Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer 5
Electrical Engineering Objective Question and Answer
Electrical Transformer MCQs with Answers
81- An auto transformer has
(A) Only one winding
(B) Two windings of the same gauge of wiring
(C) two winding of different material
(D) more than two winding
Answer: (A)
82- Which of the following condition should be fulfilled for the parallel operation of two transformers?
(A) Percentage impedance should be the same
(B) polarities of both secondary should be same
(C) voltage ratings should be same
(D) all of the above
Answer: (D)
83- If the transformer core is made of copper
(A) Copper losses will be less
(B) eddy current losses will be more
(C) hysteresis losses will be more
(D) none of the above
Answer: (B)
84- If the ohmic resistance of windings of a transformer is zero, then
(A) Then there will be maximum magnetic leakage
(B) copper loss will be zero
(C) core loss will be more than copper loss
(D) transformer ratio will be infinite
Answer: (B)
85- If the secondary of a 5:1 step down transformer is connected to the primary of a 10:1 step down transformer, the total step ratio of transformation will be
(A) 5:1
(B) 10:1
(C) 50:1
(D) 2500:1
Answer: (C)
86- The efficiency of two identical transformers under load conditions can be determined by
(A) Back to back test
(B) open circuit test
(C) short circuit test
(D) any of above
Answer: (A)
87- Three to three phase transformer connection possible for parallel operation is
(A) ∆ - Y to Y - ∆
(B) ∆ - ∆ to ∆ - Y
(C) Y –Y to ∆ - Y
(D) Y- ∆ to ∆ - Y
Answer: (A)
88- Three to three phase transformer connection not feasible for parallel operation is
(A) ∆ - Y to Y - ∆
(B) ∆ - ∆ to ∆ - Y
(C) Y –Y to ∆ - Y
(D) Y- ∆ to ∆ - Y
Answer: (C)
89- When transformer operates under no load condition, the current
(A) Will lag the applied voltage by 90⁰
(B) will lag the applied voltage by 75⁰
(C) will lag the applied voltage by 75⁰
(D) Will be in phase with the applied voltage
Answer: (B)
90- The useful flux of a transformer is 1.2 Weber .when the transformer is loaded with at 0.8 p.f. Lagging, the mutual flux will be closer to
(A) 1.5 Weber
(B) 1.28 Weber
(C) 1.2 Weber
(D) 1.1 Weber
Answer: (D)
91- In an auto transformer, a break occurs at the point P, The value of V2 will be
(A) 200 V
(B) 100 V
(C) 50 V
(D) zero
Answer: (A)
92- Which of the following condition should be fulfilled for parallel operation of two transformers?
(A) Ratio of equivalent resistance and equivalent reactance should be same
(B) Turn ratio should be same
(C) percentage impedance should be same
(D) all of the above
Answer: (D)
93- If a transformer core is made up of copper and coil is made of steel wire, then
(A) Magnetizing current will be reduced
(B) copper losses in the winding will be more
(C) eddy current losses will be less
(D) all of the above
Answer: (B)
94- Which of the following loss in a transformer is zero even at full load?
(A) Eddy current loss
(B) hysteresis loss
(C) core loss
(D) friction loss
Answer: (D)
95- In a transformer for the waveform on primary as shown, the corresponding wave for secondary side is represented by the curve
(A) A
(B) B
(C) C
(D) D
Answer: (A)
96- Long Transmission of high voltages becomes possible because of
(A) capacitor
(B) inductor
(C) circuit breaker
(D) transformer
Answer: (D)
97- Transformer uses the principle of
(A) self induction
(B) Lenz law
(C) Newton law
(D) mutual induction
Answer: (D)
98-in a step up Transformer, the emf per turn on primary winding is
(A) the same as emf per turn of winding on secondary
(B) more than the emf per turn of winding on secondary side
(C) less than the emf per turn of winding on secondary side
(D) in the same ratio with emf on secondary as the voltage ratio
Answer: (A)
99- 1 Tesla is same
(A) 1 Weber
(B) 1 henry
(C) 1 Weber/
(D) 100 Weber/
Answer: (C)
100- As a general rule, the k VA rating ratio of transformers operating in parallel should be within
(A) 2:1
(B) 3:1
(C) 4:1
(D) 5:1
Answer: (B)
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