Elective – III : Electrical Distribution System

**NJR/KS/18/4716**

**Time : Three Hours **

**Max. Marks : 80**

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**Notes : 1. All questions carry marks as indicated.**

**2. Solve Question 1 OR Questions No. 2.**

**3. Solve Question 3 OR Questions No. 4.**

**4. Solve Question 5 OR Questions No. 6.**

**5. Solve Question 7 OR Questions No. 8.**

**6. Solve Question 9 OR Questions No. 10.**

**7. Solve Question 11 OR Questions No. 12.**

**8. Assume suitable data whenever necessary.**

**9. Use of non programmable calculator is permitted.**

1. a) Discuss the following terms : **[08 M] **

i) Diversity Factor

ii) Coincidence Factor

iii) Utilization Factor

iv) Contribution Factor

b) Discuss in detail the classification of loads with their characteristics. **[05 M]
**

2. a) Derive the relation between load factor & loss factor. **[06 M] **

b) A generating station has a maximum demand of 80 MW and a connected load of 150 MW. If MWhr generated in a year are 400 x 10^{3}. Calculate : **[07 M]**

i) Load Factor

ii) Demand Factor

3. a) Draw a line diagram of a radial type primary feeder. Mention the factors that influence the selection of primary feeders. **[06 M]**

b) Explain the voltage choice & feeder design for secondary distribution system. **[07 M]
**

4. a) Explain the following : **[06 M]**

i) Radial type feeders with tie & sectionalising switches.

ii) Radial feeder with express feeder & back feed.

iii) Loop type primary feeder.

b) An industrial area near a city was found to have a load density of 0.5MVA / km^{2 }. The total area was to be located between a rectangular screen of 8km x 4km . Determine the suitable number of 33KV /11KV substation, their capacity & feeder length. The loads are to be served by 11 KV feeders. **[07 M] **

5. a) Derive the expression for power loss & voltage drop for the feeder line with uniformly decreasing load. **[07 M]**

b) A 400KV, 3Φ , 4 wire system has balanced loads and is fed from a 11KV / 400V, 3Φ 100KVA transformer. Determine voltage drop, output KVA, KW & pf. of a transformer. The impedances are : **[07 M] **

section oa =(0.06 + j0.04) Ω

section ab = (0.1 + j0.05) Ω

**OR**

6. a) What are the different distribution systems for ac & dc? Give comparison. **[07 M]**

b) For the distribution system shown below, the supply voltage is 240 V. Determine the power loss, KVA, KW & pf at the supply end. **[07 M]**

7. a) Briefly explain the line drop compensation & voltage control. **[06 M]
**

b) A 33 KV feeder has (0.1 + j0.25)Ω impedance per phase per km and is supplying a load of 6 MVA over a distance of 80 km at 0.75 pf. What will be the receiving end voltage and voltage drop of line if compensated to 50% by series capacitance compensation.

**OR**

8. a) Explain the location of shunt & series capacitors in pf correction. **[06 M]**

b) An industry has a total induction motor load at 100 hp, efficiency 0.88 and pf 0.8. It is necessary to correct pf to 0.9 lag. Determine the capacitor bank needed. **[07 M]**

9. a) What is SCADA? How does it help for distribution automation? **[07 M]**

b) Write a short note on substation automation. **[07 M]
**

10. a) What is earthing? How is it effectively done? What are the methods of reducing earth resistance? **. [07 M] **

b) Write short note on data acquisition system. **. [07 M] **

11. a) Explain the various factors to be considered to decide the ideal location of substation**. [06 M]
**

b) Discuss bus arrangement and switching systems in substations.

**OR**

12. a) What are the different types of faults that can occur on distribution network? Explain them with line diagram. **. [06 M] **

b) Give the arrangement of a single transformer 11KV / 415V substation & its layout. **. [07 M] **