400 Important Transformer MCQ Question and Answer | PDF Free Download
1.Grain oriented laminated sheet steel in transformer reduces
- ACopper loss
- BEddy current loss
- CHysteresis loss
- DNone of the above
2.Silicon content in iron laminations is kept within 5% as it
- AIncreases hysteresis loss
- BIncreases cost
- CMakes the material brittle
- DReduces the curie point
3.The permissible flux density in cold rolled grain-oriented steel is about
- A1.8T
- B2.5T
- C3.5T
- D4.5T
4.If the iron core of a transformer is replaced by an air core, then the hysteresis losses in the transformer will
- AIncrease
- BDecrease
- CRemain unchanged
- DBecome zero
5.Which of the following will improve the mutual coupling between primary and secondary circuits?
- ATransformed oil of high breakdown voltage
- BHigh reluctance magnetic core
- CWinding material of high resistivity
- DLow reluctance magnetic core.
6.In order to reduce the hysteresis loss
- ACore may be laminated
- BSilicon steel may be used as the core material
- CCore may be constructed with any permanent magnet material such as Alnico
- DCore may be impregnated with varnish
7.Why is the core of the transformer built up of laminations?
- ATo reduce eddy current loss
- BFor convenience of fabrication
- CNo specific advantage
- DFor increasing the permeability
8.When are eddy current losses in a transformer reduced?
- AIf laminations are thick
- BIf the number of turns in primary winding is reduced
- CIf the number of turns in secondary winding is reduced
- DIf laminations are thin.
9.Transformer core laminations are coated with an enamel layer in order to
- AReduce hum
- BAttain adhesion between laminations
- CInsulate laminations from each other
- DPrevent corrosion of the lamination
10.The yoke sections of transformers employing hot rolled laminations is made 15 percentage more than that of core in order to
- AReduce the copper losses
- BReduce the magnetizing current and iron loss in yoke
- CProvide better cooling
- DAll of the above
11.The joints in the transformer core lamination are staggered so as to
- AAvoid continuous gap causing increase in magnetizing current
- BIncrease the mechanical strength of the assembled core
- CAvoid under humming noise
- DAll of the above
12.The degree of mechanical vibration caused by core lamination in a transformer depends on
- ASize of laminations
- BGauge of laminations
- CTightness of clamping
- DAll of the above
13.The noise, in a transformer, caused by vibrations of laminations set by magnetic forces, is termed as
- AZoom
- BHum
- CBuzz
- DNone of these
14.The primary and secondary windings are interlaced for
- AEasiness of coil making
- BReduced leakage reactance
- CReduced cost
- DUniform heating
15.The leakage flux of primary and secondary windings in a transformer can be reduced to the minimum by
- AWinding primary and secondary coils on separate limbs.
- BWinding primary and secondary coils one upon the other coaxially
- CIncreasing the number of turns
- DEmploying low permeability magnetic material core
16.The concentric windings are used in core type transformers with _____winding placed next to the core
- ALV
- BPrimary
- CHV
- DSecondary
17.Low voltage windings are placed next to the core in the case of concentric windings as in this case _____is/are reduced
- Ahysteresis loss
- Bleakage fluxes
- Ceddy current loss
- Dinsulation requirement
18.In a power transformer
- APrimary winding is always wound with many turns of thin wire.
- BSecondary winding is always wound with lesser number of turns of thin wire
- CLow voltage winding is always wound with lesser number of turns of thicker wire
- DHigh voltage winding is always wound with larger number of turns of thicker wire
19.In transformers, the primary and secondary are interlaced so that
- AThere may be maximum flux linkage between the two windings
- BCopper is saved
- CBoth (a) and (b)
- DStatements is false
20.In a large capacity transformer, 5% of the turns at the end of hv winding are provided with extra insulation so as to provide protection
- AAgainst corona
- BAgainst lightening
- CDue to surges occurring during switching operations
- DAll of the above