Answer :
In an actual transformer the iron loss remains practically constant from no load to full load because core flux remains practically constant.
asked
Mar 19, 2018
by
anonymous
Answer :
If the supply frequency to the transformer is increased, the iron loss will increase.
asked
Mar 19, 2018
by
anonymous
Description : At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is : (A) 7000 W (B) 6000 W (C) 8000 W (D) 4000 W
Answer :
At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is : 6000 W
asked
Apr 30, 2018
by
anonymous
Description : Dielectric loss in a capacitor is best measured by (A) Wien Bridge (B) Schering Bridge (C) Anderson Bridge (D) Heaviside-Campbell Equal Ratio Bridge
Answer :
Dielectric loss in a capacitor is best measured by Schering Bridge
asked
Apr 25, 2018
by
anonymous
Description : When secondary of a current transformer is open-circuited its iron core will be?
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.
asked
Mar 19, 2018
by
anonymous
Description : A ferrite core has less eddy current loss than an iron core because?
Answer :
A ferrite core has less eddy current loss than an iron core because ferrites have high hysteresis.
asked
Mar 25, 2018
by
anonymous
Description : A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is
Answer :
A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is 0.707
asked
May 8, 2018
by
anonymous
Answer :
A direct current can be measured by a D.C. potentiometer in conjunction with a standard resistance.
asked
Mar 21, 2018
by
anonymous
Description : The self inductance of a coil can be measured using (A) Wien’s Bridge (B) Schering Bridge (C) Anderson’s Bridge (D) Wheatstone Bridge
Answer :
The self inductance of a coil can be measured using Anderson’s Bridge
asked
Apr 28, 2018
by
anonymous
Answer :
Resistances can be measured with the help of ohmmeters and resistance bridges.
asked
Mar 21, 2018
by
anonymous
Description : Corona loss in transmission lines can be reduced by (A) using small diameter conductors (B) using bundled conductors (C) using less spacing between conductors (D) increasing the transmission line voltage
Answer :
Corona loss in transmission lines can be reduced by using bundled conductors
asked
Apr 28, 2018
by
anonymous
Answer :
The full-load copper loss of a trans¬former is 1600 W. At half-load, the copper loss will be 400 W.
asked
Mar 19, 2018
by
anonymous
Answer :
A moving iron instrument can be used for both D.C. and A.C.
asked
Mar 21, 2018
by
anonymous
Description : How can power loss be reduced?
asked
Mar 10, 2018
by
anonymous
Description : Select insulating materials for following parts : (i) Insulation between heating element and base plate of electric iron. (ii) Insulation used over copper or aluminium conductor used for making coils. (iii) Transformer bushings. (iv) Insulation between transmission line and pole.
Answer :
Parts Insulating Materials Insulation between heating element and base plate of electric iron. Mica Insulation used over copper or aluminium conductor used for making coils. ... Transformer bushings Porcelain Insulation between transmission line and pole. Porcelain
asked
May 7, 2020
by
anonymous
Description : The power consumed by a balanced 3-ph load is measured by two-wattmeter method. The meter readings are 8 kW and 4 kW. The power factor of the load is (A) zero (B) 0.5 (C) between zero and 0.5 (D) between 0.5 and unity
Answer :
The power consumed by a balanced 3-ph load is measured by two-wattmeter method. The meter readings are 8 kW and 4 kW. The power factor of the load is between 0.5 and unity
asked
Apr 28, 2018
by
anonymous
Answer :
E.m.f. of a Weston cell is accurately measured by electrostatic voltmeter.
asked
Mar 21, 2018
by
anonymous
Answer :
The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.
asked
Mar 19, 2018
by
anonymous
Answer :
The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.
asked
Mar 19, 2018
by
anonymous
Description : The maximum load that a power transformer can carry is limited by its?
Answer :
The maximum load that a power transformer can carry is limited by its voltage ratio.
asked
Mar 19, 2018
by
anonymous
Description : In a circuit containing R, L and C, power loss can take place in?
Answer :
In a circuit containing R, L and C, power loss can take place in R only.
asked
Mar 25, 2018
by
anonymous
Description : Eddy current damping cannot be used for moving iron instrument because
Answer :
Eddy current damping cannot be used for moving iron instrument because the presence of a permanent magnet required for such purpose would affect the deflection and hence the reading of the instrument
asked
Apr 26, 2018
by
anonymous
Description : Why high voltage can reduce power loss?
