windings was analyzed. There are three-limb and five-limb core type of three phase transformers typically. MOF is one of the three-limb transformers and power transformer is five-limb type in KEPCO distribution systems. In the three-limb transformers 100% of the rated voltages were induced and the load that connected outage phase could be supplied with two sound different phases so the transformers could be overloaded. The over loading failure case was presented. In the five-limb transformers the induced voltages were about 80% of the rated voltage at no-load condition but the load power couldn´t be supplied because of the outer limb that makes leakage flux linking phase to phase windings. The induced voltages depend on the core types but the voltage rate of primary and secondary at the outage windings is constant. The windings condition can be checked by the voltage ratio.