SUBJECT CODE: BELED-101

Paper II: [110004]

- Section A is Compulsory.
- Attemp any four questions for Section B.
- Attemp any two questions for Section C.
- Any missing data may be assumed appropriately

Q1

- From fundamentals obtain expressions for power energy?
- Define RMS value, average value and form factor
- Indicate how the parameters in a series RLC circuit vary with frequency
- Discuss the advantages of 5-phase sytem over single phase system
- What are the different types of Induction motors?
- State Lenz's law
- What is form factor
- Explain armature reaction in D.C. machine
- State and explain krichhhoff's laws.
- Plot and waveform of voltage and current for R-L series circuits

Q2. Write the relationship of star-delta transformation of three resistors.

Q3. Explain frequency,time period,Instentaneous value, maximum value and average value for a sinusoidal voltage

Q4. A single-phase transformer is required to step down and voltage from 1100 V to 400 V at 50 Hz The core has a cross-sectional area of 25 cm^{2} and the maximum flux density is 5 Wb/m^{2}. Determine the number of turns of the primary and secondary windings.

Q5. Three identical coins are connercted in star across a three-phase 415 V, 50 Hz supply. The total power drawn is 3 kW at a rower factor of 0.3. Calculate the resistance and indusctance of each coil.

Q6. Explain the principal of working of three-phase induction motor.

Q7. What do you understand by D.C. machines? What are the different types of D.C. machines? Discuss working principle of these machines. Explain the function of brush and commutator in a dc machine for generating action

Q8. Write short notes on the following: (i) Magnetzing reactance (ii) Leakage reactance (iii) Efficiency

Q9. Explain 3-phase EMF generation Derive relationship between phase and line for three phase star connections and delta connections.