Distinguish between synchronous phase modifier and synchronous condenser

Distinguish between synchronous phase modifier and synchronous condenser
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1 Answer

Answer :

A synchronous motor used to change the power factor or power factor in the supply lines is called synchronous phase modifier.
A synchronous motor operated at no load with over excitation condition to draw large leading reactive current and power is called a synchronous condenser.
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Related questions

How the synchronous motor can be used as s synchronous condenser?

Description : How the synchronous motor can be used as s synchronous condenser?

Last Answer : Synchronous motor is operated on over excitation so as to draw leading reactive current and power from the supply lines. This compensates the lagging current and power requirement of the load making ... to become unity. The motor does the job of capacitors and hence called as synchronous condenser.

What is synchronous condenser?

Description : What is synchronous condenser?

Last Answer : An over-excited synchronous motor under no load , used for the improvement of power factor is called as synchronous condenser because, like a capacitor it takes a leading current.

What could be the reasons if a 3-phase synchronous motor fails to start?

Description : What could be the reasons if a 3-phase synchronous motor fails to start?

Last Answer : It is usually due to the following reasons a. Voltage may be too low. b. Too much starting load. c. Open circuit in one phase or short circuit. d. Field excitation may be excessive

What is the effect on speed if the load is increased on a 3 phase synchronous motor?

Description : What is the effect on speed if the load is increased on a 3 phase synchronous motor?

Last Answer : The speed of operation remains constant from no load to maximum load in the motor operating at constant frequency bus bars.

Hunting of a synchronous motor:

Description : Hunting of a synchronous motor:

Last Answer : When the mechanical load is constant, the rotor settles down to an absolutely constant speed with the torque angle fixed by the particular delivered power. When there is a change in load the rotor speed ... are short circuited; copper bars are embedded in the faces of the field poles of the motor.

A synchronous motor starts as usual but fails to develop its full torque. What could it be due to?

Description : A synchronous motor starts as usual but fails to develop its full torque. What could it be due to?

Last Answer : a. Exciter voltage may be too low. b. Field spool may be reversed c. There may be either open-circuit or short-circuit in the field.

In what way synchronous motor is different from other motors?

Description : In what way synchronous motor is different from other motors?

Last Answer : All dc and ac motors work on the same principle. Synchronous motor operates due to magnetic locking taking place between stator and rotor magnetic fields.

State the characteristic features of synchronous motor.

Description : State the characteristic features of synchronous motor.

Last Answer : a. the motor is not inherently self starting b. The speed of operation is always in synchronous with the supply frequency irrespective of load conditions c. The motor is capable of operating at any power factor.

Write the applications of synchronous motor.

Description : Write the applications of synchronous motor.

Last Answer : a. Used for power factor improvement in sub-stations and in industries. b. As synchronous condenser c. Used for constant speed applications

What are V and inverted V curves of synchronous motor ?

Description : What are V and inverted V curves of synchronous motor ?

Last Answer : The variation of magnitude of line current with respect to the field current is called V curve . The variation of power factor with respect to the field current is called inverted V curve.

Why a synchronous motor is a constant speed motor?

Description : Why a synchronous motor is a constant speed motor?

Last Answer : When load increase in synchronous motor the load angle δ also increases but speed remains constant. The further increase in load cause further increase in load angle. When load angle reaches ... out of synchronism. Hence the motor rotates at synchronous speed otherwise it comes out of synchronism.

Why damper windings are used in synchronous motor? Or How synchronous motor is started as squirrel cage motor?

Description : Why damper windings are used in synchronous motor? Or How synchronous motor is started as squirrel cage motor?

Last Answer : The damper winding consists of short circuited copper bars embedded in the the face of the rotor poles. When an ac supply is provided to stator of a 3-phase synchronous motor, stator winding produces ... magnetic field and damper winding is zero. Hence there will be no emf induced in damper winding.

What are the methods of starting synchronous motor?

Description : What are the methods of starting synchronous motor?

Last Answer : 1. Pony motor starting( using ac or dc motor) 2. Starting as squirrel cage Induction motor or using damper winding 3. Starting as slip ring Induction motor or synchronous motor 4. Using dc machine coupled to it.

Why synchronous motor is not self starting?

Description : Why synchronous motor is not self starting?

Last Answer : Synchronous motor is a doubly excited machine i.e two electrical inputs are provided to it. It's stator winding which consists of a 3 phase winding is provided with 3 phase supply and rotor ... due to attractive or repulsive force and remain in standstill condition. Hence it is not self starting.

What is critical excitation?

Description : What is critical excitation?

Last Answer : The excitation for which power factor of the synchronous motor is unity and the back emf is equal to supply voltage.

What is over excitation?

Description : What is over excitation?

Last Answer : The excitation for which power factor of the synchronous motor is leading and the back emf is greater than supply voltage.

What is under excitation?

Description : What is under excitation?

