ELECTRICIAN- Transformers MCQ

Prepare for your examinations with a set of multiple choice questions (MCQs) related to Transformers for Electrician Trade. The questions are likely designed to test a user’s knowledge or understanding of electrical concepts and may be useful for exam preparation or self-assessment. The website may be a helpful resource for individuals studying to become electricians or seeking to improve their understanding of electrical principles.

TRANSFORMER

Which type of transformer is used for high frequency application?Ring core transformerFerrite core transformerSilicon steel core transformerGrain oriented core transformer

What is the function of conservator in transformer?Prevents the moisture entryTransfers the heat to atmosphereAllows to release internal pressureAllows expansion of oil level due to load variation

Which loss of transformer is determined by short circuit test?Copper lossWindage lossHysteresis lossEddy current loss

Calculate the voltage regulation in percentage of the transformer if the no load voltage is 240 volt and full load voltage is 220 volt?7.2 %8.3 %8.71%9.09%

What is the purpose of using laminated core in transformer?Reduce copper lossReduce hysteresis lossReduce mechanical lossReduce eddy current loss

What is the cooling method of transformer?

Oil natural coolingOil natural air forced coolingOil forced air forced coolingOil natural water forced cooling

What is the condition for obtaining maximum efficiency from transformer?Copper loss > Iron lossCopper loss < Iron lossCopper loss = Iron lossCopper loss =Eddy current loss

What is the function of top float switch of buchholz relay in transformer?Activate in moisture presenceActivate at overloading conditionActivate at open circuit conditionActivate at high temperature condition

Why the core of current transformer is having low reactance and low core losses?To minimise the burdenTo maintain constant outputTo prevent high static shieldTo minimise the error in reading

How the error in reading of a potential transformer can be reduced?Using thin laminated coreProviding long magnetic pathUsing high flux density materialProviding good quality core material

Why the load is disconnected before the OFF load tap changing operation?To disconnect the tappings from neutral pointTo disconnect the moving contact of the diverterTo avoid heavy sparking at the contact pointsTo provide an electrical isolation for the windings

Which condition is absolutely essential for parallel operation of two transformers?Nature of loadType of coolingPhase sequenceClass of insulation used

Which construction technique is used to reduce copper loss in larger transformers?Use of laminated coreBy reducing core thicknessBy using grain oriented coreUse stepped core arrangement

Which transformer is used to measure high voltage installations?Pulse transformersIgnition transformersPotential transformersConstant voltage transformers

How does the moisture is controlled in breather fitted on power transformers?Using silica gelUsing transformer oilUsing sodium chlorideUsing ammonium jelly

Which power loss is assessed by open-circuit test on transformer?Hysteresis loss onlyEddy current loss onlyCopper lossCore loss

Which is determined by the crackle test of transformer oil?AcidityMoistureViscosityDielectric strength

Which material is used to make core of power transformer?Soft ironRolled steelCopper alloyCold rolled grain oriented

What is the name of transformer?

Auto transformerCore type transformerShell type transformerAudio frequency transformer

What is the purpose of providing explosion vent in a power transformer?Air releasingHeat releasingPressure releasingMoisture releasing

What is the function of buchholz relay in power transformer?Protection from high temperatureProtection from moisture entering in oilProtection from pressure loading in tankProtection from both overloading and short circuit

Why primary of potential transformer is wound with thin wire and large number of turns?To offer high inductanceTo obtain required voltage ratioTo regulate the primary currentTo stabilise input and output voltage

Why distribution transformers are normally connected as primary in delta and secondary in star?To avoid overloadingTo maintain constant voltageTo reduce transformer lossesTo easy distribution of 3 phase 4 wire system

Which type of emf is induced in an ideal two winding transformer?Self induced emfMutually induced emfStatically induced emfDynamically induced emf

How to determine copper loss in a transformer?Ratio testImpulse testShort circuit testOpen circuit test

Why ferrite core is used in radio receivers?To reduce the constant lossesTo reduce electric interferenceTo increase the quality of soundTo increase the efficiency of receivers

What is the advantage of stepped core arrangement in larger transformers?Minimizes copper useReduces hysteresis lossReduces eddy current lossReduces the space for core

Which material is used in breather to prevent moisture entering in the transformer oil?Silica gelSodium chlorideAmmonium chlorideCharcoal and salt mixture

What is the disadvantage of auto transformer?More lossesHeavier in weightPoor voltage regulationCannot isolate the secondary winding

Which cooling method is used in pole mounting distribution transformer?Air naturalOil natural air blastOil forced air forcedOil natural air natural

What is the composition of steel and silicon steel in transformer core?Steel 90% and silicon 10%Steel 97% and silicon 3%Steel 95% and silicon 5%Steel 93% and silicon 7%

What is the purpose of tap changing in power transformers?Change voltage ratio in distributionChange voltage ratio in distributionMaintain secondary voltage constantLoad the transformer for maximum efficiency