Transformer Voltage Ratio Calculation Explained

This question asks us to find the voltage transformation ratio for a transformer given the number of turns on its primary and secondary windings.

Understanding Voltage Transformation Ratio

The voltage transformation ratio (often denoted by $k$) in a transformer indicates how the voltage changes from the primary winding to the secondary winding. It is directly proportional to the ratio of the number of turns in the secondary winding ($N_s$) to the number of turns in the primary winding ($N_p$). The formula is:

$$ k = \frac{V_s}{V_p} = \frac{N_s}{N_p} $$

Where:

• $V_s$ is the voltage across the secondary winding.
• $V_p$ is the voltage across the primary winding.
• $N_s$ is the number of turns on the secondary winding.
• $N_p$ is the number of turns on the primary winding.

The transformer's kVA rating (25 kVA in this case) relates to its power handling capacity and is not directly needed to calculate the voltage transformation ratio based on turns.

Given Data

• Number of turns on the secondary winding, $N_s = 50$ turns.
• Number of turns on the primary winding, $N_p = 500$ turns.

Calculation Steps

To find the voltage transformation ratio, we apply the formula using the given number of turns:

1. Identify the number of turns for both windings: $N_s = 50$ and $N_p = 500$.
2. Substitute these values into the voltage transformation ratio formula:

   $$ k = \frac{N_s}{N_p} $$

3. Perform the division:

   $$ k = \frac{50}{500} $$

4. Simplify the fraction:

   $$ k = \frac{1}{10} $$

5. Convert the fraction to a decimal:

   $$ k = 0.1 $$

Final Result

The calculated voltage transformation ratio is 0.1. This value indicates that the voltage in the secondary winding is 0.1 times the voltage in the primary winding, meaning it's a step-down transformer.

Comparing this result with the given options, the correct answer is 0.1.