Maximum allowable unbalance on LV transformer

[Nomyelectric]

I need to know what is maximum unbalance (total Load) is OK without any trouble to a 3-phase LV transformer.
I have 30KVA Delta-star (480/380/220) Transformer, on which only a single equipment of three phase 380V- 20KW is connected, and I need to connect a single phase (220V- 3.3KW load on any of the phase on star/secondary.
Is that unbalance is allowable.
Thanks

 

[winnie]

Probably.

That one phase will be fully loaded but not overloaded.

The imbalance might impact voltage balance, and that could impact the balanced load

 

[jim dungar]

You can treat the secondary as if it was three single transformers, each with 1/3 the capacity of the full rating. In your case you have (3) 10kVA single phase transformers that can be loaded any way you want.