Last Answer : The excitation for which power factor of the synchronous motor is lagging and the back emf is less than supply voltage.

What is normal excitation?

Description : What is normal excitation?

Last Answer : The excitation for which power factor of the synchronous motor is lagging and the back emf is equal to supply voltage.

What is pull out torque?

Description : What is pull out torque?

Last Answer : The maximum torque developed by the motor without pulling out of synchronism is called pull out torque. Its value varies from 1.5 to 3.5 times full load torque.

What is pull in torque?

Description : What is pull in torque?

Last Answer : The torque which is required to pull the motor into synchronism when it is running as induction motor is called pull in torque.

What are the effects of hunting?

Description : What are the effects of hunting?

Last Answer : Loses synchronism Develops mechanical stress on rotor shaft Increase machine losses Increase temperature of machine

What is hunting?

Description : What is hunting?

Last Answer : The sudden changes of load on synchronous motor set up oscillations in the rotor. Such oscillation of rotor about its new equilibrium position is called hunting.

What is the function of damper winding?

Description : What is the function of damper winding?

Last Answer : To provide starting torque To prevent or minimize hunting

What is pony motor starting?

Description : What is pony motor starting?

Last Answer : In this method the rotor is made to rotate by some external device called pony motors. Once the rotor attains synchronous speed, the DC excitation to the rotor is switched on. Once synchronism is established the pony motor is decoupled. The synchronous motor continuously runs at synchronous speed.

What is synchronous condenser or phase advancer?

Description : What is synchronous condenser or phase advancer?

Last Answer : An over excited synchronous motor takes leading current just like a condenser and gives leading power factor. A synchronous motor, which I used only for the purpose of improving power factor, can be called as synchronous condenser or phase advancer.

In order to improve the power factor ___ device is employed in the substation a) Synchronous condenser b) Synchronous reactor c) Series Capacitors d) None of the above

Description : In order to improve the power factor ___ device is employed in the substation a) Synchronous condenser b) Synchronous reactor c) Series Capacitors d) None of the above

Last Answer : Ans: A

What is synchronous Condenser? Where and why it is used?

Description : What is synchronous Condenser? Where and why it is used?

Last Answer : An overexcited synchronous motor running at no- load and used for power-factor correction is called synchronous condenser. It is also called synchronous capacitor. It is used in a large system where the use of static capacitor is inefficient and expensive. It is used for power-factor correction.

What is meant by synchronous condenser?

Description : What is meant by synchronous condenser?

Last Answer : An over excited synchronous motor running on no load is known as synchronous condenser. It is used to improve the power factor of the system.

What is Synchronous Condenser ?

Description : What is Synchronous Condenser ?

Last Answer : When an over-excited synchronous motor is connected to a line to enhance the power factor without load , it is called a synchronous condenser.

What is a synchronous condenser?

Description : What is a synchronous condenser?

Last Answer : A synchronous condenser is a device identical to a synchronous motor, whose shaft is not connected to anything but spins freely. Its purpose is not to convert electric power to mechanical power or vice ... or absorb reactive power as needed to adjust the grid's voltage, or to improve power factor.

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

Description : 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

Can a synchronous condenser improve power factor?

Description : Can a synchronous condenser improve power factor?

Last Answer : Yes, synchronous condenser can improve power factor.

where the synchronous condenser are generally installed ?

Description : where the synchronous condenser are generally installed ?

Last Answer : the synchronous condenser are generally installed at receiving end side of transmission line 

What is Synchronous condenser?

Description : What is Synchronous condenser?

Last 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.

Phase modifier is normally installed

Description : Phase modifier is normally installed

Last Answer : Phase modifier is normally installed in case of long lines

A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Description : A four pole, 60 Hz, three-phase synchronous motor comes up to 1760 RPM when started as an induction motor. What is the percent slip after the rotor field is energized? A. 0 B. 1.1 C. 2.2 D. 3.3

Last Answer : Answer: A

The direction of propeller shaft rotation in a turbo-electric synchronous propulsion drive motor is changed by reversing the _____________. A. polarity of the propulsion motor B. polarity of the propulsion generator C. phase sequence of power to the motor D. phase sequence of power to the generator

Description : The direction of propeller shaft rotation in a turbo-electric synchronous propulsion drive motor is changed by reversing the _____________. A. polarity of the propulsion motor B. polarity of the propulsion generator C. phase sequence of power to the motor D. phase sequence of power to the generator

Last Answer : Answer: C

A shaded-pole motor is a ____________. A. synchronous motor B. three-phase induction motor C. compound-wound motor D. single-phase induction motor

Description : A shaded-pole motor is a ____________. A. synchronous motor B. three-phase induction motor C. compound-wound motor D. single-phase induction motor

Last Answer : Answer: D

Why a 3-phase synchronous machine will always run at synchronous speed?

Description : Why a 3-phase synchronous machine will always run at synchronous speed?

