If transformers are going to be banked, do they all have to be the same voltage rating?

• A. Yes
• B. No
• C. Sometimes
• D. Unknown

Answer: (A)

Banking transformers means tying multiple units to act as a single larger transformer. The voltage rating must be the same for all units in the bank. When voltages match, current can share evenly and the bank maintains consistent voltage regulation and protection coordination. If one unit has a different rating, circulating currents and uneven loading can occur, causing overheating, insulation stress, and potential protection issues. Matching voltage ratings keeps the bank operating safely, reliably, and as intended. Therefore, they all should have the same voltage rating.