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
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261 views
1 answer
asked
Jun 18, 2018
by
anonymous

Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is
Last Answer : Total instantaneous power supplied by a 3-phase ac supply to a balanced R-L load is constant
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1.3k views
1 answer
asked
Apr 28, 2018
by
anonymous

Draw the waveform of three phase AC supply voltage.
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215 views
0 answers
asked
Aug 11, 2018
by
anonymous

The SCR would be turned OFF by voltage reversal of applied anode-cathode ac supply frequency of A) 10 kHz B) 10 Hz C) 5 kHz D) 5 Hz
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187 views
0 answers
asked
Jun 18, 2018
by
anonymous

What will happen if the primary of a transformer is connected to D.C. supply? (A) Transformer will operate with low efficiency (B) Transformer will operate with high efficiency (C) No effect (D) Transformer may start to smoke and burn
Last Answer : What will happen if the primary of a transformer is connected to D.C. supply? (A) Transformer will operate with low efficiency (B) Transformer will operate with high efficiency (C) No effect (D) Transformer may start to smoke and burn
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551 views
1 answer
asked
May 8, 2018
by
anonymous

Last Answer : If the supply frequency to the transformer is increased, the iron loss will increase.
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170 views
1 answer
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?
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.
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158 views
1 answer
asked
Mar 19, 2018
by
anonymous

Last Answer : If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.
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92 views
1 answer
asked
Mar 20, 2018
by
anonymous

To measure an A. C. voltage by using an A.C. potentiometer, it is desirable that the supply for the potentiometer in taken?
Last Answer : To measure an A. C. voltage by using an A.C. potentiometer, it is desirable that the supply for the potentiometer in taken from the same source as the unknown voltage.
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224 views
1 answer
asked
Mar 21, 2018
by
anonymous

Can transformer convert AC to DC?
Last Answer : No, Transformer cannot convert AC to DC.
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3.0k views
9 answers
asked
Dec 9, 2017
by
anonymous

The instructions for starting the computer are house on a. Random access memory b. CD-Rom c. Read only memory chip d. All of above
Last Answer : c. Read only memory chip
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22 views
1 answer
asked
Aug 4, 2021
by
anonymous

Last Answer : Igbt alone cant convert dc to ac. igbt half bridge or full bridge or three phase topology could be used to convert dc to ac. also igbt gates should be driven by microcontroller or pwm/spwm gate driving signals ... e4(-) and g4 c2e1 and c4e3 pins are AC output pins. its name is igbt inverter.
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187 views
1 answer
asked
Feb 24, 2018
by
Amit Sharma

Last Answer : The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a two-phase winding.
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176 views
1 answer
asked
Mar 21, 2018
by
anonymous

State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.
Last Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows: 1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine
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387 views
1 answer
asked
May 7, 2020
by
anonymous

What is need of regulated power supply?
Last Answer : A regulated power supply is used to ensure that the output remains constant even if the input changes. But sometimes main supply voltage, load, and surrounding temperature keep changing and altering the ... power supply is needed that will accept an AC input and give a constant DC output.
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139 views
3 answers
asked
Sep 4, 2018
by
anonymous

Two 100W, 200V lamps are connected in series across a 200V supply. The total power consumed by each lamp will be in Watts
Last Answer : 4800
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453 views
2 answers
asked
May 8, 2018
by
anonymous

We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be
Last Answer : We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be 2.4 kOhm
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151 views
1 answer
asked
May 8, 2018
by
anonymous

Consider a circuit with three parallel branches connected across a DC supply. What is the ratio of the branch currents I1 : I2 : I3 if the branch resistances are in the ratio of 2 : 3 : 4 respectively? A) 2 : 3 : 4 B) 6 : 4 : 3 C) 4 : 3 : 2 D) None of these
Last Answer : Consider a circuit with three parallel branches connected across a DC supply. What is the ratio of the branch currents I1 : I2 : I3 if the branch resistances are in the ratio of 2 : 3 : 4 respectively? A) 2 : 3 : 4 B) 6 : 4 : 3 C) 4 : 3 : 2 D) None of these
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216 views
1 answer
asked
Apr 29, 2018
by
anonymous

