Code No.

A24A5 R15
BVRAJU INSTITUTE OF TECHNOLOGY, NARSAPUR
(UGC-AUTONOMOUS)
B.Tech II Year II Semester Supplementary Examinations, July 2021
POWER SYSTEMS-I
(Electrical and Electronics Engineering)
Time: 3 Hours Max.Marks:70
Note: This Question Paper Contains two Parts A and B
Part A is Compulsory which carries 20 marks. Answer all questions in Part A at one place only.
Part B Consists of 10 questions. Answer any five (one full question from each unit). Each
question carries 10 marks and may have a, b, c as sub questions
PART-A ( 10 X 2 = 20 Marks)
1. a) Explain the function of Super Heater in thermal power plants 2 M [CO1 BL2]
b) Explain the function of Moderator in Nuclear Power Plants 2 M [CO1 BL2]
c) Draw the Block diagram which represents the gas power station 2 M [CO2 BL1]
d) Differentiate U.G Cable and O.H line 2 M [CO2 BL3]
e) List the various bus-bar arrangements in the sub-stations 2 M [CO3 BL1]
f) List the advantages of Gas Insulated Sub-stations 2 M [CO3 BL1]
g) List the methods of voltage control 2 M [CO4 BL1]
h) Explain the function of Booster Transformers 2 M [CO4 BL2]
i) Define Load Factor 2 M [CO5 BL1]
j) What is the tariff ? 2 M [CO5 BL1]
PART-B
2 a) Draw Block Diagram of Thermal Power Station and explain the individual elements
7 M [CO1 BL2]
b) Explain the function of cooling towers in thermal power stations with neat diagram
3 M [CO1 BL2]
OR
3 a) Draw Block Diagram of Nuclear Power Station and explain the individual elements
7 M [CO1 BL2]
b) Explain the principle and operation of gas power station 3 M [CO1 BL2]
***
4 a) Explain what are the advantages and dis-advantages of DC over AC systems.
5 M [CO2 BL2]
b) A single phase distributor has a total resistance of 0.2 Ohm and a reactance of 0.3 Ohm, at the
mid point(A) a current of 100A at 0.6 P.F lagging at the far end (B) a current of 100 A at 0.8 P.F
Lagging is tapped. If the voltage at the far end is 200Volts find the voltage at the supply end and
also its phase angle w.r.t voltage at far end . when i) the P.F ‘ s are w.r.t respective voltages at
the load points ii) the P.F’s are w.r.t voltages at the far end . 5 M [CO1 BL3]
OR
5 a) An Electric Train taking a constant current of 600 Amps moves on a section of line between
two sub-stations 8 Km apart and maintained at 575 and 590 volts respectively. The track
resistance is 0.04 Ohm per Km both go and return. Find the point of minimum potential along
the track and currents supplied by two sub-stations at that instant. 5 M [CO2 BL3]

b) Explain what are the design requirements of Distributions systems 5M [CO2 BL2]
***
6 a) Explain the principle and operation of Gas Insulated Sub-Station along with Single Line
Diagram 5 M [CO3 BL2]
b) Explain the various components present in sub-station with neat lay out?
5 M [CO3 BL2]
OR
7 a) what are the various types of bus-bar arrangements in the sub-stations and explain with neat
diagram ? 6 M [CO3 BL2]
b) Discuss about the different types of sub-stations? 4 M [CO3 BL2]
***
8 a) Explain the methods of improving of P.F in details 6 M [CO4 BL2]
b) Explain the principle and operation of Booster Transformer 4 M [CO4 BL2]
OR
9 a) Derive the equation for most economical power factor 6 M [CO4 BL2]
b) Explain the function of Synchronous capacitors 4M [CO4 BL2]
***
10 a) A Generating station supplied the following loads: 150 MW,120MW,85 MW,60MW and 5
MW. The station has a maximum demand of 220 MW. The Annual Load factor of the station is
48 percent. Calculate i) the Number of units supplied annually ii) the diversity factor iii) the
demand factor 6M [CO5 BL3]
b) Explain what are desirable characteristics of tariff 4 M [CO5 BL2]
OR
11 a) Explain how the cost of generation calculated 5M [CO5 BL2]
b) A Consumer has an annual consumption of 70,080 KWh . The charge is Rs.100 per KW of
Maximum Demand plus 5 paise per KWh . i) find the annual bill and the overall costs per KWh
if the load factor is 40 % ii) what is the overall cost per KWh if the consumption reduced by 25
% with the same load factor 5M [CO5 BL3]
***