Red Seal Electrician Practice
TransformersQuestion 1099 of 1506

A transformer diagram has no dots, but the leads are marked H1, H2, X1 and X2. What do the subscript numbers show?

  1. The number of turns on each winding, in order of the layers.
  2. The order of the tap positions along the winding.
  3. Winding polarity: the 1 leads are the dot ends.
  4. The rated current of each lead, from low to high.
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Correct answer: Winding polarity: the 1 leads are the dot ends.

When H and X labels are used, the numbers stand for polarity. The H1 and X1 leads are the dot positions.

Source: Lessons in Electric Circuits II: AC (Kuphaldt), 10.4: Phasing

Practice transformers

Questions last reviewed: 18 October 2026