In a three-phase supply floating neutral is undesirable because it way give rise to?
Last Answer : In a three-phase supply floating neutral is undesirable because it way give rise to unequal line voltages across the load.
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117 views
1 answer
asked
Mar 25, 2018
by
anonymous

The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of?
Last Answer : The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of iron loss in core.
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171 views
1 answer
asked
Mar 25, 2018
by
anonymous

Last Answer : Reason is kinetic energy
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290 views
2 answers
asked
Mar 20, 2018
by
anonymous

How To Make An Emergency Supply Kit
Last Answer : How To Make An Emergency Supply Kit Accidents and natural disasters happen; they are among the unavoidable and unpleasant occurrences that happen in life. Unfortunately, we can't predict when and ... emergency supply kit properly, and you'll be able to make it through the catastrophe unscathed.
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7 views
1 answer
asked
May 14, 2021
by
anonymous

Analyze the effect of supply voltage on performance of LED as regards current, Lumen output, efficacy and life.
Last Answer : 1) Effect on Current:- In LED current depends upon supply voltage, if voltage get changes then current also change but this change in current will be control by resistors which are connected in series. 2) ... 4) Effect on Life:- If supply voltage is not stable then life of LED get reduced.
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107 views
1 answer
asked
May 3, 2020
by
anonymous
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Draw the block diagram of regulated power supply, explain function of each block and draw waveforms of each stage.
Last Answer : 1. A step down transformer 2. A rectifier 3. A filter 4. A regulator Operation of Regulated Power Supply:- Step Down Transformer:- A step down transformer will ... regulator. A regulator will maintain the output constant even when changes at the input or any other changes occur.
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2.0k views
3 answers
asked
May 2, 2020
by
anonymous

Define phase sequence of three phase supply with waveforms. What is normal phase sequence? Which 3 standard colours are used to denote the phase sequence?
Last Answer : It is sunnosoidal sequence.
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135 views
1 answer
asked
Aug 11, 2018
by
anonymous

Define balanced supply and unbalanced supply.
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138 views
0 answers
asked
Aug 11, 2018
by
anonymous

What is the Power Supply specification for 8085AH microprocessor? A) Single +5V supply with 10% voltage margins B) Dual +5V supply with 10% voltage margins C) Single +10V supply with 5% voltage margins D) Dual +5V supply with 5% voltage margins
Last Answer : What is the Power Supply specification for 8085AH microprocessor? A) Single +5V supply with 10% voltage margins B) Dual +5V supply with 10% voltage margins C) Single +10V supply with 5% voltage margins D) Dual +5V supply with 5% voltage margins
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260 views
1 answer
asked
Jun 18, 2018
by
anonymous

A change of 4% in the supply voltage to an induction motor will produce a change of approximately
Last Answer : A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque
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491 views
1 answer
asked
May 8, 2018
by
anonymous

The supply for arc welding is :
Last Answer : The supply for arc welding is : Low voltage, high current ac or dc voltage
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93 views
1 answer
asked
Apr 29, 2018
by
anonymous

The time period of third harmonic of power supply frequency, in milliseconds, is (A) 20 (B) 3.33 (C) 6.66 (D) 60
Last Answer : The time period of third harmonic of power supply frequency, in milliseconds, is 6.66
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541 views
1 answer
asked
Apr 28, 2018
by
anonymous

While keeping the excitation constant, if the steam supply of an alternator running in parallel with another identical alternator is increased, then (A) It would over-run the other alternator (B) Its rotor ... (C) Its portion of share in load will increase (D) Its power factor would be decreased.
Last Answer : While keeping the excitation constant, if the steam supply of an alternator running in parallel with another identical alternator is increased, then Its portion of share in load will increase
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433 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : Overhead lines for power supply to tramcars are at a minimum height of 10 m.
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2.6k views
1 answer
asked
Mar 22, 2018
by
anonymous

