What does the term Banked describe?

Two or three, single-phase transformers can be inter-connected to make a three-phase bank. The primary windings of the single-phase transformers can be connected in Delta or Wye. Likewise the secondary windings can be connected in either a Delta or Wye configuration.

The equivalent capacity of the bank will be equal to three times the nameplate rating of each single-phase transformer. Usually, this type of installation is more expensive than using a single three-phase transformer. Advantages to banked transformers include:

  • For utility applications, the loss of one transformer in a delta configuration creates an open delta configuration using only two transformers. This will continue to supply power albeit at a reduced total kVA rating.
  • Banked transformers can be used to applications where the size or weight of a three phase transformer is too large. An example would be the ability to move a banked transformer in three lighter and smaller sections in a freight elevator.