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

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

The magnitude of various voltage drops that occur in an alternator depends on?
Last Answer : The magnitude of various voltage drops that occur in an alternator depends on load current.
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594 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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176 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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316 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

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

What is meant by Power factor?
Last Answer : Ans. Power factor means ratio of true power to apparent power. It is cosine of phase angle between voltage and current. Its value is 1 for Unity P.F. Loads, 0 to 1 lagging for inductive loads and o to 1 leading for capacitive loads.
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17 views
1 answer

State the effects of low power factor on efficiency and voltage regulation of short transmission lines.
Last Answer : i) Effect of Low power factor on efficiency:- When power factor of load reduces current drawn by transmission line increases so copper losses in transmission line increases, hence transmission ... increases, so voltage drop in transmission line increases so regulation increases. (Become Poor)
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359 views
1 answer
asked
May 22, 2020
by
anonymous

Briefly explain how the power factor of an inductive circuit can be improved.
Last Answer : As we know that power factor should be corrected to ensure that the current supplied is cost friendly. Meaning the power factor should be around one but not greater than one(0.8-0.9) in a ... an inductive circuit due to the inductive reactance which oppose the change of current in the ac circuit.
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183 views
1 answer
asked
May 17, 2020
by
anonymous

What is the value of capacitance required to improve power factor from 0.7 to 0.9. Given that: Real power = 50 W Vrms of the source = 120 Frequency = 50 Hz #powerfactor
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197 views
0 answers
asked
May 17, 2020
by
anonymous

Why capacitors are used to improve power factor?
Last Answer : Capacitors generate reactive power instead of that drawn from source which is required by inductive loads.so it reduce the reactive current which is drawn from source to be drawn from capacitor.This control in Electric bills cost.
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183 views
3 answers
asked
Aug 18, 2019
by
anonymous

Discuss how power factor tariff results into energy conservation.
Last Answer : Power factor tariff results into energy conservation: i) Applying incentives and penalties according to power factor is an effective way, which enables consumer to improve power factor so that he can ... finally leads to reduction in the current drawn by the load and helps for energy conservation.
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2.6k views
1 answer
asked
Sep 29, 2018
by
anonymous

Draw and explain bulk correction method for power factor & control.
Last Answer : Bulk correction method for power factor & control: i) Here individual starter controls the capacitors located at distribution panel. ii) Centralized compensation is employed in large industrial plants where many ... capacitor units in steps to maintain P.F. more than preset limit (0.95).
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113 views
1 answer
asked
Sep 29, 2018
by
anonymous

State the incentives and penalties related with power factor tariff.
Last Answer : Incentives and penalties related with power factor tariff: In addition to basic tariff (Maximum Demand Tariff / KVA Maximum Demand Tariff / Load factor tariff) the tariff in which P.F. of ... industrial consumer/H.T/ commercial consumers with contract demand above 80 kw/ 100Kva/107 hp consumer.
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142 views
1 answer
asked
Sep 22, 2018
by
anonymous

With a neat sketch explain working of 1 phase dynamometer type power factor meter.
Last Answer : Working of 1 phase dynamometer type power factor meter : The current coil is connected in series with load. Two pressure coils marked as A and B are connected across the supply terminals ... becomes stationary and the pointer shows steady deflection corresponding to the power factor of the load.
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202 views
1 answer
asked
Sep 6, 2018
by
anonymous

State the significance of power factor.
Last Answer : Significance of power factor:- 1. Cosine of angle between voltage & current in a circuit is called power factor. 2. It is a measure of the real power in a circuit. 3. Inductive & ... KVA rating equipment 5. Greater conductor size 6. CosØ = R/Z CosØ= Active Power/ Apparent Power
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57 views
1 answer
asked
Sep 6, 2018
by
anonymous

A transformer has negative voltage regulation when its load power factor is (1) Zero (2) Unity (3) Leading (4) Lagging
Last Answer : 0
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5.1k views
3 answers
asked
Apr 30, 2018
by
anonymous

The power factor of dielectric : (A) is a function of temperature of the dielectric only (B) depends only on voltage stress to which the dielectric is stressed (C) always constant (D) both (A) and (B)
Last Answer : The power factor of dielectric : (A) is a function of temperature of the dielectric only (B) depends only on voltage stress to which the dielectric is stressed (C) always constant (D) both (A) and (B)
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167 views
1 answer
asked
Apr 30, 2018
by
anonymous

Power station having Load factor = 70%, capacity factor = 50%, used factor = 60%, maximum demand = 20MW then annual energy production is (1) 122.8 GWh (2) 198.55 GWh (3) 128.2 GWh (4) 188.82 GWh
Last Answer : Power station having Load factor = 70%, capacity factor = 50%, used factor = 60%, maximum demand = 20MW then annual energy production is 122.8 GWh
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148 views
1 answer
asked
Apr 29, 2018
by
anonymous
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In a synchronous generator delivering lagging power factor load (1) the excitation emf leads terminal voltage by the power angle (2) the excitation emf lags terminal voltage by the power angle (3) ... by the power factor angle (4) excitation emf lags the terminal voltage by the power factor angle
Last Answer : In a synchronous generator delivering lagging power factor load the excitation emf leads terminal voltage by the power angle
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340 views
1 answer
asked
Apr 29, 2018
by
anonymous

