Transformers Mcqs – (Electrical Engineering) MCQs Latest For FPSC, PPSC, NTS, KPPSC, SPSC & Other Tests
“ Transformers Mcqs “. Tab this page to check “Latest Transformers MCQs” for the preparation of competitive mcqs, FPSC mcqs, PPSC mcqs, SPSC mcqs, KPPSC mcqs, AJKPSC mcqs, BPSC mcqs, NTS mcqs, PTS mcqs, OTS mcqs, Atomic Energy mcqs, Pak Army mcqs, Pak Navy mcqs, CTS mcqs, ETEA mcqs and others. The most occurred mcqs of Transformers in past papers. Past papers of Transformers mcqs. Past papers of Transformers MCQs. Transformers Mcqs are the necessary part of any competitive / job related exams. The Transformers mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Transformers mcqs. The Important series of Transformers Mcqs are given below:
Delta/star transformer works satisfactorily when______________?
A. load is unbalanced only
B. load is balanced only
C. on balanced as well as unbalanced loads
D. none of the above
Star/star transformers work satisfactorily when________________?
A. on balanced as well as unbalanced loads
B. load is balanced only
C. load is unbalanced only
D. none of the above
Which of the following property is not necessarily desirable in the material for transformer core ?
A. Low hysteresis loss
B. Mechanical strength
C. High thermal conductivity
D. High permeability
Distribution transformers are generally designed for maximum efficiency around________________?
A. zero load
B. 90% load
C. 25% load
D. 50% load
The value of flux involved m the e.m.f. equation of a transformer is____________?
A. r.m.s. value
B. average value
C. maximum value
D. instantaneous value
The main reason for generation of harmonics in a transformer could be_______________?
A. poor insulation
B. fluctuating load
C. mechanical vibrations
D. saturation of core
Gas is usually not liberated due to dissociation of transformer oil unless the oil temperature exceeds?
A. 80°C
B. 50°C
C. 100°C
D. 150°C
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be___________?
A. 1600 W
B. 6400 W
C. 800 W
D. 400 W
A Buchholz relay can be installed on______________?
A. air-cooled transformers
B. auto-transformers
C. welding transformers
D. oil cooled transformers
A transformer oil must be free from________________?
A. odour
B. sludge
C. gases
D. moisture
The core used in high frequency transformer is usually___________?
A. cost iron core
B. copper core
C. air core
D. mild steel core
In a transformer the resistance between its primary and secondary is____________?
A. 1 ohm
B. zero
C. 1000 ohms
D. infinite
Harmonics in transformer result in___________?
A. increased I2R losses
B. increased core losses
C. magnetic interference with communication circuits
D. all of the above
Helical coils can be used on___________?
A. low voltage side of high kVA transformers
B. high voltage side of small capacity transformers
C. high frequency transformers
D. high voltage side of high kVA rating transformers
The function of conservator in a transformer is___________________?
A. to reduce copper as well as core losses
B. to project against’internal fault
C. to cool the transformer oil
D. to take care of the expansion and contraction of transformer oil due to variation of temperature of sur-roundings
The thickness of laminations used in a transformer is usually____________?
A. 0.4 mm to 0.5 mm
B. 14 mm to 15 mm
C. 4 mm to 5 mm
D. 25 mm to 40 mm
Material used for construction of transformer core is usually___________________?
A. wood
B. aluminium
C. copper
D. silicon steel
Hysteresis loss in a transformer varies as CBmax = maximum flux density) ?
A. Bmax1-83
B. Bmax1-6
C. Bmax
D. B max
The noise resulting from vibrations of laminations set by magnetic forces, is termed as_________________?
A. boo
B. magnetostrication
C. hum
D. zoom
The transformer ratings are usually expressed in terms of______________?
A. amperes
B. volts
C. kW
D. kVA
An ideal transformer has infinite values of primary and secondary inductances. The statement is______________?
A. false
B. true
The chemical used in breather is_______________?
A. silica sand
B. asbestos fiber
C. sodium chloride
D. silica gel
The chemical used in breather for transformer should have the quality of____________?
A. cleansing the transformer oil
B. absorbing moisture
C. ionizing air
D. cooling the transformer oil
Transformers Mcqs
The use of higher flux density in the transformer design____________?
A. reduces weight per kVA
B. reduces copper losses
C. reduces iron losses
D. increases part load efficiency
In a transformer the tappings are generally provided on_____________?
A. secondary side
B. primary side
C. low voltage side
D. high voltage side
What will happen if the transformers working in parallel are not connected with regard to polarity ?
A. The transformers will not share load in proportion to their kVA ratings
B. Incorrect polarity will result in dead short circuit
C. The power factor of the two trans-formers will be different from the power factor of common load
D. none of the above
If the percentage impedances of the two transformers working in parallel are different, then______________________?
A. parallel operation will be not possible
B. power factors of both the transformers will be same
C. transformers will be overheated
D. parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load
If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be___________?
A. R22!K2
B. R2IK2
C. R2/VK
D. R22/K
Two transformers operating in parallel will share the load depending upon their____________?
A. efficiencies
B. per unit impedance
C. leakage reactance
D. ratings
The power transformer is a constant______________?
