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 : 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 : The synchronous motor will develop maximum power when the load angle is?
Answer :
The synchronous motor will develop maximum power when the load angle is 900.
asked
Mar 18, 2018
by
anonymous
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 : 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) excitation emf leads the terminal voltage by the power factor angle (4) excitation emf lags the terminal voltage by the power factor angle
Answer :
In a synchronous generator delivering lagging power factor load the excitation emf leads terminal voltage by the power angle
asked
Apr 29, 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 : If we change the excitation of synchronous machine will it affect on power factor?
Answer :
Yes, If we change the excitation of synchronous machine it will affect on power factor. If the synchronous motor is overexcited then it will have leading power factor and if the motor is underexcited then it will have lagging power factor.
asked
Mar 18, 2018
by
anonymous
Answer :
As the load is increased the speed of D.C. shunt motor will reduce slightly.
asked
Mar 20, 2018
by
anonymous
Answer :
The standard full-load power factor ratings for synchronous motors are unity or 0.8 leading.
asked
Mar 20, 2018
by
anonymous
Answer :
An over excited synchronous motor on noload is known as synchronous condenser.
asked
Mar 20, 2018
by
anonymous
Description : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?
Answer :
The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.
asked
Mar 20, 2018
by
anonymous
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.
asked
Mar 20, 2018
by
anonymous
Answer :
A synchronous motor running with normal excitation adjusts to load increases essentially by increase in armature current.
asked
Mar 20, 2018
by
anonymous
Answer :
The coupling angle or load angle of synchronous motor is defined as the angle between the rotor and the stator poles of opposite polarity.
asked
Mar 20, 2018
by
anonymous
Description : In a synchronous motor which losses varies with load?
Answer :
In a synchronous motor, copper losses varies with load.
asked
Mar 18, 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 : Why synchronous machine is called doubly excited machine?
Answer :
Armature windings of synchronous machines either deliver 3 phase AC or absorb 3 phase AC source, whereas field windings are energized from DC source. Thus due to presence of AC on armature and DC on field windings, synchronous machines are often referred as doubly excited machines.
asked
Mar 18, 2018
by
anonymous
Answer :
The power factor of a single phase load can be calculated if the instruments available are three ammeters or three voltmeters.
asked
Mar 21, 2018
by
anonymous
Description : The effect of increasing load on a synchronous motor running with normal excitation is (A) Increase both its Ia and power factor. (B) Decrease Ia, but increase power factor. (C) Increase Ia, but decrease power factor (D) Decrease both Ia and power factor.
Answer :
The effect of increasing load on a synchronous motor running with normal excitation is Increase Ia, but decrease power factor
asked
Apr 28, 2018
by
anonymous
Description : In synchronous motor, does the winding losses vary with load?
Answer :
No, in the synchronous motor the winding losses do not vary with load.
asked
Mar 3, 2018
by
anonymous
Description : 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, 0.866 pu (B) 0.866 pu, 0.5 pu (C) 0.707 pu, 0.707 pu (D) 0.5 pu, 0.5 pu
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
asked
Apr 28, 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
Description : Can a synchronous condenser improve power factor?
Answer :
Yes, synchronous condenser can improve power factor.
asked
Mar 19, 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
Description : 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
Answer :
Power station having Load factor = 70%, capacity factor = 50%, used factor = 60%, maximum demand = 20MW then annual energy production is 122.8 GWh
asked
Apr 29, 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 : Minimum voltage regulation occurs when the power factor of the load is?
Answer :
Minimum voltage regulation occurs when the power factor of the load is leading.
asked
Mar 19, 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
Answer :
In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor.
asked
Mar 20, 2018
by
anonymous
Description : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) inversely proportional to α and Φ (C) directly proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α
Answer :
The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ
asked
Apr 28, 2018
by
anonymous
Description : In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load (A) The armature current increases and the power factor decreases (B) The armature current decreases and the power factor also decreases (C) The armature current decreases and the power factor increases but is lagging (D) The armature current decreases and the power factor increases and is leading
Answer :
In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load The armature current decreases and the power factor increases and is leading
asked
Apr 29, 2018
by
anonymous
Answer :
If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.
asked
Mar 20, 2018
by
anonymous
Description : If we change the excitation of synchronous machine will it affect on motor speed?
Answer :
No, If we change the excitation of synchronous machine it will not affect on motor speed.
asked
Mar 18, 2018
by
anonymous
Description : A three-phase synchronous motor connected to ac mains is running at full load and unity power factor. lf its shaft load is reduced by half and field current is held constant then its new power factor will be
Answer :
Leading
asked
Apr 28, 2018
by
anonymous
Answer :
The increased load during summer months is due to increased use of fans and air conditioners.
asked
Mar 20, 2018
by
anonymous
Description : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu
Answer :
The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu
asked
Apr 28, 2018
by
anonymous
Answer :
The power factor of a single-phase induction motor is usually lagging.
asked
Mar 20, 2018
by
anonymous
Answer :
An induction motor has relatively high power factor at near full load.
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 efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.
asked
Mar 20, 2018
by
anonymous
Answer :
In case one phase of a three-phase synchronous motor is short-circuited the motor will not start.
asked
Mar 20, 2018
by
anonymous
Description : The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?
asked
Mar 20, 2018
by
anonymous
Description : what will happen when excitation of an unloaded salient pole synchronous motor suddenly gets disconnected?
Answer :
When excitation of an unloaded salient pole synchronous motor suddenly gets disconnected the motor will stop.
asked
Mar 18, 2018
by
anonymous
Description : Three phase synchronous motor will have how many sliprings?
Answer :
Three phase synchronous motor will have two sliprings.
asked
Mar 18, 2018
by
anonymous
Description : A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling diode is open circuited, then the motor : (A) can be operated in first quadrant (B) can be operated in first & second quadrants (C) can be operated in first & fourth quadrants (D) cannot be operated
Answer :
A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling diode is open circuited, then the motor : can be operated in first & fourth quadrants
asked
Apr 30, 2018
by
anonymous
Description : Separately Excited DC motor
Answer :
Separately Excited DC motor
Answer :
The steady state stability of the power system can be increased by connecting lines in parallel.
asked
Mar 20, 2018
by
anonymous
Answer :
Slip-rings in a synchronous motor carry direct current.
asked
Mar 20, 2018
by
anonymous