Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer Part 2
Electrical Engineering Objective Question and Answer
Electrical Transformer MCQs with Answers
21-A short circuit test on
transformer gives
(A) Copper
losses at full load
(B) copper losses at
half load
(C) iron losses at any load
(D) sum of iron losses and copper losses
Answer: (A)
22-Leakage fluxes in a transformer may be minimized by
(A) Sectionalizing
and interleaving the primary and secondary winding
(B) constantly cooling the core
(C) under rating the transformer
(D) reducing the reluctance of the iron core
to the minimum
Answer: (A)
23- Essential condition for
parallel operation of transformer is
(A) They must
have equal kVA ratings
(B) their voltage rating must be in proportion
to the load shared
(C) They must operate in same frequency
(D) their
ratio of transformation must be in proportion to the load shared
Answer: (C)
24 – A transformer having 100 turns
of primary side is applied with 200 V ac. In order to get 400 V ac on secondary
side the number of turns on the secondary side must be
(A) 200
(B) 800
(C) 50
(D) 100
Answer: (A)
25- Which of the following
transformers will be largest in size?
(A) 1 kVA,25
Hz
(B) 1 kVA,50 Hz
(C) 1
kVA,60 Hz
(D) 1 kVA,100 Hz
Answer: (D)
27- A step up transformer increases
(A) Power
(B) Power factor
(C) Voltage
(D) Frequency
Answer: (C)
28- In a
step down transformer
(A) Secondary turns are less than primary turns
(B) secondary power is less than primary
power
(C) phase shift is always 180
(D) Secondary current is always more than
primary current
Answer: (A)
29-A transformer has full load iron
loss of 900 W and copper loss of 1600 W. At What percent of load, the
transformer will have maximum efficiency?
(A) 100%
(B) 90%
(C) 75%
(D) 50%
Answer: (C)
30- Power transformer are usually designed to have maximum
efficiency
(A) Near full
load
(B) near 75% of load
(C) near 50% of load
(D) near no load
Answer: (A)
31-iron losses of a transformer can be approximately
calculated if
(A) The gauge
of the sheet used in the core is known
(B) the material of core and yoke is known
(C) the weight of the core and yoke is known
(D) the shape of yoke and core is known
Answer: (C)
32- Distribution transformer are
usually designed to have maximum efficiency
(A) Near full
load
(B) near 75% of load
(C) near 50% of load
(D) near no load
Answer: (C)
33- In high frequency
transformers,
(A) Carbon
cores are used
(B) Wooden cores are
used
(C) ferrite cores are used
(D) aluminum cares are used
Answer: (C)
34- In a transformer it is
difficult to measure the efficiency by output –input measurement methods
because
(A) The output
is sinusoidal and hence cannot be
measured
(B) losses are
abnormally high
(C) efficiency of a
transformer is usually high and hence extremely accurate measurements will be
necessary
(D) output is out of phase
with respect to the input
Answer: (C)
A 600
kVA, single phase transformer when working at unity power factor has an
efficiency of 92% at full load and also at half load
35- Total losses at full load are
(A) 104.4 kW
(B) 48 kW
(C) 52.2 kVA
(D) 26.1 kW
Answer: (C)
36- Total losses at half load are
(A) 52.2 kW
(B)
52.2 kVA
(C) 26.1 kVA
(D) 24 kW
Answer: (C)
37- What will be efficiency when
the transformer operates at unity power factor and 60% of full load?
(A) 99%
(B)
96.5%
(C) 93.3%
(D) 91.8%
Answer: (B)
38- Open circuit test on transformer yields?
(A) Core losses
(B) copper losses
(C) sum of core and copper losses
(D) leakage reactance
Answer: (A)
39- The leakage flux in a
transformer depends upon
(A) Load
current
(B) load current and
voltage
(C) load current ,voltage and
frequency
(D) load current .voltage
,frequency and power factor
Answer: (A)
40- Which of the following is not a
routine test on transformers?
(A) Polarity
test
(B) radio interference test
(C) core insulation voltage test
(D) impedance test
Answer: (B)
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