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The no load current in a transformer lags behind the applied voltage by an angle of about?
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Mar 19, 2018
by
anonymous
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Mar 19, 2018
by
anonymous
The no load current in a transformer lags behind the applied voltage by an angle of about
75°.
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asked
Mar 19, 2018
by
anonymous
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?
Last answer:
In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.
transformer
voltage
losses
constant
load
changes
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asked
Mar 19, 2018
by
anonymous
No-load current in a transformer?
Last answer:
No-load current in a transformer lags behind the voltage by about 75°.
transformer
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asked
Mar 19, 2018
by
anonymous
No-load current of a transformer has?
Last answer:
No-load current of a transformer has small magnitude and low power factor.
transformer
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asked
Apr 28, 2020
by
anonymous
Even at no-load, a transformer draws current from the mains. Why?
Even at no-load, a transformer draws current from the mains. Why?
even
at
no-load
a
transformer
draws
current
from
the
mains
why
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answers
asked
Mar 19, 2018
by
anonymous
In an actual transformer the iron loss remains practically constant from no load to full load because?
Last answer:
In an actual transformer the iron loss remains practically constant from no load to full load because core flux remains practically constant.
transformer
iron
loss
constant
load
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asked
Apr 30, 2018
by
anonymous
The inrush current of a transformer at no load is maximum if the supply voltage is switched on
The inrush current of a transformer at no load is maximum if the supply voltage is switched on (1) at peak voltage value (2) at zero voltage value (3) at half voltage value (4) at 0.866 time voltage value
Last answer:
At 0.866 time voltage value
inrush
current
transformer
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asked
Mar 19, 2018
by
anonymous
A no-load test is performed on a transformer to determine?
A no-load test is performed on a transformer to determine?
Last answer:
A no-load test is performed on a transformer to determine magnetizing current and loss.
no-load
test
transformer
determine
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asked
Mar 19, 2018
by
anonymous
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of?
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of?
Last answer:
In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of less than 15A.
step-down
transformer
load
current
change
supply
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asked
Sep 27, 2017
by
anonymous
in open circuit or no load test of transformer which side is low voltage side and which side is high voltage side?
Last answer:
Primary side is low voltage side and secondary side is high voltage side.
open
circuit
test
transformer
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asked
Apr 28, 2018
by
anonymous
A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and
A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are (A) 140 W (B) 180 W (C) 240 W (D) 480 W
Last answer:
A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are 240 W
transformer
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asked
Mar 19, 2018
by
anonymous
For a transformer, operating at constant load current, maximum efficiency will occur at?
For a transformer, operating at constant load current, maximum efficiency will occur at?
Last answer:
For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.
transformer
operating
constant
load
current
maximum
efficiency
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asked
Mar 19, 2018
by
anonymous
The maximum load that a power transformer can carry is limited by its?
The maximum load that a power transformer can carry is limited by its?
Last answer:
The maximum load that a power transformer can carry is limited by its voltage ratio.
maximum
load
power
transformer
carry
limited
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asked
Mar 19, 2018
by
anonymous
In a power or distribution transformer about 10 percent end turns are heavily insulated?
Last answer:
In a power or distribution transformer about 10 percent end turns are heavily insulated to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns.
power
distribution
transformer
turns
heavily
insulated
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asked
Mar 19, 2018
by
anonymous
An ideal transformer will have maximum efficiency at a load such that?
Last answer:
An ideal transformer will have maximum efficiency at a load such that copper loss equal to iron loss.
ideal
transformer
maximum
efficiency
load
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asked
Mar 27, 2018
by
anonymous
The no-load current drawn by transformer is usually what per cent of the full-load current ?
The no-load current drawn by transformer is usually what per cent of the full-load current ?
Last answer:
5 to 8 percentage of full load current
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asked
Sep 27, 2017
by
anonymous
in open circuit or no load test of transformer which side is open circuited?
Last answer:
High Voltage side is open circuited.
transformer
open
circuit
test
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asked
Mar 19, 2018
by
anonymous
The full-load copper loss of a transformer is 1600 W At half-load, the copper loss will be?
Last answer:
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be 400 W.
transformer
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asked
Mar 19, 2018
by
anonymous
The purpose of providing an iron core in a transformer is to?
