change wye-delta to wye ground-wye ground bank

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skywalker

New member
Location
Cebu City
Good am..

we are currently using 14400 : 120/240 transformer with Y-delta bank.. now we are to reconfigure it to Y ground - Y ground bank.. what are the possible ways to provide secondary 240 volt 3-phase power to a load if we are to use same transformer for the said Y g-Y g bank??? thanks..

pls justify..
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
Do you have a bank of 3 single phase transformers (14400 to 120/240) being used to create a delta secondary?

Is your goal to re-configure these transformers to get a wye secondary, but keep the 240V secondary voltage?

-Jon
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
You can't get 3 phase 240 out of a wye connected transformer bank unless you use non-standard transformers, and if you do that that line to neutral voltage would be 138 volts.
 

Cold Fusion

Senior Member
Location
way north
Good am..

we are currently using 14400 : 120/240 transformer with Y-delta bank.. now we are to reconfigure it to Y ground - Y ground bank.. what are the possible ways to provide secondary 240 volt 3-phase power to a load if we are to use same transformer for the said Y g-Y g bank??? thanks..

pls justify..
I'm just guessing since you didn't tell us: The transformer secondary coils are being reconnected as a 208/120, 3ph, grounded Y.

If that is so, then your options to provide 240V 3ph are either an autotransformer, or a 208D/240D transformer .

cf
 
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winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
A less common option would be to keep the secondary in a delta configuration, and then add a zig-zag grounding transformer. This creates a system that mimics a wye source quite well.

This all depends upon what the original poster is trying to achieve; what is the expected load current and the expected neutral current, etc.

-Jon
 

Smart $

Esteemed Member
Location
Ohio
...

This all depends upon what the original poster is trying to achieve; ...
That is THE question. I for one can't imagine a viable purpose for changing the secondary from delta to wye if it already is a 240V 3? system (seems logical to me, anyway ;)).
 

cripple

Senior Member
change wye-delta to wye ground-wye ground bank

If the existing system is currently a Delta 240 three phase 120 single secondary, the system cannot be reconfigured to provide a grounded 240/ 120 three phase. In a Delta system the phase to phase voltage is equal the winding voltage. If the 240 winding were connected in a wye the phase to phase voltage would be 415 volts and 240 volt to neutral or ground.
If the winding voltage is 120 volts then the phase to phase voltage would 208 volts.
 
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