What does transformer regulation measure?

What does transformer regulation measure?

• A. The change in secondary voltage from no-load to full-load expressed as a percentage of full-load voltage.
• B. The efficiency of the transformer at full load.
• C. The ratio of primary to secondary voltages under no-load.
• D. The loss in copper during full-load operation.

Answer: (A)

The key idea is that transformer regulation tells you how much the output voltage on the secondary changes when you go from no load to full load, due to the resistances and leakage in the windings. The correct choice describes this as the change in secondary voltage from no-load to full-load, expressed as a percentage of the full-load voltage. In practice, regulation is calculated as (V_no-load − V_full-load) / V_full-load × 100%. This captures how well the transformer maintains voltage under load. This isn’t about efficiency, which deals with losses in the transformer, nor about the turns ratio (the ideal voltage ratio set by the winding turns), nor about copper losses specifically. Those other concepts describe different electrical performance aspects, not how much the output voltage varies with loading.

The key idea is that transformer regulation tells you how much the output voltage on the secondary changes when you go from no load to full load, due to the resistances and leakage in the windings. The correct choice describes this as the change in secondary voltage from no-load to full-load, expressed as a percentage of the full-load voltage. In practice, regulation is calculated as (V_no-load − V_full-load) / V_full-load × 100%. This captures how well the transformer maintains voltage under load.

This isn’t about efficiency, which deals with losses in the transformer, nor about the turns ratio (the ideal voltage ratio set by the winding turns), nor about copper losses specifically. Those other concepts describe different electrical performance aspects, not how much the output voltage varies with loading.