Conditions for Parallel Operation of 3Φ Transformer.
Q. State various conditions for parallel operation of 3Φ transformer.
Conditions :
- Voltage ratings of the primary windings should be suitable for supply system voltage and frequency.
- The windings must be properly connected as regards their polarities.
- Voltage ratings of primary and secondary of both transformers must be identical (i.e. they should have same turns ratio or voltage transformers ratio).
- The per-unit or % impedances of both should be equal in magnitude and have same X / R ratio to avoid circulating current.
- kVA ratings of both may be same, but if not, then their % impedances should be inversely proportional to the individual kVA ratings to avoid circulating current.
