Which transformer winding is connected to the power line (source)?

Which transformer winding is connected to the power line (source)?

• A. Shield Winding
• B. Primary Winding
• C. Tertiary Winding
• D. Secondary Winding

Answer: (B)

In transformer operation, the winding connected to the power line is the primary winding. You attach the source voltage to this winding, and its changing current creates a magnetic flux in the core that links to the other windings. The energy then transfers by mutual induction to the remaining windings, producing the output on the secondary (and any auxiliary voltages on other windings, if present). The shield winding exists only to reduce capacitive coupling and noise between windings, not to carry the source power. The tertiary winding, when present, provides an additional, typically auxiliary, voltage and is not the main input. So the input side—the winding connected to the line—is the primary winding.

In transformer operation, the winding connected to the power line is the primary winding. You attach the source voltage to this winding, and its changing current creates a magnetic flux in the core that links to the other windings. The energy then transfers by mutual induction to the remaining windings, producing the output on the secondary (and any auxiliary voltages on other windings, if present). The shield winding exists only to reduce capacitive coupling and noise between windings, not to carry the source power. The tertiary winding, when present, provides an additional, typically auxiliary, voltage and is not the main input. So the input side—the winding connected to the line—is the primary winding.