400 Important Transformer MCQ Question and Answer | PDF Free Download
1.When a transformer winding suffers a short circuit, the adjoining turns of the same winding experience
- AAn attractive force
- BA repulsive force
- CNo force
- DBoth a & b
2.Under short circuit condition, the windings of transformer having 5% impedance will experience a radial force
- A5 times of full load value
- B20 times of full load value
- C25 times of full load value
- D400 times of full load value
3.Major insulation in a transformer is the insulation between the
- ALV Winding and Core
- BLV winding and HV winding
- CTurns of the winding turns
- DBoth (a) and (b)
4.Minor insulation in a transformer is the insulation between the
- ALV and HV windings
- BTurns of the windings
- CLayers of the windings
- DBoth (b) and (c)
5.In a transformer an insulating material may fail due to
- AMoisture
- BDust
- CVoids in the winding
- DAny one or more of the above
6.The function of oil in a transformer is
- ATo provide insulation and cooling
- BTo provide protection against lightning
- CTo provide protection against short circuit
- DTo provide lubrication
7.The color of fresh dielectric oil used in transformers is
- ADark brown
- BPale yellow
- CPale pink
- DWhite grey
8.Transformer oil must be free from
- AMoisture
- BSludges
- CGases
- DSulphur
9.The core and windings of a transformer are put in a steel tank in order to
- AMake it suitable for outdoor operation
- BProvide protection against mechanical damages and provide additional cooling
- CImprove its appearance
- DAll the above
10.conservator (for transformer) is used
- Ato take up the expansion of oil due to temperature rise
- Bto act as an oil storage
- Cfor better cooling of transformer
- Dnone of the above
11.In a large power transformer, a conservator drum is provided above the completely oil filled transformer tank and connected to it by a short pipe. The conservator drum is linked to external air through a breather. What is the purpose of providing the conservator?
- ATo store reserve oil to make up oil losses due leakage
- BTo prevent explosion due to rise in oil pressure inside the tank during a fault
- CTo accommodate change in oil level during the load cycle of the transformer load
- DTo expert additional pressure by the conservator oil on the oil inside the main tank to prevent disintegration of oil at high temperature
12.Sludge formation in transformer oil is due to which one of the following?
- AIngress of dust particles and moisture in the oil
- BAppearance of small fragments of paper, varnish, cotton and other organic materials in the oil
- CChemical reaction of transformer oil with the insulating materials
- DOxidation of transformer oil
13.In a power transformer, the breather is provided in order to
- AFilter transformer oil
- BPrevent ingress of moisture with air
- CProvide oxygen to the cooling oil
- DProvide fresh air for increasing cooling effect
14.The chemical used in breather of a transformer should have quality of
- AAbsorbing moisture
- BJoining air
- CCleansing the transformer oil
- DNone of the above
15.Malfunctioning of the Buchholz relay may be caused due to
- AHeavy external short circuits
- BImproper breather action
- CDropping of oil level below the relay level during operation
- DExcessive overheating
16.Which of the following statements associated with Buchholz relay is not TRUE?
- AIt is a voltage sensitive device
- BIt is used only on oil cooled transformers
- CIt is usually not provided on transformers of ratings below 500kVA
- DIts operating time is of the order of 0.1 second
17.A Buchholz relay is used for
- AProtection of a transformer against all internal faults
- BProtection of a transformer against external faults
- CProtection of a transformer against both internal and external faults
- DProtection of induction motors
18.For system voltages exceeding 66 kV, condenser bushings are preferred over non ?condenser bushings because
- AThe axial stresses can be eliminated
- BThe radial stresses can be made independent of the radial thickness of the dielectric
- COptimum utilization of dielectric because of inform potential distribution results in reduction of radial and axial dimensions of the bushings
- DNone of the above
19.Which is the arrangement of windings in a core type single phase transformer?
- AHalf Iv inside and half hv outside on each core limb
- BLv on one core limb and hv on the other
- CSandwiched I v and hv discs on each core limb
- DHalf hv inside and half hv outside on each core limb
20.For core type power transformers, both primary and secondary windings have circular coil sections as it
- AReduces core material requirement and so also reduces the core loss
- BGives the strongest mechanical shape
- CIs easier to wind
- DReduces the copper requirement