What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these
Last Answer : What is the power factor when a single phase watt meter operating on 200 V and 5 A for 5 hours makes 2016 revolutions and the meter constant in revolution is 420? A) 0.04 B) 1.04 C) 0.96 D) None of these
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209 views
1 answer
asked
Apr 29, 2018
by
anonymous

The benefit of power factor correction in a power system is (A) lower power consumption (B) increased demand charge (C) reduced load carrying capabilities in existing lines (D) reduced voltage profile
Last Answer : The benefit of power factor correction in a power system is lower power consumption
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104 views
1 answer
asked
Apr 28, 2018
by
anonymous

The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu from a lagging load are 45o and 15o, respectively. The direct axis and quadrature axis currents, respectively, are (A) 0.5 pu ... pu, 0.5 pu (C) 0.707 pu, 0.707 pu (D) 0.5 pu, 0.5 pu
Last Answer : The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu from a lagging load are 45o and 15o, respectively. The direct axis and quadrature axis currents, respectively, are 0.866 pu, 0.5 pu
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98 views
1 answer
asked
Apr 28, 2018
by
anonymous

The power factor of a D.C. circuit is always?
Last Answer : The power factor of a D.C. circuit is always unity.
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219 views
1 answer
asked
Mar 25, 2018
by
anonymous

The ratio of active power to apparent power is known as____ factor.
Last Answer : The ratio of active power to apparent power is known as power factor.
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927 views
1 answer
asked
Mar 25, 2018
by
anonymous

The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is?
Last Answer : The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is 32 kW.
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467 views
1 answer
asked
Mar 25, 2018
by
anonymous

Power factor of electric bulb is?
Last Answer : Power factor of electric bulb is unity.
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93 views
1 answer
asked
Mar 25, 2018
by
anonymous

The power factor at resonance in R-L- C parallel circuit is?
Last Answer : since a rlc circuit at resonance behaves like a pure resistive circuit, i.e there is no phase difference between current and voltage, hence the power factor is unity.
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975 views
2 answers
asked
Mar 25, 2018
by
anonymous

Power factor of the system is kept high?
Last Answer : Power factor of the system is kept high to reduce line losses, to maximise the utilization of the capacities of generators, lines and transformers, to reduce voltage regulation of the line.
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144 views
1 answer
asked
Mar 25, 2018
by
anonymous

Power factor of an inductive circuit is usually improved by connecting capacitor to it in?
Last Answer : Power factor of an inductive circuit is usually improved by connecting capacitor to it in parallel.
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278 views
1 answer
asked
Mar 25, 2018
by
anonymous

Capacitors for power factor correction are rated in?
Last Answer : Capacitors for power factor correction are rated in kVAR.
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84 views
1 answer
asked
Mar 25, 2018
by
anonymous

Poor power factor?
Last Answer : Poor power factor reduces load handling capability of electrical system, results in more power losses in the electrical system, overloads alternators, transformers and distribution lines, results in more voltage drop in the line.
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66 views
1 answer
asked
Mar 25, 2018
by
anonymous

Power factor of an electrical circuit is equal to?
Last Answer : Power factor of an electrical circuit is equal to R/Z, cosine of phase angle difference between current and voltage, kW/kVA.
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518 views
1 answer
asked
Mar 24, 2018
by
anonymous

Last Answer : The power factor of a single phase load can be calculated if the instruments available are three ammeters or three voltmeters.
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296 views
2 answers
asked
Mar 21, 2018
by
anonymous

Last Answer : In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at 120°.
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132 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a single phase power factor meter the phase difference between the currents in the two pressure coils is exactly 90°.
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352 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : The two pressure coils of a single phase power factor meter have the same dimensions and the same number of turns.
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158 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : A power factor meter has one current circuit and two pressure circuits.
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68 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : In a low power factor wattmeter the compensating coil is connected in series with pressure coil.
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489 views
1 answer
asked
Mar 21, 2018
by
anonymous
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Last Answer : In a low power factor wattmeter the pressure coil is connected to the load side of the current coil.
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375 views
1 answer
asked
Mar 21, 2018
by
anonymous

Last Answer : When a D.C. series motor is connected to A.C. supply, the power factor will be low because of high inductance of field and armature circuits.
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119 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The power factor of a single-phase induction motor is usually lagging.
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191 views
1 answer
asked
Mar 20, 2018
by
anonymous

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
Last Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.
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169 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The standard full-load power factor ratings for synchronous motors are unity or 0.8 leading.
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98 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.
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110 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : An induction motor has relatively high power factor at near full load.
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92 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a distribution system, in order to improve power factor, the synchronous capacitors are installed at the receiving end.
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185 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : For a consumer the most economical power factor is generally 0.95 lagging .
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209 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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115 views
1 answer
asked
Mar 20, 2018
by
anonymous
