wye-wye transformer

[ALXC]

Hi,

Could anyone tell me what is the effect of an open-phase in the primary of a wye-wye transformer (particularely 600/347 V / 208/120 V)to the secondary side.

Thank you

 

[waross]

You lose one phase of the secondary. If you have two phase or three phase loads connected on the secondary, they will back-feed to the missing phase on the secondary. The voltage that you will measure on the missing phase will be anywhere from zero volts to almost full voltage depending on the mix of single, two phase and three phase loads connected at the time of measurement.
yours

 

[ALXC]

Thank you waross, that clearly explains the situation I'm dealing with.