How is the capacity of an open bank of transformers compared to the combined capacity of a closed bank?

In the context of transformers, the capacity of an open bank of transformers can often differ significantly from that of a closed bank. A closed bank refers to a situation where all transformers are fully connected and utilized, allowing for maximum efficiency and output. However, an open bank typically refers to a scenario where at least one transformer is disconnected or not operational, leading to a decrease in the overall capacity.

For open banks, the generally accepted figure for capacity compared to a closed bank is often around 57.7%. This percentage reflects the impact of having fewer transformers engaged in supplying power, which limits the system's total output relative to when all transformers are functioning optimally.

The reasoning behind this specific figure involves the consideration of load sharing among operational transformers. With fewer transformers in an open configuration, each transformer must bear a greater share of the load, and inefficiencies come into play as capacity diminishes due to additional losses in the system. Hence, 57.7% accurately represents the capacity of an open bank compared to a closed bank under these operational conditions.