Electrical Engineering ⇒ Topic : Solving Unbalanced 3Wire Y Load by Y/delta Conversion

April
 
Solving Unbalanced 3Wire Y Load by Y/Δ Conversion Fig. (a) shows an unbalanced 3wire Yconnected load while Fig. (b) shows the equivalent Aconnected load. It was shown in chapter 3 that Y connection of resistances can be replaced by an equivalent Δ and viceversa. With a.c., the same formulas hold good except that resistances are replaced by impedances (in complex form) (a) (b) figure Thus the Yload of Fig. (a) can be replaced by equivalent Δload having branch impedances The equivalent A load can be solved to obtain the line currents. The line currents so calculated will be the line currents taken by the original unbalanced Yload. How to remember above relations ? The symmetry of above relations shows that one should not try to memorise them. It may be seen that numerator is the same in the three cases i.e., it is the sum of the cross products of star impedances viz. Z_{1}Z_{2 }+ Z_{2}Z_{3 }+ Z_{3}Z_{1.} However, denominator is that star impedance which is not included in the considered terminals. Thus, for Z_{12}, the terminals are 1 and 2 and the star impedance not included in these terminals is Z_{3}. Hence in this case Z_{3} is the denominator.  
 
!! OOPS Login [Click here] is required for more results / answer