Which transformer winding is connected to the power source?

Which transformer winding is connected to the power source?

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

Answer: (D)

The winding connected to the power source is the primary winding. In a transformer, energizing the primary with the input supply creates alternating magnetic flux in the core. This changing flux links to the secondary winding and induces a voltage that powers the load, with the turns ratio setting the voltage and current on the secondary side. Other windings serve different purposes: the secondary provides the output power; a shield winding sits between windings to reduce capacitive coupling and noise (usually grounded), and a guard winding is used to control leakage or shielding in some designs. None of these last windings are intended to deliver input power from the source.

The winding connected to the power source is the primary winding. In a transformer, energizing the primary with the input supply creates alternating magnetic flux in the core. This changing flux links to the secondary winding and induces a voltage that powers the load, with the turns ratio setting the voltage and current on the secondary side. Other windings serve different purposes: the secondary provides the output power; a shield winding sits between windings to reduce capacitive coupling and noise (usually grounded), and a guard winding is used to control leakage or shielding in some designs. None of these last windings are intended to deliver input power from the source.