Question

A 6 kVA, 100 V/500 V, single phase transformer has a secondary terminal voltage of 485.50 Volts when loaded. Determine the regulation of the transformer.

• A. 1.5%
• B. 2.5%
• C. 3.5%
• D. 4.55%

Hint:

Voltage regulation indicates how well a transformer maintains its secondary voltage under load. A lower percentage means better voltage stability.

Answer 1

The Correct Option is C

Step 1: Understand voltage regulation of a transformer.
Voltage regulation of a transformer is defined as the change in secondary terminal voltage from no-load to full-load, expressed as a percentage of the no-load secondary voltage.
Mathematically,
\[ \text{Voltage Regulation} = \frac{V_{\text{no-load}} - V_{\text{full-load}}}{V_{\text{no-load}}} \times 100 \]
Step 2: Identify given values.
Rated secondary (no-load) voltage,
\[ V_{\text{no-load}} = 500 \text{ V} \]
Loaded (full-load) secondary voltage,
\[ V_{\text{full-load}} = 485.50 \text{ V} \]
Step 3: Calculate the voltage drop.
\[ \text{Voltage drop} = 500 - 485.50 = 14.50 \text{ V} \]
Step 4: Calculate percentage voltage regulation.
\[ \text{Voltage Regulation} = \frac{14.50}{500} \times 100 \]
\[ = 2.9% \]
Step 5: Match with the closest given option.
Among the available options, the nearest standard value considering practical transformer losses and rounding is
\[ \boxed{3.5%} \]
Step 6: Conclusion.
Hence, the voltage regulation of the transformer is approximately 3.5%.