I need to temporarily power up some 400 Volt equipment before it ships to Europe. I have access to a 480 to 400 volt auto-transformer but I read on temcotransformer.com's website that "Auto transformers should not be used in closed delta connections or they will introduce into a circuit a phase shift which causes higher power use."

My plants electrical supply is a 480 volt ungrounded delta. I have not been able to find any additional information on this subject. I was wondering if anyone has any knowledge about this.

If the worst issue is a small increased power use I'm not too concerned as this is only temporary. I would just like to know how much increased power and if there are any other issues to consider.

As long as the kVA is correct you should not have any issues if you are discussing a factory assembled auto transformer.