What is Zero sequence reactance?

What is Zero sequence reactance? 
by

1 Answer

Answer :

If a machine is operating with an earthed neutral, a system earth fault will give rise to zero sequence current in the machine. 
by

Related questions

What is meant by positive, negative and zero sequence reactance.

Description : What is meant by positive, negative and zero sequence reactance.

Last Answer : The reactance diagram of a power system, when formed using positive, negative and zero sequence reactances are called positive, negative and zero sequence reactance diagram resp.

When the Zero sequence reactance arises?

Description : When the Zero sequence reactance arises? 

Last Answer : If a machine is operating with an earthed neutral, a system earth fault will give rise to zero sequence current in the machine. 

When the negative sequence reactance arises?

Description : When the negative sequence reactance arises?

Last Answer : Negative sequence arises whenever there is any unbalance present in the system. Their effect is to set up a field rotating in opposite direction to the main field.

What is Negative sequence reactance?

Description : What is Negative sequence reactance?

Last Answer : Negative sequence can arise whenever there is any unbalance present in the system. Their effect is to setup a field rotating in opposite direction to the main field. 

Which of the following statements concerning AC circuits is correct? A. The power factor of a resistive circuit is always zero. B. True power in an inductive circuit always equals apparent power. C. Inductive reactance varies directly with the frequency and the inductance. D. Total opposition to the flow of alternating current depends upon the amount of reactive power.

Description : Which of the following statements concerning AC circuits is correct? A. The power factor of a resistive circuit is always zero. B. True power in an inductive circuit always equals apparent power. ... . D. Total opposition to the flow of alternating current depends upon the amount of reactive power.

Last Answer : Answer: C

Define zero sequence component.

Description : Define zero sequence component.

Last Answer : They has 3 vectors having equal magnitudes and displaced from each other by an angle zero degrees.

What is meant by positive, negative and zero sequence impedance.

Description : What is meant by positive, negative and zero sequence impedance.

Last Answer : The impedance of the circuit element for positive, negative and zero sequence component currents are called positive, negative and zero sequence impedances resp.

What are zero sequence components?

Description : What are zero sequence components?

Last Answer : The zero sequence components of a three phase unbalanced vectors consists of 3 vectors of equal magnitude and with zero phase displacement from each other.

What you mean by positive sequence, negative sequence and zero sequence of voltage?

Description : What you mean by positive sequence, negative sequence and zero sequence of voltage?

Last Answer : Positive phase sequence A system of vectors is said to have positive sequence if they are all of equal magnitude and are displaced by 120° with same time interval to arrive at fixed axis of reference ... in all the 3- phases. Such phase sequence is zero phase sequence.

Three factors responsible for the change in voltage as load is applied to an AC generator are: 1) the drop in resistance in the armature circuit, 2) the change in flux, and 3) the ____________. A. armature winding speed B. inductance load drop C. coil pitch factor D. armature reactance voltage drop

Description : Three factors responsible for the change in voltage as load is applied to an AC generator are: 1) the drop in resistance in the armature circuit, 2) the change in flux, and 3) the ____________. A. armature winding speed B. inductance load drop C. coil pitch factor D. armature reactance voltage drop

Last Answer : Answer: D

An AC circuit has a capacitive reactance of 30 ohms in addition to an inductive reactance of 40 ohms connected in series. What is the reactance of the circuit? A. 8.37 ohms B. 10.00 ohms C. 50.00 ohms D. 70.00 ohms

Description : An AC circuit has a capacitive reactance of 30 ohms in addition to an inductive reactance of 40 ohms connected in series. What is the reactance of the circuit? A. 8.37 ohms B. 10.00 ohms C. 50.00 ohms D. 70.00 ohms

Last Answer : Answer: B

The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip increases, rotor reactance decreases. B. The pullout point on the torque curve is about seven times the normal full load torque value. C. At stand still, stator current is 150% of normal. D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Description : The torque and current curves for a three-phase induction motor with a cage rotor, are shown in the illustration. Which of the following statements is true concerning the depicted curves? EL-0056 A. As slip ... D. If the motor is loaded to the point where 40% slip has resulted, it will stall.

Last Answer : Answer: D

In the illustrated circuit, one advantage of the capacitor coupling over direct coupling is ____________. EL-0048 A. as the frequency decreased the capacitive reactance (Xc) increases B. the amplifier becomes more efficient at lower capacitance. C. the arrangement allows the coupling of the signal while it isolates the biasing of each stage. D. good frequency response.

Description : In the illustrated circuit, one advantage of the capacitor coupling over direct coupling is ____________. EL-0048 A. as the frequency decreased the capacitive reactance (Xc) increases B. the amplifier becomes ... of the signal while it isolates the biasing of each stage. D. good frequency response.

