01. Which of the following protects a cable against mechanical injury ?
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(a) Bedding
(b) Sheath
(c) Armouring
(d) None of the above
02. Which of the following insulation is used in cables ?
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(a) Varnished cambric
(b) Rubber
(c) Paper
(d) Any of the above
03. The thickness of the layer of insulation on the conductor, in cables, depends upon
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(a) reactive power
(b) power factor
(c) voltage
(d) current carrying capacity
04. The insulating material for cables should
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(a) be acid proof
(b) be non-inflammable
(c) be non-hygroscopic
(d) have all above properties
05. The current carrying capacity of cables in D.C. is more than that in A.C. mainly due to
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(a) absence of harmonics
(b) non-existence of any stability limit
(c) smaller dielectric loss
(d) absence of ripples
06. In case of three core flexible cable the colour of the neutral is
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(a) blue
(b) black
(c) brown
(d) none of the above
07. Conduit pipes are normally used to protect _____ cables.
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(a) unsheathed cables
(b) armoured
(c) PVC sheathed cables
(d) all of the above
08. The minimum dielectric stress in a cable is at
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(a) armour
(b) bedding
(c) conductor surface
(d) lead sheath
09. Dielectric strength of rubber is around
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(a) 5 kV/mm
(b) 15 kV/mm
(c) 30 kV/mm
(d) 200 kV/mm
10. The surge resistance of cable is
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(a) 5 ohms
(b) 20 ohms
(c) 50 ohms
(d) 100 ohms
11. PVC stands for
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(a) polyvinyl chloride
(b) post varnish conductor
(c) pressed and varnished cloth
(d) positive voltage conductor
12. In the cables, the location of fault is usually found out by comparing
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(a) the resistance of the conductor
(b) the inductance of conductors
(c) the capacitances of insulated conductors
(d) all above parameters
13. The material for armoring on cable is usually
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(a) steel tape
(b) galvanised steel wire
(c) any of the above
(d) none of the above
14. The relative permittivity of rubber is
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(a) between 2 and 3
(b) between 5 and 6
(c) between 8 and 10
(d) between 12 and 14
15. In cables the charging current
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(a) lags the voltage by 90°
(b) leads the voltage by 90°
(c) lags the voltage by 180°
(d) leads the voltage by 180°
16. In the cables, sheaths are used to
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(a) prevent the moisture from entering the cable
(b) provide enough strength
(e) provide proper insulation
(d) none of the above
17. In a cable the voltage stress is maximum at
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(a) sheath
(b) insulator
(c) surface of the conductor
(d) core of the conductor
18. The advantage of cables over overhead transmission lines is
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(a) easy maintenance
(b) low cost
(c) can be used in congested areas
(d) can be used in high voltage circuits
19. Which of the following distribution systems is more reliable ?
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(a) Radial system
(b) Tree system
(c) Ring main system
(d) All are equally reliable
20. Transmission voltage of 11 kV is normally used for distances upto
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(a) 20—25 km
(b) 40—50 km
(c) 60—70 km
(d) 80—100 km