Three-Phase Transformer Application

You say "(240 volt) is needed," but you don't say which configuration you would like to have, such as 240 Y or ^.

A 2:1 step up/dn transformer connected to 480 Y will yield 240 Y.

Since you have a 480 Star system, you can install a step down transformer from 480V to 240V either in 3 phase 240V (Secondary Delta connection) or Single phase 240V (Secondary Star Connection).

Or you can install a 2 phase 480/240 step down transformer for single phase of 240V only.

It all depend on your choice of application.