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 Synchronous condenser?
Answer :
Synchronous condenser Big advantage of synchronous condenser is their large temporary overload capability and good harmonics performance. Synchronous condenser is ... ;voltage levels. Synchronous condenser have slow speed of response.
Description : operating principle of condenser type microphone with neat diagram.
Answer :
Principle: When sound pressure moves the diapharam in, the capacitance increases, and when it moves out, the capacitance decreases. The change in capacitance results in change in out put voltage of microphone. ... in volts. Q= charge in coulombs C= capacitance in farad Diagram:
asked
Sep 2, 2019
by
anonymous
Description : Explain working of superheater and condenser.
Answer :
Working of Super heater: Super heater consist of group of tubes. Tubes are heated by absorbing temperature of flue gases passed over it . Superheated steam' is meant that steam which ... condensate is reused in boiler. This type of condenser is used for high capacity thermal power plant.
asked
Sep 8, 2018
by
anonymous
Description : State the function of cooling tower and condenser in thermal power station.
Answer :
1. Condenser: Function of condenser is to convert exhaust steam again into water by reducing its temperature with the help of cold water. Also it reduces back pressure of steam turbine 2 ... tower : The function of cooling tower is to reduce the temperature of water coming from condenser.
asked
Sep 8, 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 :
Synchronous motors are generally not self-starting because the direction of instantaneous torque reverses after half cycle.
asked
Mar 20, 2018
by
anonymous
Description : The damping winding in synchronous motor is generally used to?
Answer :
The damping winding in synchronous motor is generally used to provide starting torque and prevent hunting.
asked
Mar 18, 2018
by
anonymous
Description : Two synchronous generators G1, G2 are operating in parallel and are equally sharing KVAR (Lag) component of load. To shift part of KVAR from G2 to G1, while keeping terminal voltage fixed, the following action must be done
Answer :
Two synchronous generators G1, G2 are operating in parallel and are equally sharing KVAR (Lag) component of load. To shift part of KVAR from G2 to G1, while keeping terminal voltage fixed, the following action must be done Raise If1 and lower If2
asked
May 3, 2018
by
anonymous
Description : Asynchronous circuits are usually faster than synchronous circuits because
Answer :
Asynchronous circuits are usually faster than synchronous circuits because they are free running and do not depend on the frequency of the clock
asked
Apr 26, 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 :
Exciters of synchronous machines are d.c. shunt machines.
asked
Mar 20, 2018
by
anonymous
Description : List different starting methods of three phase synchronous motor. Explain any one of them.
Answer :
Different Starting Methods of Three Phase Synchronous Motor: As synchronous motor is not self starting, different methods of starting are as follows: 1) By using an Induction (Pony) motor 2) ... . The rotor gets pulled into synchronism and starts running at constant speed as a synchronous motor.
asked
May 7, 2020
by
anonymous
Description : Draw and explain V and inverted V curves for synchronous motor.
Answer :
V curves' and inverted V curves' for Synchronous Motor: V curve: V curve is a plot of the stator current versus field current for different constant loads. The graph is plotted ... Vcurves of synchronous motor. The highest point on each of these curves indicates unity power factor.
asked
May 7, 2020
by
anonymous
Description : List different torques in synchronous motor.
Answer :
Different Torques in Synchronous Motor: 1) Starting torque 2) Running torque 3) Pull-in torque 4) Pull-out torque
asked
May 7, 2020
by
anonymous
Description : Compare characteristics of asynchronous and synchronous transmission mode (four points).
Answer :
Synchronous transmission Asynchronous transmission 1. Synchronous transmission are synchronized by an external clock. 1. Asynchronous transmission are synchronized by special signals along the transmission ... for transferring a small amount of data as it is simple and economical.
asked
Aug 4, 2019
by
anonymous
Description : Compare synchronous and asynchronous counter.
Answer :
Asynchronous Counter Synchronous Counter In an Asynchronous Counter the output of one Flip Flop acts as the clock Input of the next Flip Flop. In a Synchronous Counter all the Flip Flop's are ... Also called as serial counter Also called as Parallel Counter
asked
Jul 31, 2019
by
anonymous
Description : Compare Asynchronous sequential and synchronous sequential circuits.
