Electrical Studys

1] The chemical used in breather for transformer should have the quality of _____

1 pointA. ionizing airB. absorbing moistureC. cleansing the transformer oilD. cooling the transformer oil.

2] The chemical used in breather is ______

1 pointA. asbestos fibre B. silica sandC. sodium chlorideD. silica gel

3] An ideal transformer has infinite values of primary and secondary inductances. The statement is ____

1 pointA. TrueB. FalseC. No oneD. None of the above

4] The transformer ratings are usually expressed in terms of ____

1 pointA. volts B. amperesC. kWD. kVA

5] The noise resulting from vibrations of laminations set by magnetic forces, is termed as _____

1 pointA. magnetostrication B. booC. humD. zoom

6] Hysteresis loss in a transformer varies as CBmax = maximum flux density)

1 pointA. BmaxB. Bmax1-6C. Bmax1-83D. B max

7] Material used for construction of transformer core is usually _____

1 pointA. wood B. copperC. aluminiumD. silicon steel

8] The thickness of laminations used in a transformer is usually _____

1 pointA. 0.4 mm to 0.5 mm B. 4 mm to 5 mm C. 14 mm to 15 mmD. 25 mm to 40 mm

9] The function of conservator in a transformer is _____

1 pointA. to project against'internal faultB. to reduce copper as well as core lossesC. to cool the transformer oilD. to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings

10] The highest voltage for transmitting electrical power in India is _____

1 pointA. 33 kVB. 66 kVC. 132 kVD. 400 kV

11] In a transformer the resistance between its primary and secondary is ____

1 pointA. zero B. 1 ohmC. 1000 ohmsD. infinite

12] A transformer oil must be free from ___

1 pointA. sludge B. odourC. gasesD. moisture

13] A Buchholz relay can be installed on ____

1 pointA. auto-transformers B. air-cooled transformersC. welding transformersD. oil cooled transformers

14] Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds

1 pointA. 50°C B. 150°CC. 100°CD. 80°C

15] The main reason for generation of harmonics in a transformer could be

1 pointA. saturation of coreB. fluctuating loadC. poor insulationD. mechanical vibrations

16] Distribution transformers are generally designed for maximum efficiency around _____

1 pointA. 50% loadB. 90% loadC. zero loadD. 25% load

17] Which of the following property is not necessarily desirable in the material for transformer core ?

1 pointA. Mechanical strength B. Low hysteresis lossC. High thermal conductivityD. High permeability

18] Star/star transformers work satisfactorily when ..........

1 pointA. load is unbalanced only B. load is balanced onlyC. on balanced as well as unbalanced loadsD. none of the above

19] Delta/star transformer works satisfactorily when ........

1 pointA. load is balanced only B. load is unbalanced only C. on balanced as well as unbalanced loadsD. none of the above

20] Buchholz's relay gives warning and protection against ........

1 pointA. electrical fault inside the transformer itselfB. electrical fault outside the transformer in outgoing feederC. for both outside and inside faultsD. none of the above

You Got