When connecting transformers in parallel, which condition must be met for them to share the load properly?

For transformers to share the load uniformly when connected in parallel, several critical conditions must be satisfied. The requirement for the same voltage and frequency ensures that the output voltages are compatible and that the transformers operate effectively without causing circulating currents between them. This prevents potential overloads or overheating due to mismatched outputs.

When transformers have the same kVA rating, it facilitates balanced load sharing according to their rated capacities. If one transformer has a significantly higher kVA rating than another, it would take on more load, which could lead to inefficiencies and overheating.

The need for the same phase sequence ensures that all transformers behave identically in relation to the phase rotations of the voltage. Mismatched phase sequences can lead to incorrect operation and severe damage to the system.

Meeting all these conditions—same voltage and frequency, same kVA rating, and same phase sequence—ensures that the transformers can operate cohesively as a unit, distributing the electrical load evenly and safely. Therefore, the correct answer is that all of the above conditions must be met for proper load sharing among parallel transformers.