Given: A three phase three-wire delta system carrying 19,920 volts line-to-line, is cut over to a three phase four-wire WYE system using the same transformers. What is the resulting line-to-line voltage?

Given: A three phase three-wire delta system carrying 19,920 volts line-to-line, is cut over to a three phase four-wire WYE system using the same transformers. What is the resulting line-to-line voltage?