Registration No:
-- 1
Total Number of Pages: 02
02 3 Course: B.Tech
Sub_Code: REL7D002
2 / 2
th
6 1
7 Semester/Regular/Back Examination: 2023-24
9 - 2 BRANCH(S): Electrical
SUBJECT: High Voltage Systems and DC Transmission
10 Time: 3 Hour
Max Marks: 100
Q.Code : N150
- - 1
Answer Question No.1 (Part-1) which is compulsory, any eight from Part-II and any two
2 0 23
from Part-III.
The figures in the right hand margin indicate marks.
12 /
2 6 / Part-I
Q1
a)
10 9-
Answer the following questions:
Mention what is Electrical breakdown?
1
(2 x 10)
b) Mention two circuits used to generate High Voltage DC.
3 --
c)
02
What is breakeven distance? Mention the range of breakeven voltage in overhead
2
transmission line.
2/
d)
2 6 /1
What is the use of smoothing reactor in HVDC transmission system?
e)
-
Name the instrument by which lighting surges can be recorded.
f)
g) 109
Mention the parameters on which the dimension of the voltage divider depends.
Mention the types of high voltage testing required by the electrical equipment.
h) What is Homopolar link, draw the schematics.
i)
-- 1
What are the criteria for selecting the valve rating used in the converter circuit for
HVDC system?
02 3
j)
1 2 /2
Compare the economics of DC cables with AC cables.
26 / Part-II
-
9 Answer Type Questions- (Answer Any Eight 1out of
Twelve) 10
Q2 Only Focused-Short (6 × 8)
3 - -
- 1 the characteristics of switching surges with necessary
a) Explain the special features of converter transformers.
b) Explain in -detail 0 2
2 twowaveforms.
0 2 3 2 /
c) What
2 are
/in details?
the different types of converter faults and
1
explain
6 / at least of the faults
/ 1 2
d) Explain briefly about various tests to be carried9 - 2
out on a bushing.
6 0
109-2 f) Explain the types of HVDC links and its purpose
e) Tabulate and explain the methods used for1 with neat diagram.
the measurement of high voltages.
g) Write short notes on Mixed R-C voltage dividers.
h) Explain with neat diagram the principle of operation, application and limitations of
Van de Graf generator.
i) Write short notes on Constant Alpha control.
j) Draw the schematic diagram of a typical HVDC converter station with 2 six pulse
-- 1
converter units and explain the function of each component.
Derive the Townsend’s current growth equation in uniform gaseous dielectric field.
k)
l)
02 3
Explain the Principles of Link Control in a VSC HVDC system.
2/ 2
2 6 /1
9 - Part-III
10 Type Questions (Answer Any Two out of Four)
Only Long Answer
Q3 Explain with neat sketch, the method of determining primary and secondary (16)
ionization coefficients with experimental setup.
- - 1
Q4 a)
0 23
A 6-pulse bridge connected inverter is fed from 238/110 kV transformer which is
connected with 3-ɸ, 238 kV, 50Hz supply. Calculate the direct voltage output when
2
(8x2)
/
the commutation angle is 200 and delay angle α is i) 300, ii) 900 and iii) 1500.
12
2 6 /
Comment on the results.
What do you understand from the term reactive power? Explain the causes of
9-
b)
reactive power absorbed by HVDC converter substation.
1 0 - 1 of 6-pulse
Q5 Explain with the help of neat diagram and wave forms, the 3 - operation (16)
bridge converter with delay angle α and overlap angle0 u2and derive the expression
for its dc output voltage.
2 / 2
6 /1
Q6
-
voltage of the supply transformer is9100
2kV at a frequency of 150 Hz. If the load
A ten stage Cockraft-Walton circuit has all capacitors of 0.06 µF. The secondary (16)
10 regulation (ii) the ripple voltage
current is 1 mA, determine (i) voltage
-- 1
02 3
2 / 2
6 / 1
9 - 2
10 3 -- 1
- - 1 2 0 2
0 2 3 2 /
/ 2 6 / 1
/ 1 2 9 - 2
- 2 6 1 0
109