Answer :
SR. NO. ASYNCHRONOUS SEQUENTIAL CIRCUIT SYNCHRONOUS SEQUENTIAL CIRCUITS. 1 Output can be changed at any instant of time by changing the input Output changes at discrete ... the counter change state simultaneously. This is because all the flip-flops are clocked simultaneously.
asked
Jul 21, 2019
by
anonymous
Description : Synchronous vs asynchronous logic
Answer :
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asked
Jul 6, 2019
by
anonymous
Description : Damper winding in a synchronous motor
Answer :
Damper winding in a synchronous motor Serves to start the motor.
asked
May 8, 2018
by
anonymous
Description : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator
Answer :
In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as synchronous generator
asked
May 1, 2018
by
anonymous
Description : The 'Equal area criterion' for the determination of transient stability of a synchronous machine connected to an infinite bus (1) ignores line as well as synchronous machine resistance and shunt capacitances. (2) assumes accelerating power acting on the rotor as constant. (3) ignores the effect of voltage ... inherent damping present in the machine. (4) takes into consideration the possibility of machine losing synchronism after it has survived during the first swing.
Answer :
1
asked
Apr 30, 2018
by
anonymous
Description : Damper winding is provided in 3 phase synchronous motors to :
Answer :
Damper winding is provided in 3 phase synchronous motors to : provide starting torque and prevent hunting
asked
Apr 29, 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
Description : The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) (A) has q -axis current only (B) has d -axis current only (C) has both d and q axis currents (D) cannot be divided between q and d axis currents
Answer :
The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) has d -axis current only
asked
Apr 29, 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 : In a self-controlled synchronous motor fed from a variable frequency inverter (1) the rotor poles invariably have damper windings (2) there are stability problems (3) the speed of the rotor decides stator frequency (4) the frequency of the stator decides the rotor speed
Answer :
In a self-controlled synchronous motor fed from a variable frequency inverter the frequency of the stator decides the rotor speed
asked
Apr 29, 2018
by
anonymous
Description : During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s)
Answer :
During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s) only at C
asked
Apr 29, 2018
by
anonymous
Description : Two synchronous generators operating in parallel supply a common load of 2.5 MW. The frequency-power characteristics have a common slope of 1 MW/Hz and the no-load frequencies of the generators are 51.5 Hz and 51.0 Hz, respectively. Then the system frequency is (A) 50 Hz (B) 51 Hz (C) 51.25 Hz (D) 51.5 Hz
Answer :
Two synchronous generators operating in parallel supply a common load of 2.5 MW. The frequency-power characteristics have a common slope of 1 MW/Hz and the no-load frequencies of the generators are 51.5 Hz and 51.0 Hz, respectively. Then the system frequency is 50 Hz
asked
Apr 28, 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
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
Description : Torque angle for the synchronous machine is the angle between (A) stator magnetic field and rotor magnetic field (B) stator magnetic field and net magnetic field in the air gap (C) rotor magnetic field and net magnetic field in the air gap (D) excitation voltage and impedance voltage drop
Answer :
Torque angle for the synchronous machine is the angle between rotor magnetic field and net magnetic field in the air gap
asked
Apr 28, 2018
by
anonymous
Description : The armature reaction in a synchronous generator supplying leading power factor load is (A) magnetizing (B) demagnetizing (C) demagnetizing and cross-magnetizing (D) magnetizing and cross-magnetizing
Answer :
The armature reaction in a synchronous generator supplying leading power factor load is magnetizing and cross-magnetizing
asked
Apr 28, 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 : 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 :
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
Answer :
Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed.
asked
Mar 20, 2018
by
anonymous
Answer :
If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in damage to the starting winding.
asked
Mar 20, 2018
by
anonymous
Answer :
Slip-rings in a synchronous motor carry direct current.
asked
Mar 20, 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
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
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 :
Synchronsizing power of a synchronous machine is inversely proportional to the synchronous reactance.
asked
Mar 20, 2018
by
anonymous
Answer :
The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.
asked
Mar 20, 2018
by
anonymous
Answer :
A synchronous motor can develop synchronous torque at synchronous speed.
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
Answer :
In a synchronous motor, the armature current has large values for high and low excitation.
Answer :
The size of a synchronous motor decreases with the increase in flux density.
Answer :
The duration of sudden short-circuit test on a synchronous motor is usually about one second.
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