How Do You Connect A Three 250MVA Single Phase Transformer Into A Single 3Phase Transformer?
It is not uncommon to see three-phase transformer banks made up by interconnecting single-phase transformers. This is done for one of two reasons. 1. One reason may have to do with the power ratings. A three-phase bank has a power rating that is three times rating of the individual single-phase units (assuming that the single-phase units are equal). Therefore, an equivalent three-phase transformer would be about three times as large and three-times as heavy. There may be manufacturing, shipping, or installation limitations that favor using single-phase units instead of three-phase units. 2. The other reason is reliability. Failure of a three-phase transformer means that the entire transformer has to be repaired or replaced. But if the bank is made of up three single-phase units, it is possible to repair/replace on the one one failed unit. Often, when three-phase banks are constructed from large single-phase units, a fourth single-phase unit is purchased as a spare. This might be very a