Last answer:
The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.
transformer
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asked
Jun 18, 2018
by
anonymous
An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to
An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V
Last answer:
An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having primary to secondary turn’s ratio 12:1. The peak inverse voltage is A) 8.62 V B) 12 V C) 19.17 V D) 27.11 V
ac
supply
half-wave
rectifier
circuit
transformer
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asked
Jul 27, 2019
by
anonymous
State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation
State and justify which of the following two transformers is better: Transformer A = 4% voltage regulation Transformer B = 6% voltage regulation
Last answer:
Transformer A with 4% voltage regulation is better. Justification: Voltage regulation refers to the percentage change in secondary voltage when load is changed from no-load to full-load with primary voltage ... 4% voltage regulation, which is less as compared to 6% of transformer B, it is better.
transformer
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asked
Mar 19, 2018
by
anonymous
A transformer cannot raise or lower the voltage of a D.C. supply because?
Last answer:
A transformer cannot raise or lower the voltage of a D.C. supply because Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero.
transformer
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1
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asked
Mar 19, 2018
by
anonymous
The voltage transformation ratio of a transformer is equal to the ratio of?
The voltage transformation ratio of a transformer is equal to the ratio of?
Last answer:
The voltage transformation ratio of a transformer is equal to the ratio of secondary induced e.m.f. to primary induced e.m.f.
voltage
transformation
ratio
transformer
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1
answer
asked
Mar 19, 2018
by
anonymous
The magnetising current of a transformer is usually small because it has?
Last answer:
The magnetising current of a transformer is usually small because it has small air gap.
transformer
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asked
Mar 19, 2018
by
anonymous
The secondary of a current transformer is always short-circuited under operating conditions because it?
The secondary of a current transformer is always short-circuited under operating conditions because it?
Last answer:
The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.
secondary
current
transformer
short-circuited
operating
conditions
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1
answer
asked
Mar 19, 2018
by
anonymous
A good voltage regulation of a transformer means?
A good voltage regulation of a transformer means?
Last answer:
A good voltage regulation of a transformer means output voltage fluctuation from no load to full load is least.
good
voltage
regulation
transformer
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1
answer
asked
Mar 19, 2018
by
anonymous
If a transformer is switched on to a voltage more than the rated voltage?
If a transformer is switched on to a voltage more than the rated voltage?
Last answer:
If a transformer is switched on to a voltage more than the rated voltage its power factor will deteriorate.
transformer
switched
voltage
rated
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asked
Mar 19, 2018
by
anonymous
When secondary of a current transformer is open-circuited its iron core will be?
When secondary of a current transformer is open-circuited its iron core will be?
Last answer:
When secondary of a current transformer is open-circuited its iron core will be hot because of heavy iron losses taking place in it due to high flux density.
secondary
current
transformer
open-circuited
iron
core
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1
answer
asked
Mar 19, 2018
by
anonymous
When a given transformer is run at its rated voltage but reduced frequency, its?
Last answer:
When a given transformer is run at its rated voltage but reduced frequency, its core flux density is increased.
transformer
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1
answer
asked
Mar 19, 2018
by
anonymous
Iron loss of a transformer can be measured by?
Last answer:
Iron loss of a transformer can be measured by low power factor wattmeter.
iron
loss
transformer
measured
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asked
Mar 19, 2018
by
anonymous
The noise produced by a transformer is termed as?
The noise produced by a transformer is termed as?
Last answer:
The noise produced by a transformer is termed as hum.
noise
produced
transformer
termed
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asked
May 22, 2020
by
anonymous
State why a transformer always have an efficiency of more than 90%.
State why a transformer always have an efficiency of more than 90%.
Last answer:
As transformer is static device with no moving parts, the losses due to friction & windage are completely absent. Hence transformer has efficiency of more than 90%.
transformer
efficiency
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asked
May 17, 2018
by
anonymous
A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit
A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit test is performed on it with 90% of the rated currents flowing in its both LV and HV windings, he measured loss is 81 W. The transformer has maximum efficiency when operated at (A) 50.0% of the rated current (B) 64.0% of the rated current (C) 80.0% of the rated current (D) 88.8% of the rated current
Last answer:
A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit test is performed on it with 90% of the rated currents flowing in its both ... measured loss is 81 W. The transformer has maximum efficiency when operated at 80.0% of the rated current
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asked
Mar 19, 2018
by
anonymous
An open-circuit test on a transformer is conducted primarily to measure?
An open-circuit test on a transformer is conducted primarily to measure?
