Question

A transformer rated at 10 kW is used to connect a 5 kV transmission line to a 240 V circuit. The ratio of turns in the windings of the transformer is

• A. 5
• B. 20.8
• C. 104
• D. 40

Hint:

Turns ratio equals voltage ratio: \(N_p/N_s = V_p/V_s\).

Answer 1

The Correct Option is B

Step 1: Use transformer turns-voltage relation.
For an ideal transformer:
\[ \frac{N_p}{N_s} = \frac{V_p}{V_s} \]
Step 2: Substitute given voltages.
Primary voltage \(V_p = 5kV = 5000V\).
Secondary voltage \(V_s = 240V\).
Step 3: Calculate turns ratio.
\[ \frac{N_p}{N_s} = \frac{5000}{240} \approx 20.83 \]
Step 4: Match with option.
Nearest value is \(20.8\).
Final Answer:
\[ \boxed{20.8} \]