Question:

Two transformers of identical voltages but of different capacities are operating in parallel. For satisfactory load sharing _______.

Show Hint

Per-unit = actual impedance × base MVA / base voltage² → helps standardize comparison!
Updated On: Jun 24, 2025
  • impedances must be equal
  • per-unit impedances must be equal
  • per-unit impedances and X/R ratios must be equal
  • impedances and X/R ratios must be equal
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is C

Solution and Explanation

Step 1: Transformer parallel operation basics.
When transformers work in parallel, their voltage ratios, phase sequence, and impedances determine how they share load.
Step 2: Load sharing criteria.
If physical impedances are equal but transformer capacities are different, load sharing will not be proportional.
To ensure proportional load sharing:
- Per-unit (pu) impedance should be equal (based on kVA rating).
- X/R ratio (reactance to resistance) should also match to maintain correct power factor sharing.
Step 3: Why both?
Equal pu impedance → proportional sharing.
Equal X/R → same power factor, avoids circulating currents.
Conclusion: Both per-unit impedance and X/R ratio must match.
Was this answer helpful?
0
0