Transformer Questions PDF

The function of a transformer is to: a) Change the level of DC voltage b) Change the level of AC voltage c) Change the frequency of AC voltage d) Change AC to DC voltage Type of machine that produces the static induced emf is: a) Generator b) Motor c) Transformer d) Rectifier The power transformer...

The function of a transformer is to: a) Change the level of DC voltage b) Change the level of AC voltage c) Change the frequency of AC voltage d) Change AC to DC voltage Type of machine that produces the static induced emf is: a) Generator b) Motor c) Transformer d) Rectifier The power transformer is a constant: a) Current device b) Voltage device c) Main flux device d) Frequency device A transformer works on: a) DC only b) A.C. only c) Both AC and DC d) None of the above The rating of a transformer is expressed in: a) kW b) kVA c) kWh d) Amps A transformer steps up or down: a) DC only b) A.C. only c) Both AC and DC d) Frequency only The transformer equation V1I1 = V2I2 is the manifestation of: a) Ohm’s Law b) Kirchhoff’s Law c) Law of energy conservation d) Coulomb’s Law In a step-up transformer: a) Ns = Np b) Ns < Np c) Ns > Np d) Ns ≠ Np In a step-down transformer: a) Ns = Np b) Ns < Np c) Ns > Np d) Ns ≠ Np The magnitude of the induced emf in the primary winding will be ______ but opposite to the applied voltage: a) Higher b) Lower c) Almost equal d) Zero In a transformer, the resistance between its primary and secondary is: a) Zero b) Finite c) Infinite d) Variable A transformer converts voltage and current level without change in: a) Current b) Voltage c) Frequency d) Power The changes in voltage levels in the power system are provided by using: a) Resistor b) Capacitor c) Inductor d) Transformer ______ are used as an insulation medium in a transformer: a) Air and Water b) Insulating oil and Insulating paper c) Rubber and Plastic d) Air and Rubber The advantages of a single three-phase transformer bank over three single-phase transformer banks are: a) Higher efficiency b) Cost is less, it weighs less, and it occupies less space for the same rating c) Better cooling d) Easier maintenance In a three-phase transformer compared to a single-phase transformer: a) It takes more space b) It has a three-limbed core, it takes less space, it is cheaper, it is slightly more efficient c) It is less efficient d) It has a higher loss A transformer transforms: a) Power only b) Voltage and current c) Voltage only d) Current only ______ parameter does not change during transformation action in a transformer: a) Voltage b) Current c) Power d) Frequency The magnitude of magnetic flux in a transformer: a) Increases with load b) Decreases with load c) Is same at all loads d) Varies with voltage An electric transformer is: a) An electric device that converts DC to AC b) An electric device that consists of two or more multi-turn coils wound on a common core c) A rotating device d) A capacitor device Compared to the secondary of a loaded step-up transformer, the primary has: a) Higher voltage and higher current b) Lower voltage and higher current c) Lower voltage and lower current d) Higher voltage and lower current If the AC supply to the transformer is replaced by DC: a) The transformer will work as usual b) The secondary winding will burn c) The primary winding will burn d) Both windings will burn The HT winding of a 3-phase step-down transformer is wound with: a) Fewer turns of thick wire b) More number of turns of thick wire c) More number of turns of relatively thin wire d) Fewer turns of thin wire In a power transformer: a) High voltage winding is always wound with fewer turns of thicker wire b) Low voltage winding is always wound with fewer turns of thicker wire c) Both windings have the same number of turns d) Both windings have the same wire thickness A transformer, as compared to an amplifier, cannot increase: a) Voltage b) Current c) Power d) Frequency In a transformer, the energy is conveyed from primary to secondary: a) By the windings b) By the flux c) By the insulation d) By the core In a transformer, the winding to which electric supply is given as input is called: a) Secondary winding b) Primary winding c) Tertiary winding d) Auxiliary winding Primary winding of a transformer: a) Is always low voltage b) Is always high voltage c) Could be either low voltage or high voltage d) Is always equal to secondary voltage The function of a transformer is not: a) To step up or step down voltage b) To convert DC into AC c) To transfer electrical