Answer :
when voltage has increased due to reduced current flow, thus power loss given by ( I^2R) will be low due to reduced current(I^2) provided that resistance (R) is constant.
asked
Mar 10, 2018
by
anonymous
Description : The load of a consumer is generally measured in terms of : (A) Volts (B) Amperes (C) Ampere hour (D) kW
Answer :
The load of a consumer is generally measured in terms of : kW
asked
May 8, 2018
by
anonymous
Description : In a battery, the difference between the no-load voltage and the measured voltage output is called ________ A) Internal voltage B) Internal resistance C) External resistance D) All the above
Answer :
In a battery, the difference between the no-load voltage and the measured voltage output is called Internal resistance
asked
Apr 29, 2018
by
anonymous
Description : True value has been 50 whereas measured value is 40 then the percentage error in the reading will be ______. (A) 20% (B) 40% (C) 50% (D) 30%
Answer :
True value has been 50 whereas measured value is 40 then the percentage error in the reading will be 20%.
asked
May 8, 2018
by
anonymous
Description : Liquid flow rate is measured using (A) a pirani gauge (B) a pyrometer (C) an orifice plate (D) a bourdon tube
Answer :
Liquid flow rate is measured using an orifice plate
asked
Apr 26, 2018
by
anonymous
Answer :
If the current in a capacitor leads the voltage by 80°, the loss angle of the capacitor is 10°.
asked
Mar 21, 2018
by
anonymous
Answer :
A transformer can have regulation closer to zero on leading power factor.
asked
Mar 19, 2018
by
anonymous
Answer :
A transformer oil must be free from moisture.
asked
Mar 19, 2018
by
anonymous
Answer :
The main reason for generation of harmonics in a transformer could be saturation of core.
asked
Mar 19, 2018
by
anonymous
Description : In a transformer the resistance between its primary and secondary should be?
Answer :
In a transformer the resistance between its primary and secondary should be infinity.
asked
Mar 19, 2018
by
anonymous
Answer :
Iron losses in a D.C. machine are independent of variations in load.
asked
Mar 20, 2018
by
anonymous
Answer :
In a D.C. generator, the iron losses mainly take place in armature rotor.
asked
Mar 20, 2018
by
anonymous
Description : The dielectric strength of transformer oil is expected to be?
Answer :
The dielectric strength of transformer oil is expected to be 33 kV.
asked
Mar 19, 2018
by
anonymous
Answer :
The no load current in a transformer lags behind the applied voltage by an angle of about 75°.
asked
Mar 19, 2018
by
anonymous
Description : The noise produced by a transformer is termed as?
Answer :
The noise produced by a transformer is termed as hum.
asked
Mar 19, 2018
by
anonymous
Description : Which is the best conductor: silver, carbon, or iron?
Answer :
Silver is the best conductor. Carbon is the semiconductor. Iron have less conductance as compared to silver.
asked
Jul 1, 2019
by
anonymous
Description : An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be (1) unaffected (2) decreased (3) increased (4) either decreased or increased depending on the direction of the DC field
Answer :
An unshielded moving iron voltmeter is used to measure the voltage in an AC circuit. The stray DC magnetic field having a component along the axis will be either decreased or increased depending on the direction of the DC field
asked
Apr 29, 2018
by
anonymous
Description : The iron alloy, ALNICO is mainly used to make ________ A) Temporary magnets B) Permanent magnets C) Transmission lines D) None of these
Answer :
The iron alloy, ALNICO is mainly used to make Permanent magnets
asked
Apr 29, 2018
by
anonymous
Description : In DC motor iron losses are occurred in?
Answer :
In DC motor iron losses are occurred in the armature.
asked
Mar 26, 2018
by
anonymous
Description : In AC. circuits, laminated iron is invariably used in order to?
Answer :
In AC. circuits, laminated iron is invariably used in order to reduce eddy current loss.
asked
Mar 25, 2018
by
anonymous
Description : 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?
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.
Answer :
The transformer laminations are insulated from each other by thin coat of varnish.
asked
Mar 19, 2018
by
anonymous
Description : The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : (A) 256 W (B) 320 W (C) 500 W (D) 625 W
Answer :
The eddy current loss in a dc generator is 400 W at 40 Hz frequency of reversal and constant flux density. When frequency is increased to 50 Hz., eddy current loss is : 625 W
asked
Apr 30, 2018
by
anonymous
Description : In a magnetic material hysteresis loss takes place primarily due to?
Answer :
In a magnetic material hysteresis loss takes place primarily due to it high retentivity.
asked
Mar 25, 2018
by
anonymous
Description : In a loss-free R-L-C circuit the transient current is?
Answer :
In a loss-free R-L-C circuit the transient current is sinusoidal.
asked
Mar 25, 2018
by
anonymous
Answer :
In a D.C. machine stray loss is the sum of iron loss and mechanical loss.
asked
Mar 21, 2018
by
anonymous
Answer :
Corona is nothing but the ionization of surrounding air around the conductor which produces hissing noise,
asked
Aug 17, 2019
by
Fumo energy
Description : State the factors affecting hysteresis loss.
Answer :
i) Flux density ii) Frequency iii) Volume of the magnetic material iv) Nature of magnetic material
asked
Sep 4, 2018
by
anonymous