Download AKTU B-Tech 6th Sem 2017-2018 NEE602 Switchgear And Protection Question Paper

Download AKTU (Dr. A.P.J. Abdul Kalam Technical University (AKTU), formerly Uttar Pradesh Technical University (UPTU) B-Tech 6th Semester (Sixth Semester) 2017-2018 NEE602 Switchgear And Protection Question Paper

Printed Paes: 02 Sub Code: NEE602
Paperld: IJIIDEIDIJ RollNo.| | | | | | | | | | |
B.TECH.
(SEM VI) THEORY EXAMINATION 2017-18
SWITCHGEAR AND PROTECTION
T ime: 3 Hours T otal Marks: 100
Note: Attempt all Sections. If require any missing data; then choose suitably.
SECTION A
1. Attempt all questions in brief. 2 x10 = 20
Explain what you understand by pick-up value of actuating quantity.
Discuss what you understand by stability of a protective relay.
Explain time setting of over-current relay.
Compare the time-current characteristics of very inverse relay with that of IDMT relay.
Explain brie?y reactance relay characteristic on the R-X diagram
What do you understand by the term ?under-reach??
What type of protective device is used for the protection of an alternator against overheating
of its rotor?
What is magnetizing inrush current?
Discuss the energy balance theory of arc interruption in circuit breaker.
De?ne breaking capacity of a circuit breaker.
He: ?10 we 9.0 cs?
SECTION B
2. Attempt any three of the following: 10 x 3 = 30
a. Discuss the working principle, types and applications of thermal relays.
b. Explain stepped time?distance characteristics of three impedance relaying
units used for I, II and III zone of protection.
c. What is carrier current protection? What are its merits and demerits?
d. Discuss the protection employed for the field winding of the alternator
against ground faults.
e. Discuss the operating principle of vacuum circuit breaker. What are its
advantages over other circuit breakers?
SECTION C
3. Attempt any one part of the following: 10 x 1 = 10
a. What are the various types of over?current relays? Discuss their area of
applications.
b. Explain what you understand by primary and back-up protection. What
are the various methods of providing back?up protection?
4. Attempt any one part of the following: 10 x 1 = 10
a. What are the different types of attracted armature type relays? Explain why
they are noisy.
b. What are the different types of amplitude comparators? Discuss the operating
principle of rectifier bridge amplitude comparator.
5. Attempt any one part of the following: 10 x 1 = 10
a. Draw and explain the characteristic of MHO relay on R?X diagram. Discuss the effect
of power surge on its performance.

b. What is unit protection? Discuss the phase comparison scheme of carrier current
protection.
Attempt any one part of the following: 10 x 1 = 10
a. What are the different methods of testing of circuit breakers? Discuss
their merits and demerits.
b. Explain the terms: re?striking voltage, recovery voltage and RRRV.
Derive expression for re?striking voltage and RRRV in terms of system
voltage, inductance and capacitance.
Attempt any one part of the following: 10 x 1 = 10
a. Discuss the protection employed against loss of excitation of the alternator.
b. With a neat sketch, discuss the differential scheme for bus?zone protection.