Objectives on Insulating materials and their properties, applications and limiting current
This sets of objective questions or MCQs more focuses on insulating materials and their properties, applications and limiting current in part 2....
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SET 1 of Insulating materials, Properties & applications and Limiting temperature mcqs
1. The insulating material for cables should ______ .
A. be acid proof
B. be non-inflammable
C. be non-hygroscopic
D. have all above properties
Answer D
Marks 1
2. On which of the following factors does the resistivity of a material depend?
A. Resistance of the conductor
B. Cross- sectional area of the conductor
C. Length of the conductor
D. All of the above
Answer D
Marks 1
3.Calculate the breakdown strength of leatheroid paper, having thickness of 0.16 mm and the breakdown voltage is 2.5 kV.
A. 15.625 kV /mm
B. 1.156 kV /mm
C. 155.1 kV /mm
D. 156.25 kV /mm
Answer A
Marks 1
4. The breakdown voltage of a cable depends on ______.
A. presence of moisture
B. working temperature
C. time of application of the voltage
D. all of the above
Answer A
Marks 1
5.The insulation resistance of the cable decreases with _______.
A. the increase in length of the insulation
B. the decrease in the length of the insulation
C. either (A) or (B)
D. none of the above
Answer A
Marks 1
6.The forbidden gap in an insulator is ______.
A. large
B. small
C. nil
D. any of the above
Answer A
Marks 1
7.Base material for black varnish is
A. linseed oil
B. cellulose acetate
C. asphalt
D. cellulose nitrate
Answer C
Marks 1
8.All of the following are the preferred properties of a dielectric gas, EXCEPT
A. high dielectric strength
B. hysiological inertness
C. low atomic number
D. good heat transfer
Answer C
Marks 1
9.Use of unimpregnated paper is very limited due to
A. thermal instability
B. reaction with oxygen
C. hygroscopicity
D. all of above
Answer D
Marks 1
10.2250C is limiting temperature of
A. Silk
B. ica
C. Teflon
D. Cloth
Answer C
Marks 1
SET 2 of Insulating materials, Properties & applications and Limiting temperature mcqs
11. 1050C is limiting temperature of
A. Impregnated paper
B. Mica
C. Teflon
D. Cloth
Answer A
Marks 1
12. Vulcanized fiber paper treated with-------------- is used for bushings, washers.
A. Zinc chloride
B. Sodium chloride
C. Aluminium oxide
D. Zinc oxide
Answer A
Marks 1
13. 900C is limiting temperature of
A. Silk
B. Mica
C. Teflon
D. Rubber
Answer D
Marks 1
14. 1300C is limiting temperature of
A. Inorganic materials
B. Teflon
C. Cloth
D. Silk
Answer A
Marks 1
15. 1800C is limiting temperature of
A. Cloth
B. Composite materials in mica
C. Silk
D. Teflon
Answer B
Marks 1
16. Class F insulation has limiting temperature of ------- oC
A. 105
B. 120
C. 130
D. 155
Answer D
Marks 1
17.Class B insulation can withstand temperature up to ----- oC.
A. 105
B. 90
C. 155
D. 130
Answer D
Marks 1
18. Mica :: Commutator segment separators , Asbestos :: ?
A. Motors , Generators
B. Manufacturing of panel boards
C. Pin insulators
D. Capacitors
Answer B
Marks 1
19. In power and distribution transformers, insulating material for different parts are as follows, Turn to turn :: paper, Bushings:: ?
A. Mica
B. Craft paper
C. Air
D. Porcelain
Answer D
Marks 1
20.In power and distribution transformers, insulating material for different parts are as follows, Bushings :: Porcelain, Layer to layer:: ?
A. craft paper
B. Mica
C. Porcelain
D. Resins
Answer A
Marks 1
SET 3 of Insulating materials, Properties & applications and Limiting temperature mcqs
21. In power and distribution transformers, insulating material for different parts are as follows,
Bushings :: Porcelain, Low voltage coil to ground:: ?
A. craft paper
B. mica
C. pressboard
D. resins
Answer C
Marks 1
22.In power and distribution transformers, insulating material for different parts are as follows,
Bushings :: Porcelain , cooling media :: ?
A. craft paper
B. air
C. mica
D. pressboard
Answer B
Marks 1
23.In power and distribution transformers, insulating material for different parts are as follows,
Bushings :: Porcelain , between two turns :: ?
A. mica
B. pressboard
C. glass tapes
D. water
Answer C
Marks 1
24. In power and distribution transformer, insulating material for different parts are as follows, cooling media :: air , Between H.V coil to L.V. Coil :: ?
A. pressboard
B. air
C. mica
D. craft paper
Answer A
Marks 1
25.Low permittivity ceramic is used for making
A. Insulators
B. Supports
C. Boards
D. Slot insulation
Answer A
Marks 1
26.Nitrogen :: cooling media in transformer , sulphur hexafluoride:: ?
A. Gas insulated substation
B. Capacitors
C. Rotating machines
D. Electronic equipments
Answer A
Marks 1
27. Following insulating materials are used for different parts of electrical machinesConductor :: class A insulation, slot liner :: ?
A. Mica
B. Paper
C. Cotton tapes
D. Asbestos
Answer C
Marks 1
28. In electrical machines, insulating materials used for different parts are as follows -
Slot liner :: Fiber glass , Conductor :: ?
A.Mica
B.Paper
C.Glass
D.Cotton covering
Answer D
Marks 1
29. Class Y :: 90oC , Class A :: ?
A.100 oC
B.105 oC
C.225 oC
D.95 oC
Answer B
Marks 1
30. Class Y :: 90 oC , Class E :: ?
A. 120 oC
B. 105 oC
C. 225 oC
D. 95 oC
Answer A
Marks 1
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