If one transformer in a closed delta bank is removed, what percentage of the original capacity can the remaining two transformers handle?

In a closed delta transformer bank, when one transformer is removed, the remaining two transformers can continue to operate and provide power. However, the capacity is not simply halved because of the way the closed delta configuration works.

In this arrangement, three transformers are connected in a triangular format, and each transformer carries a fraction of the total load. When one transformer is taken out of the circuit, the load is redistributed between the remaining two transformers. Each transformer can still manage a portion of the load, but the capacity is reduced due to the loss of one of the transformers.

Mathematically, the capacity of a closed delta bank with two functioning transformers becomes about 58% of the original capacity. This calculation is based on the fact that each of the two remaining transformers can still handle the load but will experience additional stress due to carrying more of the total load than they were originally designed for.

This is why the correct percentage of the original capacity that the remaining transformers can handle is 58%. It reflects the operational efficiency and capacity limits of the remaining transformers in that configuration, ensuring they can handle an increased load without exceeding their rated capabilities.