In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?
Last Answer : In an alternator, at lagging power factor the generated voltage per phase as compared to that at unity power factor must be more than terminal voltage.
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524 views
1 answer
asked
Mar 18, 2018
by
anonymous
In alternator where the voltage drop occurs?
Last Answer : In alternator voltage drop occurs in armature resistance, leakage reactance, and armature reactance.
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139 views
1 answer
asked
Mar 18, 2018
by
anonymous
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The power factor of an alternator depends on?
Last Answer : The power factor of an alternator depends on load.
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116 views
1 answer
asked
Mar 18, 2018
by
anonymous
State working principle of alternator. State the meaning self and separate excitation.
Last Answer : Working principle of alternator: When a conductor is moved in magnetic field or a magnetic field moved with respect to conductor, according to Faraday's law of electromagnetic induction, the conductor ... like battery or shaft-mounted exciter, then the excitation is said to be separate excitation.
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175 views
1 answer
asked
May 27, 2020
by
anonymous
Explain the construction of alternator with neat diagram.
Last Answer : Diagram: Construction of three phase alternator: Construction wise, an alternator generally consists of field poles placed on the rotating fixture of the machine i.e. rotor as shown in the ... of rotor used in construction of alternator, 1. Salient pole type. 2. Cylindrical rotor type.
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306 views
1 answer
asked
Jul 30, 2019
by
anonymous
Is the speed of alternator is directly proportional to frequency?
Last Answer : Yes, speed of alternator is directly proportional to frequency.
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126 views
1 answer
asked
Mar 18, 2018
by
anonymous
At which power factor alternator is said to be overexcited?
Last Answer : At leading power factor alternator is said to be overexcited.
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97 views
1 answer
asked
Mar 18, 2018
by
anonymous
Define armature reaction in an alternator. Explain the effect of armature reaction at various P.F. of loads of alternator.
Last Answer : Armature Reaction: The effect of armature flux on main flux is called as armature reaction. Armature Reaction at Various Power Factors: When armature is loaded, the armature flux modifies ... lagging p.f. For capacitive loads the effect of flux is partly distorting and partly strengthening.
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421 views
1 answer
asked
May 7, 2020
by
anonymous
What is the Laplace transform of step signal of 5 units magnitude? A) 5s B) 5/s C) s/5 D) 1/s
Last Answer : What is the Laplace transform of step signal of 5 units magnitude? A) 5s B) 5/s C) s/5 D) 1/s
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251 views
1 answer
asked
Jun 18, 2018
by
anonymous
In a Bode magnitude plot, which one of the following slopes would be exhibited at high frequencies by a 4th order all-pole system? (A) – 80 dB/decade (B) – 40 dB/decade (C) +40 dB/decade (D) +80 dB/decade
Last Answer : In a Bode magnitude plot, which one of the following slopes would be exhibited at high frequencies by a 4th order all-pole system? (A) – 80 dB/decade (B) – 40 dB/decade (C) +40 dB/decade (D) +80 dB/decade
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1.0k views
1 answer
asked
Apr 26, 2018
by
anonymous
In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of?
Last Answer : In R-L-C series resonant circuit magnitude of resonance frequency can be changed by changing the value of L or C.
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1.2k views
1 answer
asked
Mar 25, 2018
by
anonymous
Magnitude of current at resonance in R-L-C circuit?
Last Answer : The current will be maximum if it is a series rlc circuit.
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282 views
2 answers
asked
Mar 25, 2018
by
anonymous
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If two equal forces of magnitude P act at an angle 9°, their resultant will be
Last Answer : If two equal forces of magnitude P act at an angle 9°, their resultant will be IP cos 9/2.
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379 views
1 answer
asked
Mar 22, 2018
by
anonymous
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What is an alternator?
Last Answer : Ans. Alternator is a machine which converts mechanical energy into electrical energy
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5 views
1 answer
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Draw equivalent circuit of alternator.
