Paralleling coils of common core 3 phase Transformer

[bulllymann]

Transformer is 15 kVA 600 delta/240 delta 3 phase dry core common core transformer. I would like to parallel the 3 - 240 volt secondary coils and input 240 volt single phase to output 600 volt single phase also paralleling the high side coils using the 3 phase transformer as a single phase step up transformer. Question: would paralleling all 3 coils both high and low side have issues due to sharing a common core? I know paralleling is easily done with 3 separate single phase transformers, but does the shared core create any kind of negative issues or harmonic? I hope I have explained this well enough. Many thanks in advance for answers.

 

[jim dungar]

You cannot connect the factory three phase delta windings into parallel single phase connection on a common three legged core.

I would not be surprised to find a 15kVA three phase transformer was made using a T connection of two windings.

 

[winnie]

You need to know the core arrangement and analyze the specific magnetic circuit.

Consider a delta:delta transformer on a 3 leg core. I don't see being able to parallel all three coil sets at full voltage without saturating the core. If you properly respect polarity, you could possibly parallel two of the coil sets.

However i think you would need to flip connections which might be welded in normal transformers.

And if it is a two core T arrangement all bets are off.

Jon

 

[bulllymann]

You need to know the core arrangement and analyze the specific magnetic circuit.

Consider a delta:delta transformer on a 3 leg core. I don't see being able to parallel all three coil sets at full voltage without saturating the core. If you properly respect polarity, you could possibly parallel two of the coil sets.

However i think you would need to flip connections which might be welded in normal transformers.

And if it is a two core T arrangement all bets are off.

Jon

Many thanks, This is what my concern is. I will have to experiment.