Last Answer : Answer: C

The hook-on AC volt-ammeter consists essentially of a split-core and a rectifiertype instrument connected to the secondary winding of a _____________. A. potential transformer B. control transformer C. current transformer D. reactance transformer

Description : The hook-on AC volt-ammeter consists essentially of a split-core and a rectifiertype instrument connected to the secondary winding of a _____________. A. potential transformer B. control transformer C. current transformer D. reactance transformer

Last Answer : Answer: C

In an AC circuit, the inductive reactance of a coil varies with the _______________. A. resistance of the circuit B. frequency of the circuit C. voltage of the circuit D. current of the circuit

Description : In an AC circuit, the inductive reactance of a coil varies with the _______________. A. resistance of the circuit B. frequency of the circuit C. voltage of the circuit D. current of the circuit

Last Answer : Answer: B

In a series wound motor, the current passing through the field windings is also passing through the _____________. A. armature B. shunt field C. reactance comparator D. laminations

Description : In a series wound motor, the current passing through the field windings is also passing through the _____________. A. armature B. shunt field C. reactance comparator D. laminations

Last Answer : Answer: A

Decreasing the frequency in a capacitive circuit while maintaining a constant circuit voltage, will result in a/an _____________. A. increase in apparent power B. decrease in circuit current C. decrease in capacitive reactance D. decrease in total impedance

Description : Decreasing the frequency in a capacitive circuit while maintaining a constant circuit voltage, will result in a/an _____________. A. increase in apparent power B. decrease in circuit current C. decrease in capacitive reactance D. decrease in total impedance

Last Answer : Answer: B

An AC circuit has capacitance arranged in series. If the line voltage remains constant, the capacitive reactance value can be varied by changing the _____________. A. line frequency B. resistance C. number of commutating poles D. number of interpoles

Description : An AC circuit has capacitance arranged in series. If the line voltage remains constant, the capacitive reactance value can be varied by changing the _____________. A. line frequency B. resistance C. number of commutating poles D. number of interpoles

Last Answer : Answer: A

The component labeled 'CR1' in the circuit shown in the illustration __________________. EL-0085 A. varies its anode/cathode polarity depending on 'RL' current B. rectifies the varying voltage from the collector of 'Q1' C. acts as a low capacitive reactance to smooth ripple D. establishes a constant reference voltage for the base of 'Q1'

Description : The component labeled 'CR1' in the circuit shown in the illustration __________________. EL-0085 A. varies its anode/cathode polarity depending on 'RL' current B. rectifies the varying voltage from the ... reactance to smooth ripple D. establishes a constant reference voltage for the base of 'Q1'

Last Answer : Answer: D

Although saturable reactors are extremely useful in some applications, their gain is low because of ____________. A. core hysteresis losses B. inductive reactance in the control winding C. IR drop throughout the load winding D. all of the above

Description : Although saturable reactors are extremely useful in some applications, their gain is low because of ____________. A. core hysteresis losses B. inductive reactance in the control winding C. IR drop throughout the load winding D. all of the above

Last Answer : Answer: A

A saturable-core reactor operates on the principle of controlling a load winding's inductance by varying the core's _____________. A. dielectric B. permeability C. reactance D. inductance

Description : A saturable-core reactor operates on the principle of controlling a load winding's inductance by varying the core's _____________. A. dielectric B. permeability C. reactance D. inductance

Last Answer : Answer: B

When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the leakage of current along the surface of dirty insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation

Description : When a megohmmeter is used to test insulation, the gradual rise of the pointer reading as a result of continued cranking, is caused by _____________. A. good conductor resistance B. the ... insulation C. the inductive reactance of the windings D. the dielectric-absorption effect of the insulation

Last Answer : Answer: D

AC circuits develop resistance, inductance, and capacitance. The inductive reactance of a circuit is expressed in _____________. A. ohms B. mhos C. henrys D. farads

Description : AC circuits develop resistance, inductance, and capacitance. The inductive reactance of a circuit is expressed in _____________. A. ohms B. mhos C. henrys D. farads

Last Answer : Answer: A

The combined effect of inductive reactance, capacitive reactance, and resistance in an AC series circuit is known as _____________. A. reactance B. total reactance C. impedance D. resonance

Description : The combined effect of inductive reactance, capacitive reactance, and resistance in an AC series circuit is known as _____________. A. reactance B. total reactance C. impedance D. resonance

Last Answer : Answer: C

The ratio of the effective value of the counter EMF in volts, to the effective value of the current in amperes is called _____________. A. impedance factor B. capacitive reactance C. inductive reactance D. root mean square

Description : The ratio of the effective value of the counter EMF in volts, to the effective value of the current in amperes is called _____________. A. impedance factor B. capacitive reactance C. inductive reactance D. root mean square

Last Answer : Answer: C

On tank vessels with an electrically-driven capstan, the motor should be meggered periodically to test _____________. A. insulation resistance B. eddy currents C. capacitance D. armature reactance