A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will?
Last Answer : A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will not start at all.
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235 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then the stator current will be zero.
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119 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The primary reason for low power factor is supply system is due to installation of induction motors.
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116 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : For high value of diversity factor, a power station of given installed capacity will be in a position to supply more number of consumers.
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174 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Rectifier is use in power supply to convert Alternating current (AC) to Direct Current (DC) .
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109 views
1 answer
asked
Sep 13, 2017
by
anonymous

52 A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be A. 1600 B. 250 C. 400 D. 1250
Last Answer : A. 1600
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8 views
1 answer

why transformer don't work on DC supply?
Last Answer : A DC current does not produce a changing magnetic field which is capable of inducing current on the secondary windings of a transformer through mutual induction process.
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131 views
2 answers
asked
Dec 9, 2017
by
anonymous

What is the advantage of AC over DC electrical transmission?
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82 views
0 answers
asked
Apr 26, 2020
by
anonymous

Alternating current (AC)
Last Answer : AC stands for Alternating Current meaning voltage or current that changes polarity or direction respectively over time. An Alternating Current (AC) is an electric current whose magnitude ... energy are known as alternators and are simpler construction than DC electromechanical generators.
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185 views
2 answers
asked
Nov 22, 2019
by
anonymous

Why are DC motors used in trains and not AC motors ?
Last Answer : The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.
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164 views
1 answer
asked
Sep 3, 2019
by
anonymous

Why is AC considered more efficient than DC?
Last Answer : Ac is more efficient than dc because it is easy to maintain and change the voltage of ac for transmission and distribution purpose. Plant cost of ac transmission is much lower compared to dc transmission. When fault occurs it is easy to interrupt ac supply.
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100 views
1 answer
asked
Aug 28, 2019
by
anonymous

Which is more dangerous AC or DC and why ?
Last Answer : Dc is more dangerous than Ac because in Ac the voltage will varies but in dc the constant voltage
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152 views
2 answers
asked
Aug 28, 2019
by
anonymous

Why is AC better for long distance power transmission than DC ?
Last Answer : ac is more economical to transmit for long distances . wires can be made smaller by step up transformer .. since major cost are wires to transmit .. then at the end of distance step down transformer is used for commercial use.
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211 views
4 answers
asked
Aug 25, 2019
by
anonymous

Why can't we store AC in batteries instead of DC ?
Last Answer : Because the direction of the current changes in AC electricity, you cannot directly store the power. Placing a capacitor in an AC circuit has no effect on the alternating flow of the electricity. The only ... is indirectly, by storing DC and then using a power inverter to convert the DC to AC.
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116 views
3 answers
asked
Aug 19, 2019
by
anonymous

What is the conversion between. AC to AC ? DC to DC? AC to DC? DC to AC ?
Last Answer : 1.ac to ac is regulation 2.dc to dc is chopper 3.ac to dc is rectifier 4.dc to ac is inverter
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101 views
1 answer
asked
Aug 15, 2019
by
anonymous

AC generator
Last Answer : A.C power can be generated as a single phase or as a balanced poly-phase system. However, it was found that 3-phase power generation at 50 Hz will be economical and most suitable. Present day three phase generators ... has uniform air gap (figure 2.1(b)) and used when speed is high.
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2.4k views
1 answer
asked
Aug 8, 2019
by
anonymous

Define : i) Average value ii) RMS value of an AC Wave.
Last Answer : i) Average value: The average value is defined as the average of all instantaneous values during one alternation . That is, the ratio of the sum of all considered instantaneous values to the ... as produced by the alternating current when flowing through the same resistance for the same time.
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402 views
1 answer
asked
Jul 30, 2019
by
anonymous

Is the power line voltage available in our homes a dc or an ac voltage?
Last Answer : The power line voltage available in our homes is AC. Mobile dwellings are the most commonly DC-supplied homes and even then they tend to include AC supply for heavier loads.
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5.2k views
1 answer
asked
Jun 29, 2019
by
anonymous
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