A. current device
B. voltage device
C. power device
D. main flux device
The purpose of providing iron core in a step-up transformer is?
A. to increase the magnitude of mutual flux
B. to provide coupling between primary and secondary
C. to decrease the magnitude of mag-netizing current
D. to provide all above features
Greater the secondary leakage flux____________?
A. less will be the secondary induced e.m.f.
B. less will be the primary terminal voltage
C. less will be the primary induced e.m.f.
D. none of the above
Spacers are provided between adjacent coils?
A. to provide free passage to the cooling oil
B. to insulate the coils from each other
C. both
D. none of the above
No-load current of a transformer has_____________?
A. has high magnitude and high power factor
B. has high magnitude and low power factor
C. has small magnitude and high power factor
D. has small magnitude and low power factor
Transformer breaths in when_______________?
A. load remains constant
B. load on it decreases
C. load on it increases
D. none of the above
The maximum efficiency of a distribution transformer is____________?
A. at 80% full load
B. at 50% full load
C. at no load
D. at full load
Power transformers are designed to have maximum efficiency at___________?
A. nearly full load
B. 50% full load
C. 70% full load
D. no load
Natural oil cooling is used for transformers up to a rating of____________?
A. 3000 kVA
B. 500 kVA
C. 1000 kVA
D. 250 kVA
In the transformer the function of a conservator is to_______________?
A. supply cooling oil to transformer in time of need
B. provide fresh air for cooling the transformer
C. protect the transformer from damage when oil expends due to heating
D. none of the above
In a transformer routine efficiency depends upon_____________?
A. supply frequency
B. power factor of load
C. load current
D. both B. and (c)
The no load current in a transformer lags behind the applied voltage by an angle of about_____________?
A. 120″
B. 180°
C. 90°
D. 75°
A common method of cooling a power transformer is_______________?
A. air blast cooling
B. natural air cooling
C. oil cooling
D. any of the above
In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are______________?
A. copper losses
B. friction and windage losses
C. hysteresis and eddy current losses
D. none of the above
Efficiency of a power transformer is of the order of________________?
A. 50 per cent
B. 98 per cent
C. 100 per cent
D. 25 per cent
Which winding in a transformer has more number of turns ?
A. Primary winding
B. High voltage winding
C. Low voltage winding
D. Secondary winding
Primary winding of a transformer________________?
A. is always a high voltage winding
B. is always a low voltage winding
C. could either be a low voltage or high voltage winding
D. none of the above
A transformer cannot raise or lower the voltage of a D.C. supply because_______________?
A. a D.C. circuit has more losses
B. there is no need to change the D.C. voltage
C. Faraday’s laws of electromagnetic induction are not valid since the rate of change of flux is zero
D. none of the above
A transformer transforms__________________?
A. current
B. voltage
C. power
D. frequency
In the transformer following winding has got more cross-sectional area______________?
A. Low voltage winding
B. Primary winding
C. High voltage winding
D. Secondary winding
While conducting short-circuit test on a transformer the following side is short circuited?
A. Primary side
B. Low voltage side
C. High voltage side
D. Secondary side
Which of the following is not a part of transformer installation ?
A. Breather
B. Conservator
C. Buchholz relay
D. Exciter
The purpose of providing an iron core in a transformer is to_____________?
A. reduce hysteresis loss
B. provide support to windings
C. decrease the reluctance of the magnetic path
D. reduce eddy current losses
No-load current in a transformer________________?
A. lags behind the voltage by about 75°
B. lags behind the voltage by about 15°
C. leads the voltage by about 75°
D. leads the voltage by about 15°
The efficiency of a transformer will be maximum when_____________?
A. hysteresis losses = eddy current losses
B. copper losses = hysteresis losses
C. eddy current losses = copper losses
D. copper losses = iron losses
The permissible flux density in case of cold rolled grain oriented steel is around__________?
A. 1.7 Wb/m2
B. 3.7 Wb/m2
C. 2.7 Wb/m2
D. 4.7 Wb/m2
Sumpner’s test is conducted on transformers to determine_____________?
A. temperature
B. all-day efficiency
C. stray losses
D. none of the above
The dielectric strength of transformer oil is expected to be______________?
A. 100 kV
B. 33 kV
C. lkV
D. 330 kV
The path of a magnetic flux in a transformer should have______________?
A. high reluctance
B. high resistance
C. low resistance
D. low reluctance
The no-load current drawn by transformer is usually what per cent of the full-load current ?
A. 12 to 15 per cent
B. 2 to 5 per cent
C. 0.2 to 0.5 per cent
D. 20 to 30 per cent
The degree of mechanical vibrations produced by the laminations of a transformer depends on____________?
A. gauge of laminations
B. tightness of clamping
C. size of laminations
D. all of the above
A transformer core is laminated to__________?
A. reduce copper losses
B. reduce eddy current losses
C. reduce hysteresis loss
D. reduce all above losses
In a transformer the energy is conveyed from primary to secondary_________?
A. through air
B. through cooling coil
C. by the flux
D. none of the above
Which of the following does not change in a transformer ?
A. Voltage
B. Current
C. Frequency
D. All of the above