Correct Answer - Option 2 : a load greater than the rated range in the existing transformer
Case 1: Connected load is less than the rating of a single transformer, then there is no need for the two transformers operated to be in parallel for such kind of load; one transformer will be sufficient and can run at reduced load.
Case 2: Connected load is equal to the rating of a single transformer, then there is no need for the two transformations to be in parallel for such a kind of load; one transformer will be sufficient and can run at full load.
Case 3: Connected load is more than the rating of a single transformer Then, there is a need for the two transformations to be in parallel for such a kind of load.
The transformers are combined to supply a load greater than the rated range in the existing transformer in parallel order.
When two or more transformers run in parallel, they must satisfy the following conditions for satisfactory performance.
a) Same voltage ratio
b) Same percentage impedance
c) Same polarity
d) Same phase sequence
If the transformers operated in parallel do not have equal percentage impedance, the load sharing between those transformers will not be in proportion to their kVA ratings.