Electrical Engineering · Question Bank
Transformers
110 of 258 questions match · page 3 of 6. Answer in your head first, then check the solution.
#41📘 EE Pocket Reviewer RojasEasy
The increased in the kVA capacity produced by connecting a two winding transformer as an autotransformer is due to which of the following?
AIncreased in the secondary voltage
BIncreased in the transformer efficiency
CIncreased in turns ratio
DEstablishment of a conductive link between primary and secondary
#42📘 EE Pocket Reviewer RojasEasy
What is the purpose of stampings in transformers?
ATo reduce the hysteresis loss
BTo reduce the eddy current loss
CTo reduce the copper loss
DAll of these
#43📘 EE Pocket Reviewer RojasEasy
The cores of transformers is normally made from which of the following materials?
ASilicon steel
BSeasoned wood
CAnnealed copper
DAluminum
#44📘 EE Pocket Reviewer RojasEasy
Which of the following is true about the primary and secondary induced emfs in a transformer?
AThey are always equal in magnitude
BThey are always anti-phase with each other
CThey are always in-phase with each other
DThey are always dependent on the load connected on the secondary side
#45📘 EE Pocket Reviewer RojasEasy
What is the purpose of a tap changing transformer?
ATo supply low voltage for instruments
BTo step up the voltage
CTo step down the voltage
DTo step up as well as step down the voltage
#46📘 EE Pocket Reviewer RojasEasy
Which one is an essential feature of an autotransformer?
AIt uses only one winding
BIt is more suited for single-phase supply
CIt is completely automatic in its operation
DIt is particularly suited for situations where the voltage transformation ratio exceeds unity
#47📘 EE Pocket Reviewer RojasEasy
The core of a transformer must posses which of the following characteristics?
ALow permeability and high hysteresis
BLow permeability and low hysteresis
CHigh permeability and low hysteresis
DHigh permeability and high hysteresis
#48📘 EE Pocket Reviewer RojasEasy
At what condition will the efficiency of a transformer be maximum?
AResistance of both windings are equal
BCopper loss is equal to core loss
CPer unit impedance of both windings are equal
DLoad served is a unity pf load
#49📘 EE Pocket Reviewer RojasEasy
Which of the following cannot be done by a transformer?
AIncrease the output power
BIncrease the output impedance
CIncrease the output voltage
DIncrease the output current
#50📘 EE Pocket Reviewer RojasEasy
What is the cause of the humming sound in a transformer?
ATransformer winding
BTransformer oil
CMagnetostriction
DSize of transformer tanks
#51📘 EE Pocket Reviewer RojasEasy
The all-day efficiency of a transformer is ____ commercial efficiency of the same transformer.
AEqual to
BLess than the
CGreater than the
DEither less than or greater than the
#52📘 EE Pocket Reviewer RojasEasy
Which loss will decrease when the load of transformer will decrease?
ACopper loss
BEddy current loss
CHysteresis loss
DAll of these
#53📘 EE Pocket Reviewer RojasEasy
What is the purpose of using a higher flux density in a transformer?
ATo decrease the weight per kVA
BTo increase the weight per kVA
CTo decrease the weight per kW
DTo increase the weight per kW
#54📘 EE Pocket Reviewer RojasEasy
The temperature rise in a transformer is directly proportional to which of the following?
ALeakage reactance
BSupply frequency
CApparent power
DReactive power
#55📘 EE Pocket Reviewer RojasEasy
In general, what is the most important point to monitor during the operation of a transformer?
APrimary voltage
BCore loss
CExciting current
DTemperature
#56📘 EE Pocket Reviewer RojasEasy
What is the percentage equivalent of the no load current in comparison to the full load current of a transformer?
AAbout 1 to 2%
BAbout 2 to 5%
CAbout 5 to 10%
DAbout 10 to 20%
#57📘 EE Pocket Reviewer RojasEasy
Which of the following will happen when a transformer is plugged into a DC circuit?
AIt would blow a fuse
BThe secondary will burn out
CThe primary will overload and the secondary will be dead
DAll of these
#58📘 EE Pocket Reviewer RojasEasy
Which of the following tests is used to determine the relative polarity of the windings of a transformer?
AShort circuit test
BPhasing out test
CBack to back test
DOpen circuit test
#59📘 EE Pocket Reviewer RojasEasy
When a closed A bank is converted into an open A bank, each of the two remaining transformers supplies what percent of the original load?
#60📘 EE Pocket Reviewer RojasEasy
Two transformers when operating in parallel will share the load depending on which of the following?
ALeakage reactance
BEfficiency
CPer unit impedance
DMagnetizing current
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