Description : On tank vessels with an electrically-driven capstan, the motor should be meggered periodically to test _____________. A. insulation resistance B. eddy currents C. capacitance D. armature reactance

Last Answer : Answer: A

The purpose of the capacitor within component 'B' of the circuit shown in the illustration is to ____________. EL-0081 A. prolong the life of the component's contacts B. discharge the neon within the envelope C. counteract the inductive reactance in the circuit D. store power to operate the circuit should 'D' open

Description : The purpose of the capacitor within component 'B' of the circuit shown in the illustration is to ____________. EL-0081 A. prolong the life of the component's contacts B. discharge the neon within ... the inductive reactance in the circuit D. store power to operate the circuit should 'D' open

Last Answer : Answer: A

AC circuits possess characteristics of resistance, inductance, and capacitance. The capacitive reactance of a circuit is expressed in _____________. A. ohms B. mhos C. henrys D. farads

Description : AC circuits possess characteristics of resistance, inductance, and capacitance. The capacitive reactance of a circuit is expressed in _____________. A. ohms B. mhos C. henrys D. farads

Last Answer : Answer: A

Tightly knit metal braid wire can be used with a printed circuit board when ___________. A. conductor flexibility is required B. desoldering components in the circuit C. electrically produced magnetic fluxes would cause inaccuracies in adjacent components D. reactance in the circuit must be kept to a minimum

Description : Tightly knit metal braid wire can be used with a printed circuit board when ___________. A. conductor flexibility is required B. desoldering components in the circuit C. electrically produced magnetic ... cause inaccuracies in adjacent components D. reactance in the circuit must be kept to a minimum

Last Answer : Answer: B

What Is Meant By Reactance Voltage?

Description : What Is Meant By Reactance Voltage?

Last Answer : An armature coil has certain self inductance. When coil undergoes commutation, there is change in current (di) in that coil and the commutation takes certain time(dt). Thus there is self-induced emf ... by L(di/dt). This EMF induced in the coil undergoing commutation is called reactance voltage.

Why synchronous generators are to be constructed with more synchronous reactance and negligible resistance?

Description : Why synchronous generators are to be constructed with more synchronous reactance and negligible resistance?

Last Answer : The presence of more resistance in the Synchronous generators will resist or oppose their synchronous operation. More reactance in the generators can cause good reaction between the two and help the ... to remain in synchronism in spite of any disturbance occurring in any one of the generators

What is synchronous reactance?

Description : What is synchronous reactance?

Last Answer : It is the combination of leakage reactance and armature reactance

How the leakage reactance of the transformer is reduced?

Description : How the leakage reactance of the transformer is reduced?

Last Answer : In transformers the leakage reactance is reduced by interleaving the high voltage and low voltage winding.

Give equivalent resistance, reactance and impedance referred to secondary circuit.

Description : Give equivalent resistance, reactance and impedance referred to secondary circuit.

Last Answer : Req = R2 +R1' = R2+ R1'/a² Xeq = X2 +X1' = X2+ X1'/a² Zeq = Z2 + Z1' = Z2+ Z1'/a² where a=T1/T2

Give equivalent resistance, reactance and impedance referred to primary circuit.

Description : Give equivalent resistance, reactance and impedance referred to primary circuit.

Last Answer : Req = R1 +R2' = R1+a² R2' Xeq = X1 +X2' = X1+a² X2' Zeq = Z1 +Z2' = Z1+a² Z2' where a=T1/T2

Name any two methods of reducing short circuit current/ By providing neutral reactance.

Description : Name any two methods of reducing short circuit current/ By providing neutral reactance.

Last Answer : By introducing a large value of shunt reactance between buses.

What are the approximations made in reactance diagram?

Description : What are the approximations made in reactance diagram?

Last Answer : The neutral reactances are neglected. The resistances are neglected. All static loads and induction motors are neglected.

What is impedance and reactance diagram?

Description : What is impedance and reactance diagram?

Last Answer : The impedance diagram is the equivalent circuit of power system in which the various components of power system are represented by their approximate equivalent circuits. The impedance diagram is ... ddiagram can be obtained from impedance diagram if all the resistive components are neglected.

What is meant by reactance diagram.

Description : What is meant by reactance diagram.

Last Answer : Omitting all static loads ,all resistance. The magnetizing components of each transformer and the capacitance of the transmission line are reduced from the impedance diagram is called reactance diagram

What is capacitance and capacitive reactance?

Description : What is capacitance and capacitive reactance?

Last Answer : Capacitance The property of a capacitor to store electrical energy in it, when it is connected to an electric supply is called capacitance. Unit for measurement is farad. Capacitor store an electric ... called capacitive reactance and it denoted by the letter XC. The unit for measurement is ohm.

