ASSIGNMENT-2
Electrical Machines-I
Q1. The transformer works on the principle of _____.
Q2. Copper losses in transformer vary with______.
Q3. In a step-up transformer secondary voltage is_____ than primary.
Q4. Why is the core of transformer laminated?
Q5. What is the effect of unequal voltage ratios in parallel operated
transformers?
Q6. In parallel operation, why should transformers have the same
phase angle?
Q7. Define transformation ratio.
Q8. State the principle on which transformers operate.
Q9. Iron losses in a transformer depend primarily on______.
Q10. Mention one reason why transformer efficiency is high.
Q11. What is the effect of unequal voltage ratios in parallel operated
transformers?
Q12. In parallel operation, why should transformers have the same
phase angle? Explain the working of a transformer with the help of a
neat diagram. How does it step up or step-down voltage?
Q13. A transformer has 500 primary turns and 1500 secondary turns,
supplied with 220V. Compute the secondary voltage and primary
current if the load draws 3 A.
Q14. Derive the EMF equation of a transformer and explain the
significance of each term. Then calculate the EMF induced in the
primary winding of a transformer having 500 turns, operating at 50 Hz,
with a maximum flux of 0.02 Wb.
Q15. Draw and explain the phasor diagram of a single-phase
transformer on no-load condition.
Q16. List and explain the different types of losses in a transformer. How
do these losses affect the efficiency of a transformer?
Q17. A transformer has an output power of 200kW. The core losses are
3 kW, and the copper losses at full load are 4 kW. Calculate the
efficiency of the transformer. What factors can be improved in the
design of the transformer to increase its efficiency? Discuss.
Q18. Explain the conditions required for the parallel operation of
single-phase transformers. Why are these conditions important?
Q19. A 230 V to 115 V autotransformer supplies 8 kW. Find the power
shared by conduction and induction. Justify its efficiency.
Q20. List and explain the main parts of a transformer and their
functions.
Q21. Explain the procedure of the open circuit test on a single-phase
transformer. What parameters are obtained from this test, and how are
they used?
Q22. Illustrate and explain the phasor diagram of a transformer under
load.
Q23. List types of transformer losses. How do each type affect
performance?
Q24. A transformer has output power of 100 kW, iron losses of 2 kW
and copper losses of 3 kW. Find efficiency. What design changes
improve this?
Q25. What are the necessary conditions for parallel operation of single-
phase transformers?