Last Answer : Equivalent circuit of alternator
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254 views
1 answer
asked
May 6, 2020
by
anonymous
Alternator
Last Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }
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63 views
1 answer
asked
Jul 6, 2019
by
anonymous
What is the frequency of an alternator which has 2 poles and makes 3600 revolutions per minute? A) 3600 HZ B) 60 Hz C) 120 Hz D) None of these
Last Answer : What is the frequency of an alternator which has 2 poles and makes 3600 revolutions per minute? A) 3600 HZ B) 60 Hz C) 120 Hz D) None of these
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2.6k views
1 answer
asked
Apr 29, 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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430 views
1 answer
asked
Apr 28, 2018
by
anonymous
The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is (A) 2/3 (B) 5/6 (C) 7/8 (D) 6/7
Last Answer : The fractional-pitch used for eliminating 7th harmonic from the emf wave of an alternator is 6/7
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493 views
1 answer
asked
Apr 28, 2018
by
anonymous
Last Answer : An alternator coupled to a hydraulic turbine runs at slow speed, as compared to others.
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105 views
1 answer
asked
Mar 20, 2018
by
anonymous
What causes diodes to fail in alternator?
Last Answer : alternator
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77 views
1 answer
asked
Mar 15, 2018
by
anonymous
When an alternator connected to the bus-bar is shut down the bus-bar voltage will (a) fall (b) rise (c) remain unchanged (d) none of the above
Last Answer : (c) remain unchanged
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18 views
1 answer
The voltage gain of a common -source JFET amplifier depends up on its (1) Input impedance (2) Amplification factor (3) Dynamic drain resistance (4) Drain load resistance
Last Answer : B
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990 views
3 answers
asked
Apr 30, 2018
by
anonymous
Last Answer : The voltage gain of triode depends on plate voltage.
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102 views
1 answer
asked
Mar 26, 2018
by
anonymous
An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: A) 1000 rpm B) 920 rpm C) 950 rpm D) 970 rpm
Last Answer : An 8-pole alternator runs at 750 rpm and supplies power to a 6-pole induction motor which has a full load slip of 3 percent. The full load speed of the induction motor will be: 970 rpm
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1.3k views
1 answer
asked
Jun 4, 2018
by
anonymous
In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50
Last Answer : In an alternator if the winding is short pitched by 60 electrical degrees, its pitch factor will be: A) 1.0 B) 0.866 C) 0.75 D) 0.50
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6.1k views
1 answer
asked
Jun 4, 2018
by
anonymous
The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will: A) ... as a synchronous motor but will rotate in a reverse direction to that corresponding to generator action
Last Answer : The driving power from the prime-mover driving the alternator is lost but the alternator remains connected to the supply network; the field supply also remains on. The alternator will: behave as a synchronous motor and will rotate in the same direction
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178 views
1 answer
asked
Jun 4, 2018
by
anonymous
Which alternator will have more number of poles ? (a) coupled to steam turbine (b) coupled to gas turbine (c) coupled to hydraulic turbine (d) None of the above
Last Answer : b
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276 views
2 answers
asked
May 26, 2018
by
anonymous
If the excitation of an alternator operating in parallel with other alternators decreased, its: (1) Power factor becomes more leading (2) Output Kw will change (3) Power factor becomes more lagging (4) Power factor becomes unity
Last Answer : If the excitation of an alternator operating in parallel with other alternators decreased, its: Power factor becomes more leading
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360 views
1 answer
asked
May 22, 2018
by
anonymous
Drop in alternator frequency is corrected by: (1) Damper winding (2) Increased prime mover output (3) Automatic voltage regulator (4) None of these
Last Answer : Drop in alternator frequency is corrected by: Increased prime mover output
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2.4k views
1 answer
asked
May 22, 2018
by
anonymous
A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a terminal voltage of 2000 V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200 A is (A) 1 V (B) 10 V (C) 100 V (D) 1000 V
Last Answer : 800
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2.8k views
2 answers
asked
May 17, 2018
by
anonymous
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A 8 pole alternator rotates at 750 r.p.m. Its frequency is
Last Answer : A 8 pole alternator rotates at 750 r.p.m. Its frequency is 50 Hz
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1.1k views
1 answer
asked
May 15, 2018
by
anonymous
A 60 Hz, 2 pole alternator should run at • a. 3000 r.p.m. c. 1500 r.p.m. • b. 3600 r.p.m. d. 1800 r.p.m.
