400 Important Transformer MCQ Question and Answer | PDF Free Download
1.A shell type transformer is commonly used as it has
- ATwo magnetic paths
- BReduced magnetic flux leakage
- CReduce copper losses
- DBoth a and b
2.Spiral core transformer, in which core is made up of steel strip has the advantages of
- AMinimum losses
- BLighter construction
- CLesser weight
- DAll of the these
3.Distribution transformers are designed to have maximum efficiency nearly at ______ of full load
- A100%
- B70%
- C25%
- D10%
4.A distribution transformer is selected on the basis of
- AVoltage regulation
- BEfficiency
- CAll day efficiency
- DNone of those
5.The distribution transformers are designed with minimum possible iron losses. This is because
- AThe primary of a distribution transformer is energized for all the 24 hours
- BIron losses will cause undue heating
- CThe iron losses may cause damage to the insulation
- DNone of the above
6.Which part of transformer is subjected to maximum heating?
- AFrame
- BCore
- CWinding
- DOil
7.Which of the following methods is employed for cooling of power transformers of rating not exceeding 10 MVA?
- AAir blast cooling
- BNatural oil cooling
- CForced oil cooling
- DNatural air cooling
8.Natural air cooling is used for transformer of rating up to
- A100 kVA
- B500 kVA
- C5-10 kVA
- D10MVA
9.Additional of tubes to the transformer tank improves heat dissipation capacity because of
- AAdditional cooling surface
- BAdditional dissipation by radiation only
- CAdditional dissipation by convection only
- DAdditional dissipation by radiation and convection both
10.Which type of winding is used in 3-phase shell-type transformer?
- ACircular
- BCylindrical
- CSandwich
- DRectangular
11.The low voltage winding of a core type transformer is subdivided into two equal halves, each of half the original width of the single winding with the high voltage winding in between (instead of having the usual construction of low voltage winding adjacent to the core and surrounded by the high voltage winding). Such an interlacing of coils would make the combined primary and interlacing of coils would make the combined primary and secondary leakage reactance (in terms of the primary) nearly
- ATwice
- BEqual
- CHalf
- DOne fourth
12.Transformers are rated in kVA instead of kW because
- ALoad pf is often now known
- BkVA is fixed where kW depends on load pf
- Ctotal transformer loss depends on volt amperes
- Dit has become customary
13.five limb construction is preferred over three limb construction as in this type of construction
- Ahysteresis loss is reduced
- Beddy current loss is reduced
- Cmagnetic reluctance of the three phases can be balanced
- Dcopper losses are reduced
14.Which three phase connection can be used in a transformer to introduce a phase difference of 30 between its between its output and corresponding input line voltages?
- AStar -star
- BStar -delta
- CDelta- Delta
- DDelta- Zigzag
15.Which of the following connection of transformer will give the highest secondary voltage?
- ADelta primary, delta secondary
- BDelta primary, star secondary
- CStar primary, star secondary
- DStar primary, delta secondary
16.Which of the following 3-phase connections of a transformer causes interference to the nearby communication systems?
- ADelta star
- BStar delta
- CStar-star
- DDelta-delta
17.Scott connections are used for
- ASingle phase to three phase conversion
- BThree phases to single phase conversion
- CThree phases to two phase conversion
- DAny of the above
18.In Scott connections, the teaser transformer operates on 0.866 of its rated
- AImpedance
- BCurrent
- CVoltage
- DPower
19.In a transformer fed from a fundamental frequency voltage source, the source of harmonics is the
- AOverload
- BPoor insulation
- CIron loss
- DSaturation of core
20.Zero sequence current scan flow from a line into a transformer bank if the windings are
- AGrounded star / delta
- BDelta / star
- CStar / grounded star
- DDelta / delta