In distribution systems, common transformer bank types include three single phase transformers connected as a three phase bank, often in delta delta, delta wye or wye delta configurations, and single three phase distribution transformers with all windings on one core. Other bank configurations involve open delta for emergency or reduced capacity operation, and special arrangements like Scott connections for two phase to three phase conversion. When someone asks this question, they usually want to distinguish between three single phase units in a bank and one integrated three phase transformer.