UNIT – III
HRC FUSES AND
SWITCHES
PART – A (2
MARKS)
1. Define Fuse?
2. Define fuse element or (fuse
wire)
3. What are the materials
commonly used for fuse elements.
4. Define minimum fusing current?
What are the factors at which it depends?
5. How the minimum fusing current
does differs for stranded wires?
6. Define fusing factor?
7. What are the types of fuses?
8. What are main advantages of
HRC fuses?
9. What are the main
disadvantages of HRC fuses
10. Mention the points in
selection of fuse?
11. Define isolator and explain
its requirements.
12. Define earthing switch?
13. What is the necessacity of
earthing switch?
14. What are the types of
isolators?
15. What is main advantage of
pantograph isolator?
16. What is a gas insulated
substation.
PART - B
1. Describe the construction and
operation of the HRC cartridge fuse. What are itsadvantage and disadvantage?
(16)
2. Explain the following terms:
(i) Minimum fusing current (4)
(ii) Rated current (4)
(iii) Fusing factor (4)
(iv) Prospective current. (4)
3. What are the considerations in
selection a fuse for
(i) Transformer protection (3)
(ii) Motor protection (3)
(iii) Capacitor protection (3)
(iv) Heaters (3)
(v) Lighting loads (4)
4. Write short notes on
(i) Semi-enclosed rewirable fuse
(4)
(ii) D-type cartridge fuse (4)
(iii) Applications of HRC fuses
(4)
(iv) Drop-out fuse (4)
5. (a) What is a fuse? What are
its duties? Why lead in alloy fuse is the best for only low value of current?
(8)
(b) What are the factors on which
the current carrying capacity of the fuse depends? (8)
6. (a) What are the types of
isolators? Briefly explain the necessacity of earthing switch and its
applications. (8)
(b) Explain the working of
pantographic isolators? (8)
7. Explain the advantages of gas
insulator substation, probable location where it can be located and its
demerits. (16)
8. State the sequence of
operation of circuit breaker, isolator and earthing switch.
(i) while opening (8)
(ii) while closing (8)
No comments:
Post a Comment
Add your valuable comments Here . . .