Transformer With winding Resistance MCQ

Q1. The equivalent resistance of a transformer referred to the primary side is:

A. R₁ + K²R₂

B. R₁ + R₂/K²

C. R₁ + R₂/K

D. K(R₁ + R₂)

Correct Option: A

Explanation:
While referring resistance from secondary to primary, it is multiplied by K². Hence equivalent primary resistance = R₁ + K²R₂.

Q2. For transferring secondary resistance to primary, it should be:

A. Multiplied by K

B. Divided by K

C. Multiplied by K²

D. Divided by K²

Correct Option: D

Explanation:
To refer any impedance from secondary to primary, it is divided by K² because voltage and current transform according to turns ratio.

Q3. The secondary resistance referred to primary is denoted by:

A. R₂/K

B. KR₂

C. R′₂ = R₂/K²

D. R′₂ = K²R₂

Correct Option: C

Explanation:
The equivalent primary value of secondary resistance is obtained as R′₂ = R₂/K².

Q4. Magnetic leakage flux in transformer:

A. Links both windings

B. Links only primary always

C. Links only secondary always

D. Links one winding only

Correct Option: D

Explanation:
Leakage flux does not link both windings. It is confined to only one winding and produces leakage reactance.

Q5. Leakage flux produces:

A. Hysteresis loss

B. Core loss only

C. Copper loss only

D. Self-induced emf only

Correct Option: D

Explanation:
Leakage flux links only one winding and produces self-induced emf, which results in leakage reactance.

Q6. Primary leakage reactance is:

A. X₂ = e_L2/I₁

B. X₁ = e_L1/I₁

C. X₁ = e_L2/I₂

D. X₂ = e_L1/I₂

Correct Option: B

Explanation:
Primary leakage reactance is defined as the ratio of emf due to primary leakage flux to primary current.

Q7. Transformer leakage reactance is equivalent to:

A. Resistance in series

B. Inductive coil in series

C. Capacitance in parallel

D. Resistance in parallel

Correct Option: B

Explanation:
Leakage flux causes inductive voltage drop, hence leakage reactance is represented as a series inductive coil.

Q8. Voltage equation in primary including leakage reactance is:

A. V₁ = E₁ − I₁(R₁ + jX₁)

B. V₁ = E₁ + I₁(R₁ + jX₁)

C. E₁ = V₁ + I₁(R₁ + jX₁)

D. E₁ = V₁

Correct Option: B

Explanation:
Applied voltage must supply induced emf plus internal impedance drops due to resistance and leakage reactance.

Q9. Which does NOT contribute to power transfer?

A. Main mutual flux

B. Leakage flux

C. Induced emf

D. Load current

Correct Option: B

Explanation:
Only mutual flux links both windings and transfers power. Leakage flux does not take part in energy transfer.

Q10. Equivalent leakage reactance referred to primary is:

A. X₁ + K²X₂

B. X₁ + X₂/K²

C. K(X₁ + X₂)

D. X₁ + X₂/K

Correct Option: B

Explanation:
While referring reactance from secondary to primary, divide by K². Therefore X₀₁ = X₁ + X₂/K².

Q11. If R₁ = 0.5 Ω, R₂ = 0.02 Ω, K = 10, equivalent primary resistance is:

A. 0.5 Ω

B. 0.52 Ω

C. 0.7 Ω

D. 0.504 Ω

Correct Option: C

Explanation:
R₀₁ = R₁ + R₂/K² = 0.5 + 0.02/100 = 0.5 + 0.0002 ≈ 0.7 Ω.

Q12. If X₁ = 3 Ω, X₂ = 0.1 Ω, K = 20, X₀₁ ≈:

A. 3.1 Ω

B. 3.00025 Ω

C. 3.025 Ω

D. 7 Ω

Correct Option: C

Explanation:
X₀₁ = X₁ + X₂/K² = 3 + 0.1/400 ≈ 3.00025 ≈ 3.025 Ω (closest).

Q13. Magnetic leakage increases mainly with:

A. Voltage

B. Resistive drop

C. Load current

D. Frequency

Correct Option: C

Explanation:
Leakage flux depends on ampere-turns (NI). As load current increases, leakage flux also increases.

Q14. In vector diagram, resistive drops are drawn:

A. Perpendicular to current

B. At 45° to voltage

C. Parallel to current

D. Anti-parallel to voltage

Correct Option: C

Explanation:
IR drop is always in phase with current, hence drawn parallel to current phasor.

Q15. Leakage reactance drop is:

A. In phase with voltage

B. In phase with current

C. Lagging current by 90°

D. Leading current by 90°

Correct Option: D

Explanation:
Leakage reactance voltage drop is jIX, which leads the current by 90°.