energy d) To isolate circuits A transformer does not possess ______ changing property: a) Voltage b) Current c) Power d) Frequency The winding of a step-up transformer with more turns is: a) Low voltage winding b) High voltage winding c) Primary winding d) Secondary winding The phase relationship between primary and secondary terminal voltage of a transformer is: a) 0 degrees out of phase b) 90 degrees out of phase c) 180 degrees out of phase d) 360 degrees out of phase In a transformer, the frequency of the secondary voltage will be: a) Higher than the primary voltage b) Lower than the primary voltage c) Equal to the primary voltage d) Variable A step-up transformer: a) Decreases secondary voltage b) Increases secondary voltage c) Increases primary voltage d) Decreases primary voltage A transformer is a device which converts: a) Low voltage high current into high voltage low current and vice versa b) High voltage low current into low voltage high current only c) AC to DC d) DC to AC A transformer works on the principle of: a) Lenz’s law b) Ohm’s law c) Faraday's laws of electromagnetic induction d) Ampere's law ______ principle makes the instrument transformer working: a) Electrostatic induction b) Electromagnetic induction c) Self-induction d) Mutual induction The function of a transformer is to transform: a) Voltage and current at fixed power level b) Power and frequency c) Frequency and current d) Voltage and frequency A transformer cannot raise or lower the voltage of a D.C. supply because: a) DC supply has zero voltage b) DC supply has no current c) Faraday's laws of electromagnetic induction is not valid since the rate of change of flux is zero d) Transformers are not designed for DC Transformers are devices which transform electrical energy from one electrical circuit to another. These two circuits are: a) Electrically connected b) Not electrically connected c) Connected by a resistor d) Connected by a capacitor If a two-winding transformer of a given volt-ampere rating is connected as an autotransformer, then it can handle: a) Lower volt-ampere b) Higher volt-ampere c) Same volt-ampere d) Variable volt-ampere In a transformer, magnetic coupling between the primary & secondary circuit can be increased by: a) Using an air core b) Using a magnetic core of high reluctance c) Using a magnetic core of low reluctance d) Increasing the distance between windings Two windings of a transformer are designed as: a) Primary and Tertiary windings b) Secondary and Tertiary windings c) HV and LV windings d) Primary and Auxiliary windings The primary and secondary windings of a transformer are: a) Electrically linked b) Inductively linked c) Conductively linked d) Magnetically isolated Power transformed from continue ChatGPT primary to secondary depends upon: a) Voltage difference between primary and secondary b) Current difference between primary and secondary c) Magnetic coupling between primary and secondary windings d) Electrical resistance of windings The mutual flux in a loaded transformer can be varied by varying: a) Voltage applied b) Current flowing c) Reluctance of the magnetic path d) Frequency of supply The two windings of a transformer have an inductance of 2H each. If the mutual inductance between them is also 2H, then: a) It is a perfect transformer b) It is an imperfect transformer c) It is an ideal transformer d) It is a real transformer A transformer operates: a) At a power factor depending on the power factor of the load b) Always at unity power factor c) Always at zero power factor d) Always at 0.5 power factor A shell-type transformer has _____ limbs and _____ yoke: a) 2, 1 b) 1, 2 c) 3, 2 d) 2, 3 Core type transformer has _____ yoke and _____ limb: a) 1, 2 b) 2, 1 c) 2, 3 d) 1, 3 Core type transformers are more suitable for: a) Low voltage and high output b) High voltage and low output c) High voltage and high output d) Low voltage and low output There are _____ magnetic paths in the core type transformer: a) One b) Two c) Three d) Four There are _____ magnetic paths in the shell type transformer: a) One b) Two c) Three d) Four A shell-type transformer has: a) Increased magnetic leakage b) Reduced magnetic leakage c) No magnetic leakage d) High magnetic leakage In a shell-type single-phase transformer: a) The core has two limbs b) The coils are of cylindrical type c) The coils are of multi-layer disc type or sandwich type d) The core has one limb Distribution transformers have the rating of: a) Up to 100 kVA b) Up to 500 kVA c) Up to 200 