UNIT – IV
ALERNATOR AND
TRANSMISSION LINE PROTECTION
PART – A (2
MARKS)
1. What are the types of stator
winding faults in alternator?
2. Mention the most commonly used
protection scheme for alternators.
3. What are the types of feeders
in power system.
4. What is meant by radial
feeder?
5. What is the disadvantage of
radial feeder?
6. What are the relays used for
time graded protection in radial feeders.
PART - B
1. Enumerate the relaying schemes
which are employed for the protection of a modern alternator. (16)
2. (a) What is transverse or
split phase protection of an alternator? (4)
(b) What type of fault is this scheme
of protection employed? (4)
(c) With a neat sketch discuss
the working principle of this scheme. (8)
3. What type of a protective
device is used for the protection of an alternator against overheating of its
(i) stator (ii) rotor? Discuss them in brief. (8+8)
4. What type of a protective
scheme is employed for the protection of the field winding of the alternator
against ground faults? (16)
5. Discuss the protection
employed against loss of excitation of an alternator. (16)
6. (a) What do you understand by
field suppression of an alternator? (8)
(b) How is it achieved? (8)
7. Briefly discuss the protection
of an alternator against.
(i) Vibration of distortion of
motor (4)
(ii) Bearing overheating (4)
(iii) Auxiliary failure (4)
(iv) Voltage regulator failure
(4)
8. What type of pilot protection
is used for EHV and UHV transmission lines. (16)
9. (a) What is carrier
protection? (4)
(b) For what voltage range is it
used for the protection of transmission line? (4)
(c) What are its merits and
demerits? (8)
10. (a) What is carrier aided
distance protection. (4)
(b) What are its different types?
(4)
(c) Discuss the permissive
under-reach transfer tripping scheme of protection. (8)
11. (a) Draw and explain the
merz-price protection of alternator stator winding. (10)
(b) A generator is protected by
restricted earth fault protection. The generator ratings are 13.2kv, 10MVA. The
percentage of winding protected against phase to ground fault is 85%. The relay
setting is such that it trips for 20% out of balance calculate the resistance
to be added in the neutral to ground connection. (6)