What is inductance and inductive reactance?

Description : What is inductance and inductive reactance?

Last Answer : Inductance A coil carrying alternating current produces an alternating flux, which causes to link with same coil and produces an emf in the coil, which opposes the applied emf. This property is known ... is known as inductive reactance and denoted by the letter XL. The unit for measurement is ohm.

In series RLC circuit at resonant a) Voltage is in phase with current b) Current is maximum c) Inductive reactance = Capacitive reactance d) All of the above

Description : In series RLC circuit at resonant a) Voltage is in phase with current b) Current is maximum c) Inductive reactance = Capacitive reactance d) All of the above

Last Answer : Ans: All of the above

Two transformers operating in parallel will share the load depending upon their (A) Rating. (B) Leakage reactance. (C) Efficiency. (D) Per-unit impedance.

Description : Two transformers operating in parallel will share the load depending upon their (A) Rating. (B) Leakage reactance. (C) Efficiency. (D) Per-unit impedance.

Last Answer : Ans: A Transformers having higher kVA rating will share more load.

The charging reactance of 50 Km length of line is 1500Ω. The charging reactance for 100Km length of line will be (A) 1500 Ω (B) 3000 Ω (C) 750 Ω (D) 600 Ω

Description : The charging reactance of 50 Km length of line is 1500Ω. The charging reactance for 100Km length of line will be (A) 1500 Ω (B) 3000 Ω (C) 750 Ω (D) 600 Ω

Last Answer : Ans: B Characteristic reactance per km = 1500/50 = 30 ohms ∴ Characteristic reactance per 100km = 30 x 100 = 3000 ohms

The voltage at the two ends of a transmission line are 132 KV and its reactance is 40 ohm. The Capacity of the line is (A) 435.6 MW (B) 217.8 MW (C) 251.5 MW (D) 500 MW

Description : The voltage at the two ends of a transmission line are 132 KV and its reactance is 40 ohm. The Capacity of the line is (A) 435.6 MW (B) 217.8 MW (C) 251.5 MW (D) 500 MW

Last Answer : (A) 435.6 MW

The synchronous reactance of the synchronous machine is ______________. (A) Ratio between open circuit voltage and short circuit current at constant field current (B) Ratio between short circuit voltage and open circuit current at constant field current (C) Ratio between open circuit voltage and short circuit current at different field current (D) Ratio between short circuit voltage and open circuit current at different field current

Description : The synchronous reactance of the synchronous machine is ______________. (A) Ratio between open circuit voltage and short circuit current at constant field current (B) Ratio between short circuit ... (D) Ratio between short circuit voltage and open circuit current at different field current

Last Answer : Ans. A The Synchronous reactance of a synchronous machine is a total steady state reactance, presented to applied voltage, when rotor is running synchronously without excitation. Therefore , XS = Ef / IS = Emf of OC for same If / short circuit current

Consider the following salient points in a stress-strain curve of a mild steel bar: 1. Yield point 2. Braking point 3. Yield plateau 4 . Proportionality limit 5. Ultimate point The correct sequence in which they occur while testing the mild steel bar in tension from initial zero strain to failure is (a) 4, 1, 2, 3 and 5 (b) 1, 4, 3, 5 and 2 (c) 4, 1, 3, 5 and 2 (d) 1, 4, 2, 3 and 5

Description : Consider the following salient points in a stress-strain curve of a mild steel bar: 1. Yield point 2. Braking point 3. Yield plateau 4 . Proportionality limit 5. Ultimate point The correct sequence in which they occur while testing the mild ... , 5 and 2 (c) 4, 1, 3, 5 and 2 (d) 1, 4, 2, 3 and 5

Last Answer : (c) 4, 1, 3, 5 and 2

A power system is subjected to a fault which makes the zero sequence component of current equal to zero

Description :  A power system is subjected to a fault which makes the zero sequence component of current equal to zero. The nature of fault current is: A) Double line to ground fault B) Line to line fault C) Line to ground fault D) Three-phase to ground fault

Last Answer :  A power system is subjected to a fault which makes the zero sequence component of current equal to zero. The nature of fault current is: Line to line fault

The zero sequence current of a generator for line to ground fault is j 2.4 p.u. The current through the neutral

Description : The zero sequence current of a generator for line to ground fault is j 2.4 p.u. The current through the neutral during the fault is (a) j 0.8 p.u (b) j 2.4 p.u. (c) j 0.24 p.u. (d) j 7.2 p.u. 

Last Answer : j7.2

Zero-sequence current is used for relaying purpose only in the case of

Description : Zero-sequence current is used for relaying purpose only in the case of   (a) Phase over current relay (b) Phase impedance relay (c) Ground over current relay (d) Ground impedance relay

Last Answer : Zero-sequence current is used for relaying purpose only in the case of Ground impedance relay