Last answer:
The open-circuit test in a transformer is used to measure
open-circuit
test
transformer
conducted
primarily
measure
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271
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2
answers
asked
May 17, 2018
by
anonymous
Under no load condition, if the applied voltage to an induction motor is reduced from the rated voltage to
Under no load condition, if the applied voltage to an induction motor is reduced from the rated voltage to half the rated value, (A) the speed decreases and the stator current increases (B) both the speed and the stator current decreases (C) the speed and the stator current remain practically constant (D) there is negligible change in the speed but the stator current decreases
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asked
Mar 19, 2018
by
anonymous
Atmospheric temperature during day and night is taken care of by which part of the transformer?
The changes in the volume of transformer cooling oil due to the variation of atmospheric temperature during day and night is taken care of by which part of the transformer?
Last answer:
The changes in the volume of transformer cooling oil due to the variation of atmospheric temperature during day and night is taken care of by conservator.
transformer
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1
answer
asked
Mar 19, 2018
by
anonymous
An ideal transformer has infinite values of primary and secondary inductances. The statement is?
Last answer:
An ideal transformer has infinite values of primary and secondary inductances. The statement is false.
transformer
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134
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1
answer
asked
Apr 30, 2018
by
anonymous
A transformer has negative voltage regulation when its load power factor is
A transformer has negative voltage regulation when its load power factor is (1) Zero (2) Unity (3) Leading (4) Lagging
Last answer:
Leading
transformer
negative
voltage
regulation
load
power
factor
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1.1k
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2
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asked
Mar 19, 2018
by
anonymous
The transformer laminations are insulated from each other by?
Last answer:
The transformer laminations are insulated from each other by thin coat of varnish.
transformer
lamination
insulated
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1
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asked
Mar 19, 2018
by
anonymous
An ideal transformer is one which has?
Last answer:
An ideal transformer is one which has no losses and magnetic leakage.
transformer
ideal
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68
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1
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asked
Mar 19, 2018
by
anonymous
The purpose of providing iron core in a step-up transformer is?
Last answer:
The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.
transformer
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279
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1
answer
asked
Mar 19, 2018
by
anonymous
The thickness of laminations used in a transformer is usually?
Last answer:
The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.
transformer
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1
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asked
Mar 19, 2018
by
anonymous
The function of conservator in a transformer is?
Last answer:
conservator or a reservoir tank for insulating oil in transformer which used for balanced the onload oil level with help of oil level indicator which mount on middle part of reservoir tank.
transformer
conservator
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104
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3
answers
asked
Mar 19, 2018
by
anonymous
The main reason for generation of harmonics in a transformer could be?
Last answer:
The main reason for generation of harmonics in a transformer could be saturation of core.
transformer
harmonics
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1
answer
asked
Mar 19, 2018
by
anonymous
The value of flux involved in the e.m.f. equation of a transformer is ?
Last answer:
The value of flux involved in the e.m.f. equation of a transformer is maximum value.
transformer
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1
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asked
Mar 19, 2018
by
anonymous
The function of breather in a transformer is?
Last answer:
The function of breather in a transformer is to arrest flow of moisture when outside air enters the transformer.
function
breather
transformer
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106
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1
answer
asked
Mar 19, 2018
by
anonymous
The path of magnetic flux in a transformer should have?
The path of magnetic flux in a transformer should have?
Last answer:
The path of magnetic flux in a transformer should have low reluctance.
magnetic
flux
transformer
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263
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1
answer
asked
Apr 5, 2018
by
anonymous
A large transformer operating at no load draws an exciting current Io of 5A, when the primary is connected to...
A large transformer operating at no load draws an exciting current Io of 5A, when the primary is connected to a 120 V, 60 Hz source. From a wattmeter test, it is known that iron losses are equal to 180 W. Calculate the reactive power absorbed by the core. (A) 600 var (B) 572 var (C) 180 var (D) 360 var
Last answer:
572var
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1
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asked
May 8, 2018
by
anonymous
The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be :
The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above
Last answer:
The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : 34.64 kVA
kva
rating
three-phase
transformer
voltage
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130
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1
answer
asked
Mar 19, 2018
by
anonymous
Which winding in a transformer has more number of turns ?
Last answer:
High voltage winding in a transformer has more number of turns.
transformer
turns
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asked
Mar 19, 2018
by
anonymous
In a transformer the tappings are generally provided on?
Last answer:
In a transformer, the tappings are generally provided on low voltage side.
transformer
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