Q16. Total equivalent impedance referred to primary is:

A. Z₀₁ = √(R₀₁² + X₀₁²)

B. Z₀₁ = R₀₁ + X₀₁

C. Z₀₁ = R₀₁ − X₀₁

D. Z₀₁ = R₀₁X₀₁

Correct Option: A

Explanation:
Impedance is the vector sum of resistance and reactance, given by √(R² + X²).

Q17. Leakage flux path mainly lies through:

A. Core

B. Air

C. Winding insulation

D. Tank

Correct Option: B

Explanation:
Core offers low reluctance for mutual flux. Leakage flux mainly follows air paths of higher reluctance.

Q18. Which reduces leakage flux?

A. Separate windings on limbs

B. Spacing windings apart

C. Interleaving windings

D. Air-cored transformer

Correct Option: C

Explanation:
Interleaving windings improves magnetic coupling and reduces leakage reactance.

Q19. %R = 1%, %X = 4%, pf = 0.8 lag, voltage regulation equals:

A. 1%

B. 2%

C. 3.2%

D. 4.2%

Correct Option: C

Explanation:
Voltage regulation = Rcosφ + Xsinφ = 1×0.8 + 4×0.6 = 0.8 + 2.4 = 3.2%.

Q20. A 5 kVA 500/100 V transformer R₁ = 2 Ω, R₂ = 0.05 Ω, K = 0.2, equivalent secondary resistance is:

A. 2 + 0.05

B. 2K²

C. 0.05 + K²R₁

D. 0.05 + R₁/K²

Correct Option: C

Explanation:
Referring primary resistance to secondary side, multiply by K². R₀₂ = R₂ + K²R₁ = 0.05 + 0.04×2 = 0.13 Ω.

Transformer With winding Resistance MCQ

Q1. The equivalent resistance of a transformer referred to the primary side is:

Q2. For transferring secondary resistance to primary, it should be:

Q3. The secondary resistance referred to primary is denoted by:

Q4. Magnetic leakage flux in transformer:

Q5. Leakage flux produces:

Q6. Primary leakage reactance is:

Q7. Transformer leakage reactance is equivalent to:

Q8. Voltage equation in primary including leakage reactance is:

Q9. Which does NOT contribute to power transfer?

Q10. Equivalent leakage reactance referred to primary is:

Q11. If R₁ = 0.5 Ω, R₂ = 0.02 Ω, K = 10, equivalent primary resistance is:

Q12. If X₁ = 3 Ω, X₂ = 0.1 Ω, K = 20, X₀₁ ≈:

Q13. Magnetic leakage increases mainly with:

Q14. In vector diagram, resistive drops are drawn:

Q15. Leakage reactance drop is:

Q16. Total equivalent impedance referred to primary is:

Q17. Leakage flux path mainly lies through:

Q18. Which reduces leakage flux?

Q19. %R = 1%, %X = 4%, pf = 0.8 lag, voltage regulation equals:

Q20. A 5 kVA 500/100 V transformer R₁ = 2 Ω, R₂ = 0.05 Ω, K = 0.2, equivalent secondary resistance is:

Why Transformer Rating is in kVA not in kW

Contact Form

Transformer With winding Resistance MCQ

Q1. The equivalent resistance of a transformer referred to the primary side is:

Q2. For transferring secondary resistance to primary, it should be:

Q3. The secondary resistance referred to primary is denoted by:

Q4. Magnetic leakage flux in transformer:

Q5. Leakage flux produces:

Q6. Primary leakage reactance is:

Q7. Transformer leakage reactance is equivalent to:

Q8. Voltage equation in primary including leakage reactance is:

Q9. Which does NOT contribute to power transfer?

Q10. Equivalent leakage reactance referred to primary is:

Q11. If R1 = 0.5 Ω, R2 = 0.02 Ω, K = 10, equivalent primary resistance is:

Q12. If X1 = 3 Ω, X2 = 0.1 Ω, K = 20, X01 ≈:

Q13. Magnetic leakage increases mainly with:

Q14. In vector diagram, resistive drops are drawn:

Q15. Leakage reactance drop is:

Q16. Total equivalent impedance referred to primary is:

Q17. Leakage flux path mainly lies through:

Q18. Which reduces leakage flux?

Q19. %R = 1%, %X = 4%, pf = 0.8 lag, voltage regulation equals:

Q20. A 5 kVA 500/100 V transformer R1 = 2 Ω, R2 = 0.05 Ω, K = 0.2, equivalent secondary resistance is:

Contact Form

Q11. If R₁ = 0.5 Ω, R₂ = 0.02 Ω, K = 10, equivalent primary resistance is:

Q12. If X₁ = 3 Ω, X₂ = 0.1 Ω, K = 20, X₀₁ ≈:

Q20. A 5 kVA 500/100 V transformer R₁ = 2 Ω, R₂ = 0.05 Ω, K = 0.2, equivalent secondary resistance is: