When banked transformers are used, the voltage rating across all units must be __________.

• A. The same
• B. Different
• C. Some multiples
• D. Random

Answer: (A)

When banked transformers are used, the voltage rating across all units must be the same. This ensures that, when the units operate together, they share the applied voltage evenly and no unit is subjected to a higher or lower voltage than the others. In parallel operation, identical voltage ratings prevent circulating currents and uneven loading; in series, matching ratings avoids overvoltage on any single transformer. If the ratings differed, one unit could take more load or endure higher stress, leading to overheating or insulation problems. Therefore, keeping the same voltage rating for every unit keeps the bank safe and reliable.