Which statement best defines polarity in transformers?

• A. Indicates the direction of current flow between windings
• B. Identifies the positive and negative bushings
• C. Shows the step-up or step-down ratio
• D. Indicates which bushing is north or south

Answer: (A)

Polarity describes the instantaneous relationship between the windings’ voltages. The ends marked with dots or symbols show which end of a winding is at a higher potential at the same instant, so you know how the voltages will add or subtract when windings are connected and which way current will flow in the windings for a given connection. This helps ensure correct phasing and prevents circulating currents or reversed operation when windings are tied together. So polarity effectively tells you the direction of current flow between windings based on how the windings’ voltages relate in time. The other points aren’t about this phase relationship: polarity isn’t about identifying bushings, the voltage ratio (step-up or step-down), or which physical bushing is north or south.