Determine Transformer KVA output and Power Factor

Click For Summary
SUMMARY

The discussion focuses on calculating the KVA output and power factor of two transformers, T1 and T2, operating in parallel to supply a common load of 5500 KVA at a lagging power factor of 0.8. The per unit impedances of the transformers are given as Za = 0.04 + j0.09 and Zb = 0.01 + j0.07, both rated at 3000 KVA. The calculations reveal that the KVA output for T1 (Sa) is 2326 KVA and for T2 (Sb) is 1573 KVA, totaling 3899 KVA, which is incorrect due to an error in the impedance value used for Za. The correct impedance for Za should be 0.098 < 66.04.

PREREQUISITES
  • Understanding of transformer operation and parallel connection
  • Familiarity with complex impedance and phasor notation
  • Knowledge of power factor and its significance in electrical systems
  • Basic skills in electrical engineering calculations
NEXT STEPS
  • Review transformer impedance calculations and their impact on load sharing
  • Study the concept of power factor correction in electrical systems
  • Learn about the effects of lagging power factors on transformer performance
  • Explore advanced topics in electrical load analysis and phasor diagrams
USEFUL FOR

Electrical engineers, power system analysts, and students studying transformer operations and load calculations will benefit from this discussion.

maluzha
Messages
1
Reaction score
0
1. Two transformers T1 and T2 in parallel supply a common load at a lagging pf of 0.8, their per unit impedance are 0.04+j0.09 and 0.01+j0.07 at the same kva ratings of 3000KVA each and load power = 5500KVA

Determine the kva output of each transfromer and power factor

This is how i worked it:
Za=0.04+j0.09
Zb= 0.01+j0.07
Zt=0.05+j0.16

Za/(Za+Zb)= 0.048<66.04/0.168<72.65
=0.286<-6.61
Zb/(za+Zb)=0.071<81.86/0.168<72.65
=0.423<9.21
Sa=5500<-36.86*0.423<9.21 = 2326<-27.65
Sb= 5500<-36.86*0.286<-6.61 = 1573<-43.47

Sa+Sb gives a total of 3899kva which is wrong!
 
Last edited:
Physics news on Phys.org
Za should be .098<66.04

Why is it Za/(Za+Zb) don' understand this part.

Thanks
 
Za/Za+Zb is the ratio of Za to the total load
 

Similar threads

Archived Efficiency Calculation of 10-kVA Transformer at 0.85 Power Factor Lagging
  • · Replies 1 ·
Replies
1
Views
2K