Last Answer : Because of the magnetic coupling between the stator poles and rotor poles the motor runs exactly at synchronous speed.

A single phase Hysteresis motor (A) can run at synchronous speed only (B) can run at sub synchronous speed only (C) can run at synchronous and super synchronous speed (D) can run at synchronous and sub synchronous speed

Description : A single phase Hysteresis motor (A) can run at synchronous speed only (B) can run at sub synchronous speed only (C) can run at synchronous and super synchronous speed (D) can run at synchronous and sub synchronous speed

Last Answer : Ans: A The rotor revolves synchronously because the rotor poles magnetically lock up with the revolving stator poles of opposite polarity

The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm

Description : The synchronous speed for a 3 phase 6-pole induction motor is 1200 rpm. If the number of poles is now reduced to 4 with the frequency remaining constant, the rotor speed with a slip of 5% will be _________. (A) 1690 rpm (B) 1750 rpm (C) 1500 rpm (D) 1710 rpm

Last Answer : (D) 1710 rpm

The speed-torque characteristics of a DC series motor are approximately similar to those of the _________motor. (A) universal (B) synchronous (C) DC shunt (D) two-phase

Description : The speed-torque characteristics of a DC series motor are approximately similar to those of the _________motor. (A) universal (B) synchronous (C) DC shunt (D) two-phase

Last Answer : Ans: A Universal motor has same characteristics as DC series motor and also known as an a.c series motor.

In a 3-phase synchronous motor (A) the speed of stator MMF is always more than that of rotor MMF. (B) the speed of stator MMF is always less than that of rotor MMF. (C) the speed of stator MMF is synchronous speed while that of rotor MMF is zero. (D) rotor and stator MMF are stationary with respect to each other.

Description : In a 3-phase synchronous motor (A) the speed of stator MMF is always more than that of rotor MMF. (B) the speed of stator MMF is always less than that of rotor MMF. (C) the speed of ... speed while that of rotor MMF is zero. (D) rotor and stator MMF are stationary with respect to each other.

Last Answer : Ans: D Because, Motor is magnetically locked into position with stator, the rotor poles are engaged with stator poles and both run synchronously in same direction Therefore, rotor & stator mmf are stationary w.r.t each other.

The relative speed between the magnetic fields of stator and rotor under steady state operation is zero for a (A) dc machine. (B) 3 phase induction machine. (C) synchronous machine. (D) single phase induction machine.

Description : The relative speed between the magnetic fields of stator and rotor under steady state operation is zero for a (A) dc machine. (B) 3 phase induction machine. (C) synchronous machine. (D) single phase induction machine.

Last Answer : Ans: all options are correct

nswer: Option B 559. Heat release during phase change is observed in case of a/an (A) Boiler (B) Condenser (C) Evaporator (D) All (A), (B) & (C)

Description : nswer: Option B 559. Heat release during phase change is observed in case of a/an (A) Boiler (B) Condenser (C) Evaporator (D) All (A), (B) & (C)

Last Answer : (B) Condenser

Which of the device is employed in substation to limit the short circuit current in the power system: a) Shunt condenser b) Reactor c) Series capacitor d) Shunt capacitor

Description : Which of the device is employed in substation to limit the short circuit current in the power system: a) Shunt condenser b) Reactor c) Series capacitor d) Shunt capacitor

Last Answer : Ans: B

In the illustration if the compressor fails to start but the condenser fan motor is running the problem is _______. EL-0042 A. no power between L1 and L2 B. the yellow wire is open at the freezer temperature control switch C. the overload is open D. the blue wire from the defrost heater is open

Description : In the illustration if the compressor fails to start but the condenser fan motor is running the problem is _______. EL-0042 A. no power between L1 and L2 B. the yellow wire is open at the freezer temperature control switch C. the overload is open D. the blue wire from the defrost heater is open

Last Answer : Answer: C

A device used in an electrical circuit to change alternating current to direct current, is known as a _____________. A. current transformer B. rectifier C. condenser D. shunt

Description : A device used in an electrical circuit to change alternating current to direct current, is known as a _____________. A. current transformer B. rectifier C. condenser D. shunt

Last Answer : Answer: B

In the illustration if the compressor fails to start but the condenser fan motor is running the problem is _______. EL-0043 A. no power between L1 and L2 B. the yellow wire is open at the freezer temperature control switch C. the overload is open D. the blue wire from the defrost heater is open

Description : In the illustration if the compressor fails to start but the condenser fan motor is running the problem is _______. EL-0043 A. no power between L1 and L2 B. the yellow wire is open at the freezer temperature control switch C. the overload is open D. the blue wire from the defrost heater is open

Last Answer : Answer: C

What are the purposes of bleed condenser?

Description : What are the purposes of bleed condenser?

Last Answer : The purposes of bleed condenser are, a. To cool the bleed water, which goes to bleed cooler.  b. To provide cool hot water to the PHT purification system.