kVA d) More than 200 kVA For higher voltage ranges _____ transformers are used: a) Core type b) Shell type c) Autotransformers d) Distribution transformers For low voltage and large kVA _____ transformers are used: a) Core type b) Shell type c) Autotransformers d) Power transformers In a core type single-phase transformer: a) A core is circular in shape b) The core is rectangular in shape of unicrosssection c) Coils are wound in a spiral form d) Coils are wound in a parallel form The use of higher flux density in the transformer design is for: a) Decreasing the weight/kVA b) Increasing the weight/kVA c) Decreasing the cost d) Increasing the cost Rectangular frame lamination are formed to build the interior of the transformer which are cut in L-shape strip to avoid high reluctance at joints in: a) Core type transformer b) Shell type transformer c) Autotransformers d) Power transformers A _____ is a substation that has no transformer and operates only at a single voltage level: a) Switching station b) Distribution station c) Power station d) Generating station The vertical position on which the coil is wound in a transformer is called: a) Core b) Yoke c) Limb d) Winding _____ is not a characteristic of a transformer: a) High efficiency b) Electrically coupled windings c) Rugged construction d) No moving parts The degree of mechanical vibrations produced by the laminations of a transformer depends on: a) Voltage applied b) Frequency of operation c) Tightness of clamping, gauge of laminations, size of laminations d) Current flowing Material used while making the core of the transformer to reduce hysteresis loss is: a) Copper b) Aluminum c) Silicon steel d) Iron Characteristics of a transformer are: a) Very high efficiency, it has no moving parts, rugged in construction b) High efficiency, it has moving parts, fragile in construction c) Low efficiency, it has no moving parts, rugged in construction d) Low efficiency, it has moving parts, fragile in construction The most vital condition to be ensured throughout the period of drying out of a transformer (which usually takes 3 to 4 weeks for a large transformer) is: a) The winding temperature should never exceed 90ºC b) The core temperature should never exceed 90ºC c) The oil temperature should never exceed 90ºC d) The ambient temperature should never exceed 90ºC Answers: b) Change the level of AC voltage c) Transformer c) Main flux device b) A.C. only b) kVA b) A.C. only c) Law of energy conservation c) Ns > Np b) Ns < Np c) Almost equal c) Infinite c) Frequency d) Transformer b) Insulating oil and Insulating paper b) Cost is less, it weighs less, and it occupies less space for the same rating b) It has a three-limbed core, it takes less space, it is cheaper, it is slightly more efficient b) Voltage and current d) Frequency c) Is same at all loads b) An electric device that consists of two or more multi-turn coils wound on a common core b) Lower voltage and higher current c) The primary winding will burn c) More number of turns of relatively thin wire b) Low voltage winding is always wound with fewer turns of thicker wire c) Power b) By the flux b) Primary winding c) Could be either low voltage or high voltage b) To convert DC into AC c) Power b) High voltage winding c) 180 degrees out of phase c) Equal to the primary voltage b) Increases secondary voltage a) Low voltage high current into high voltage low current and vice versa c) Faraday's laws of electromagnetic induction d) Mutual induction a) Voltage and current at fixed power level c) Faraday's laws of electromagnetic induction is not valid since the rate of change of flux is zero b) Not electrically connected b) Higher volt-ampere c) Using a magnetic core of low reluctance c) HV and LV windings b) Inductively linked c) Magnetic coupling between primary and secondary windings c) Reluctance of the magnetic path a) It is a perfect transformer a) At a power factor depending on the power factor of the load c) 3, 2 a) 1, 2 b) High voltage and low output a) One b) Two b) Reduced magnetic leakage c) The coils are of multi-layer disc type or sandwich type c) Up to 200 kVA a) Core type b) Shell type b) The core is rectangular in shape of unicrosssection a) Decreasing the weight/kVA a) Core type transformer a) Switching station c) Limb b) Electrically coupled windings c) Tightness of clamping, gauge of laminations, size of laminations c) Silicon steel a) Very high efficiency, it has no moving parts, rugged in construction c) The oil temperature should never exceed 90ºC