A 200KVA transformer with a primary voltage rating of 7620 V would have _______ polarity.

• A. Subtractive
• B. Additive
• C. Negative
• D. Positive

Answer: (B)

Understanding transformer polarity comes from how the windings are oriented relative to each other. Each winding has a marked polarity with a dot at the end that stays in phase with the other winding when voltages are applied.

When the ends marked with the dots are connected in the same direction, the voltages add together in series. This is called additive polarity. For a transformer with a high-voltage primary like 7620 V, the windings are typically arranged so that the primary and secondary voltages align in the same phase, so they add when connected in series rather than oppose each other.

Subtractive polarity would occur if the windings were oriented so that their voltages oppose each other in series, yielding a smaller total voltage. Positive and negative aren’t the standard terms used to describe this phase relationship in this context; the key distinction is additive versus subtractive based on how the windings’ polarities line up.