Last Answer : A 60 Hz, 2 pole alternator should run at 3600 r.p.m.
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160 views
1 answer
asked
May 14, 2018
by
anonymous
Which of the following faults is most likely to occur in cables ? (a) Cross or short-circuit fault (b) Open circuit fault (c) Breakdown of cable insulation (d) All of the above
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2 views
0 answers
Why does surge impedance loading (SIL) increase with increase in voltage level?
Last Answer : Answer: SIL varies as the square of the operating voltage, so SIL increases with increase in voltage level
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24 views
1 answer
Electro-mechanical voltage regulators are generally used in (a) reactors (b) generators (c) transformers (d) all of the above
Last Answer : (b) generators
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11 views
1 answer
The frequency of voltage generated, in case of generators, can be increased by (a) using reactors (b) increasing the load (c) adjusting the governor (d) reducing the terminal voltage (e) none of the above
Last Answer : (c) adjusting the governor
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10 views
1 answer
When the interconnector between two stations has large reactance (a) the transfer of power will take place with voltage fluctuation and noise (b) the transfer of power will take place with least loss ... out of step be¬cause of large angular displacement between the stations (d) none of the above
Last Answer : (c) the stations will fall out of step be¬cause of large angular displacement between the stations
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14 views
1 answer
For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV
Last Answer : (a) 150 to 220 kV
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40 views
1 answer
Constant voltage transmission entails the following disadvantage (a) large conductor area is required for same power transmission (b) short-circuit current of the system is increased (c) either of the above (d) none of the above
Last Answer : (b) short-circuit current of the system is increased
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12 views
1 answer
In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above
Last Answer : (b) secondary winding
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50 views
1 answer
Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical ? (a) Static condenser (b) Synchronous condenser (c) Tap changing transformer (d) Booster transformer
Last Answer : (d) Booster transformer
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19 views
1 answer
For transmission of power over a distance of 200 km, the transmission voltage should be (a) 132 kV (b) 66 kV (c) 33 kV (d) 11 kV
Last Answer : (a) 132 kV
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53 views
1 answer
The voltage drop, for constant voltage transmission is compensated by installing (a) inductors (b) capacitors (c) synchronous motors (d) all of above (e) none of the above
Last Answer : (c) synchronous motors
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11 views
1 answer
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By which of the following a bus-bar is rated ? (a) Current only (b) Current and voltage (c) Current, voltage and frequency (d) Current, voltage, frequency and short time current
Last Answer : (d) Current, voltage, frequency and short time current
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16 views
1 answer
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Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km
Last Answer : (a) 20—25 km
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15 views
1 answer
The power transmitted will be maximum when (a) corona losses are minimum (b) reactance is high (c) sending end voltage is more (d) receiving end voltage is more
Last Answer : (c) sending end voltage is more
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30 views
1 answer
Which of the following is usually not the generating voltage ? (a) 6.6 kV (b) 8.8 kV (c) 11 kV (d) 13.2 kV
Last Answer : (b) 8.8 kV
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33 views
1 answer
As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only (a) 31.25 percent of copper (b) 33.3 percent of copper (c) 66.7 percent of copper (d) 125 percent of copper
Last Answer : (a) 31.25 percent of copper
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18 views
1 answer
Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is (a) 25 percent (b) 50 percent (c) 75 percent (d) 100 percent
Last Answer : (b) 50 percent
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33 views
1 answer
