Description : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
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.
asked
Mar 20, 2018
by
anonymous
Description : At which time power factor of the induction motor is low?
Answer :
The power factor of the inducction motor is low at the time of starting as compare to while the induction motor is running.
asked
Mar 3, 2018
by
anonymous
Answer :
The power factor of a single-phase induction motor is usually lagging.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Description : Why does induction motor have high starting current?
Answer :
In induction motor , the flux produce is quadrature to the applied voltage. Since when we are going to start motor , there is no flux present inside . So in order to lets say compensate it ... times of current to further increase flux. So that is reason for high starting current in induction motor
asked
Mar 15, 2018
by
anonymous
Description : Power factor of the system is kept high?
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.
asked
Mar 25, 2018
by
anonymous
Description : What is the advantage of high power factor?
Answer :
Reduced copper losses Smaller conductor size Improve voltage regulation Increase system capability Less energy bill
asked
Mar 10, 2018
by
anonymous
Description : Explain energy conservation technique “by improving power quality” for induction motor.
Answer :
Energy conservation method in induction motor by improving power quality: Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage unbalance, maintaining ... losses can be minimized by using harmonic filter thus reducing the harmonics in the system.
asked
Sep 22, 2018
by
anonymous
Answer :
High load factor indicates total plant capacity is utilised for most of the time.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Description : If the load of the normally excited synchronous motor is increased the power factor will?
Answer :
If the load of the normally excited synchronous motor is increased the power factor will become lagging.
asked
Mar 18, 2018
by
anonymous
Description : The synchronous motor which works on leading power factor and does not drive any mechanical load is called?
Answer :
The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.
asked
Mar 18, 2018
by
anonymous
Description : If the field of synchronous motor is under excited, power factor will be?
Answer :
If the field of synchronous motor is under excited, power factor will be lagging.
asked
Mar 18, 2018
by
anonymous
Description : How can we improve power factor using synchronous motor?
asked
Mar 15, 2018
by
anonymous
Answer :
Yes, we can make the power factor of synchronous motor leading by adjusting its excitation.
asked
Mar 6, 2018
by
anonymous
Description : An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is (A) 5.06 kW (B) 0.3 kW (C) 100 kW (D) 83.33 kW
Answer :
An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is 83.33 kW
asked
Apr 28, 2018
by
anonymous
Description : The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?
Answer :
Ns equals f/pair pole 50/4 - 12.5
asked
Dec 31, 2017
by
anonymous
Description : In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is (A) 0.2 Ω (B) 0.3 Ω (C) 0.4 Ω (D) 0.5 Ω
Answer :
In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is 0.3 Ω
asked
Apr 28, 2018
by
anonymous
Description : Why a dc series motor has a high starting torque?
asked
Mar 15, 2018
by
anonymous
Answer :
In a distribution system, in order to improve power factor, the synchronous capacitors are installed at the receiving end.
asked
Mar 20, 2018
by
anonymous
Answer :
For a consumer the most economical power factor is generally 0.95 lagging .
asked
Mar 20, 2018
by
anonymous
Answer :
The primary reason for low power factor is supply system is due to installation of induction motors.
asked
Mar 20, 2018
by
anonymous
Answer :
Power plant having maximum demand more than the installed rated capacity will have utilisation factor more than unity.
asked
Mar 20, 2018
by
anonymous
Answer :
Load factor of a power station is generally less than unity.
asked
Mar 20, 2018
by
anonymous
Answer :
Load factor of a power station is defined as average load/maximum demand.
asked
Mar 20, 2018
by
anonymous
Description : Can a synchronous condenser improve power factor?
Answer :
Yes, synchronous condenser can improve power factor.
asked
Mar 19, 2018
by
anonymous
Description : What is the maximum value of power factor?
Answer :
1 is the maximum value of power factor.
asked
Mar 19, 2018
by
anonymous
Description : In an alternator at lagging power factor the generated voltage per phase as compared to that at unity power factor?
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.
asked
Mar 18, 2018
by
anonymous
Answer :
Capacitor start motor has high torque in starting
asked
Sep 13, 2017
by
anonymous
Description : What will happen if the induction motor runs at synchronous speed ?
Answer :
Since there is always slip present in rotor it cannot run at synchronous speed no current will be developed hence no torque will developed
asked
Aug 18, 2019
by
anonymous
Description : The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is
Answer :
The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is 4 percent
asked
Apr 29, 2018
by
anonymous
Description : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for
Answer :
A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles
asked
Apr 29, 2018
by
anonymous
Description : A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60
Answer :
0
asked
Apr 28, 2018
by
anonymous
Description : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down
Answer :
The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque
asked
Apr 28, 2018
by
anonymous
Description : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?
Answer :
The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be 4.
asked
Mar 26, 2018
by
anonymous
Description : A change of 4% in the supply voltage to an induction motor will produce a change of approximately
Answer :
A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque
asked
May 8, 2018
by
anonymous
Description : In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will (1) reduce to one-half (2) reduce to one-fourth (3) remain unchanged (4) increase four times
Answer :
In an induction motor if the flux density is reduced.to one-half, of its normal value then the torque will reduce to one-fourth
asked
May 1, 2018
by
anonymous
Answer :
The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it helps in reducing the tendency of the rotor teeth to remain under the stator teeth.
asked
Mar 20, 2018
by
anonymous
Description : Why starter is required for starting an induction motor?
asked
Mar 15, 2018
by
anonymous
Description : A transformer has negative voltage regulation when its load power factor is (1) Zero (2) Unity (3) Leading (4) Lagging
Answer :
Leading
asked
Apr 30, 2018
by
anonymous
Answer :
A power factor meter has one current circuit and two pressure circuits.
asked
Mar 21, 2018
by
anonymous
Description : What can cause high amperage on a motor?
Answer :
High amperage can result in a motor when the amount of load increases. when load increases , it reduces the rotor speed which increases the slip at constant synchronous speed ... , as a result more current shall have been drawn to maintain the additional load.
asked
Mar 15, 2018
by
anonymous
Description : The power factor at resonance in R-L- C parallel circuit is?
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.
asked
Mar 25, 2018
by
anonymous
Answer :
In a dynamometer 3-phase power factor meter, the planes of the two moving coils are at 120°.
asked
Mar 21, 2018
by
anonymous
Answer :
For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.
asked
Mar 20, 2018
by
anonymous
Description : At which power factor alternator is said to be overexcited?
Answer :
At leading power factor alternator is said to be overexcited.
asked
Mar 18, 2018
by
anonymous
Description : Briefly explain how the power factor of an inductive circuit can be improved.
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.
asked
May 17, 2020
by
anonymous
Description : The input of an A.C. circuit having power factor of 0.8 lagging is 40 kVA The power drawn by the circuit is?
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.
asked
Mar 25, 2018
by
anonymous
Description : Power factor of an inductive circuit is usually improved by connecting capacitor to it in?
Answer :
Power factor of an inductive circuit is usually improved by connecting capacitor to it in parallel.
asked
Mar 25, 2018
by
anonymous
Description : Power factor of an electrical circuit is equal to?
Answer :
Power factor of an electrical circuit is equal to R/Z, cosine of phase angle difference between current and voltage, kW/kVA.
asked
Mar 24, 2018
by
anonymous