Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer Part 10
Electrical Engineering Objective Question and Answer
181- For the Step up transformer shown in figure, the current through two portions of winding will be
(A) 9 A ,27 A
(B) 12 A, 24 A
(C) 20 A , 10 A
(D) 6 A , 6 A
Answer: (A)
Question 182 to 184 refer to data given below :
Two coils are wound on Bakelite Core. The primary coil has Lp = 60 mH and the secondary coil has Ls = 2.4 mH. The Coils are arranged so that k = 0.08
182- The mutual inductance M will be
Answer: (A)
Question 182 to 184 refer to data given below :
Two coils are wound on Bakelite Core. The primary coil has Lp = 60 mH and the secondary coil has Ls = 2.4 mH. The Coils are arranged so that k = 0.08
182- The mutual inductance M will be
(A) 1 mH
(B) 0.96 mH
(C) 0.75 mH
(D) 0.5 mH
Answer: (B)
182- When Primary current is decreasing at a rate of 104 A/S.the magnitude of induced secondary voltage will be
Answer: (B)
182- When Primary current is decreasing at a rate of 104 A/S.the magnitude of induced secondary voltage will be
(A) 4.8 V
(B)7.2 V
(C) 9.6 V
(D) 19.2 V
Answer: (C)
184- The rms value of Es when Ep = 15 V at 1 MHz will be
Answer: (C)
184- The rms value of Es when Ep = 15 V at 1 MHz will be
(A) 0.24 V
(B) 0.96 V
(C) 1.8 V
(D) 2.4 V
Answer: (A)
185- Which of the following can be reduced when the flux density in the transformer core is increased ?
Answer: (A)
185- Which of the following can be reduced when the flux density in the transformer core is increased ?
(A) Size of the transformer
(B) Output frequency
(C) Wave shape distortion
(D) copper losses
Answer: (A)
186- in three phase transformer, the phase difference between the primary and the induced secondary winding is
Answer: (A)
186- in three phase transformer, the phase difference between the primary and the induced secondary winding is
(A) 90°
(B) 120°
(C) 180°
(D) 360°
Answer: (C)
187- when the transformer core is made of copper, which of the following loss will be more ?
Answer: (C)
187- when the transformer core is made of copper, which of the following loss will be more ?
(A) copper loss
(B) Hysteresis loss
(C) thermal loss
(D) Eddy current loss
Answer: (D)
Answer: (D)
188- Porcelain bushing on transformer are normally not used beyond
(A) 11 kV
(B) 66 kV
(C) 132 kV
(D) 220 kV
Answer: (A)
Answer: (A)
189- In Scott connection the neutral point divides the winding of the teaser transformer in the ratio of
(A) 1 : 1
(B) 1 : 2
(C) 1 : 3
(D) 1 : 4
Answer: (B)
190- The secondary of a current transformer under operating conditions is short circuited to avoid
Answer: (B)
190- The secondary of a current transformer under operating conditions is short circuited to avoid
(A) break in primary winding
(B) insulation break down
(C) Core saturation and high voltage induction
(D) high voltage surge
Answer: (C)
Answer: (C)
191- Which of the following test can be used to determine the efficiency of two identical transformer at full load
(A) Open circuit test
(B) Short circuit test
(C) Type tests
(D) Back to back test
Answer: (D)
Answer: (D)
192- The inductive reactacne of a transformer depends on
(A) electromotive force
(B) magneto motive force
(C) magnetic flux
(D) leakage flux
Answer: (D)
Answer: (D)
193- Which of the following prevents damage to a transformer due to lightning and switching ?
(A) Buchholz relay
(B) Conservator
(C) Breather
(D) Horn gap
Answer: (D)
Answer: (D)
194- The voltage regulation of transformer can be zero, when the power factor is
(A)Unity
(B) 0.5
(C) leading
(D) lagging
Answer: (C)
195- The harmonic currents in transformer increase all of the following Except:
Answer: (C)
195- The harmonic currents in transformer increase all of the following Except:
(A) Copper Loss
(B) Core Loss
(C) Magnetic interference with protective relays
(D) Secondary voltage
Answer: (D)
196- The value of useful flux least depends on
Answer: (D)
196- The value of useful flux least depends on
(A) magneto motive force
(B) voltage
(C) load
(D) all of the above
Answer: (C)
197- The operation of an ideal voltage transformer is on which of the following assumptions ?
Answer: (C)
197- The operation of an ideal voltage transformer is on which of the following assumptions ?
(A) Negligible resistance
(B) No leakage flux
(C) Non- saturation of core
(D) All of the above
Answer: (D)
198- In which of the following transformer part of primary winding also serves as the secondary winding
Answer: (D)
198- In which of the following transformer part of primary winding also serves as the secondary winding
(A) Step up transformer
(B) current transformer
(C) Potential transformer
(D) Auto transformer
Answer: (D)
199- The characteristics of a voltage transformer are
Answer: (D)
199- The characteristics of a voltage transformer are
(A)current and voltage both vary with load
(B) voltage remaining constant , current varies with load
(C) current remaining constant, voltage varies with load
(D) current and voltage remain constant power factor varies with load
Answer: (B)
200- when a star- delta transformer bank of three single phase transformers is to be used for step down transformation with line voltages of 23000 V and 2300 V , the ratio of transformation will be
Answer: (B)
200- when a star- delta transformer bank of three single phase transformers is to be used for step down transformation with line voltages of 23000 V and 2300 V , the ratio of transformation will be
(A) 17.2 : 1
(B) 12.1 : 1
(C) 10 : 1
(D) 5.8 : 1
Answer: (D)
Answer: (D)
