Delta-Star or Star-Delta Transformation

[powersys]

star delta transformation

For balanced 3-ph ac circuit analysis, a delta-connected-load can be converted to be a star-connected-load. Is the theory applied to a delta-connected-source? Can we convert a delta-connected-source to a star-connected-source in circuit analysis? Thanks.

 

[hani51]

delta to star transformation

changing delta connected power sourse to star connected sorce will change the generated voltage and increase it by root 3
this is because the line voltage in star connection is a vector summation of two phases each phase is equal the output of the delta voltage.
to keep same voltages it requires to change windings connection point and to use part of it which will change winding specifications and it is clearly unlogical.

 

[Kral]

delta-star transformation

powersys,
Yes, Delta-Star transformations are perfectly valid for sources. Both the voltages and phases must be adjusted to provide the equivalent star (Wye) connection. Analysis is frequently easier if both the source and load are of the same configuration.
Regards,
Kral

 

[powersys]

star-delta transformation

powersys,
Yes, Delta-Star transformations are perfectly valid for sources. Both the voltages and "phases" must be adjusted to provide the equivalent star (Wye) connection. Analysis is frequently easier if both the source and load are of the same configuration.

How to adjust the "phases"? What is the values of θ1, θ2, and θ3 in the equivalent star-connected configuration as shown in the figure below?

 

[Kral]

wye-delta transformation

powersys,
You show 2 Theta3's. Lets assume that Theta2 is the one associated with Vbn.
Then
. Theta1 = 0
. Theta2 = -120
. Theta3 = -240
Note also that the Star Line to line voltage Vba leads the phase voltage Vbn by 30 deg, etc.
regards,
Kral

 

[powersys]

converting delta to star configuration

powersys,
You show 2 Theta3's. Lets assume that Theta2 is the one associated with Vbn.
Then
. Theta1 = 0
. Theta2 = -120
. Theta3 = -240
Note also that the Star Line to line voltage Vba leads the phase voltage Vbn by 30 deg, etc.
regards,
Kral

Corrected Version:

So there is no 'phase shift' between Vab (delta configuration) and Van (star configuration) after the conversion?

 

[neils_arm_strong]

delta star coonection

Of course!.The interchange from delta to star is possible.It can be used in network theory.

 

[Nimer]

star versus delta

hi
guyes y - delta transformation is used to start three phaes induction motors to limit the starting current .


regards

 

[midolasi3]

explanation of star delta transformation

i think it's better to change all the delta sources and loads to the wye connection & solve the circuit in single phase mode is easily then you should apply the laws there to convert it back into 3 phase delta connected mode