What is Armature leakage reactance?

Leakage reactance in Synchronous machine. It is the reactance due to flux setup by armature windings, but not crossing the air gap. It can be divided into end-winding leakage and slot leakage.

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Just so, what is armature reactance?

‚ch?r ‚rē′ak·t?ns] (electromagnetism) The inductive reactance due to the flux produced by the armature current and enclosed by the conductors in the armature slots and the end connections.

Beside above, what is meant by synchronous impedance? DEFINITION : The synchronous impedance of an alternator, for a given armature current, a given field excitation and normal speed, may be defined as an impedance, which, if inserted in a separate external circuit, would permit the same flow of current, with an impressed pressure equal to the open circuit voltage of the

Also know, how do you find synchronous reactance?

1. If it is calculated at synchronous angular frequency ωs , it is Xs = ωsL then it is called synchronous reactance.
2. Synchronous reactance Xs is the sum of ,
3. Xs = XL + Xa , where.
4. XL = leakage reactance , and.
5. Xa = fictitious reactance to account for the armature reaction effect.
6. ( XL and Xa are calculated at ωs )

What is slot leakage flux?

Leakage flux in the induction motor takes place due to current flows through the core of the induction motor. Leakage flux takes place due to the Eddy current at the core. The leakage flux takes place in the airgap between the stator and rotor .

Related Question Answers

What do you mean by flux?

The noun flux describes something that constantly changes. If your likes, dislikes, attitudes, dreams, and even friends are changing all the time, you may be in flux. Flux can also mean being unsure about a decision. Another kind of flux is liquid moving or flowing, like the flux of water under a sheet of melting ice.

What is back EMF How is it created?

A motor has coils turning inside magnetic fields, and a coil turning inside a magnetic field induces an emf. This emf, known as the back emf, acts against the applied voltage that's causing the motor to spin in the first place, and reduces the current flowing through the coils of the motor.

What is synchronous reactance?

The Synchronous Reactance (X_S) is the imaginary reactance employed to account for the voltage effects in the armature circuit produced by the actual armature leakage reactance and by the change in the air gap flux caused by the armature reaction.

What is armature winding?

The armature winding is the main current-carrying winding in which the electromotive force or counter-emf of rotation is induced. The current in the armature winding is known as the armature current. The location of the winding depends upon the type of machine.

What are Interpoles?

Interpoles are small pole pieces connected between the main field poles used to help correct armature reaction. Interpoles are connected in series with the armature. Interpole windings are wound with few turns of large wire similar to series field winding.

What is reactance voltage in commutation?

Reactance Voltage: The voltage rise in the short circuit coil due to inductive property of the coil, which opposes the current reversal in it during the commutation period, is called the reactance voltage. We can produce reversing emf in two ways. By brush shifting.

Why there is no armature reaction in induction machines?

Concept of armature reaction comes when there is presence of two magnetic field or we can say that armature reaction occurs in doubly excited machines. In case of Induction Machine there is only one magnetic field is presence, i.e singly excited machine so there is not any armature reaction.

Why does the armature winding possess reactance?

Armature Leakage Reactance When armature carries a current, it produces its own flux. Some part of this flux completes its path through the air around the conductors itself. Note : This leakage flux makes the armature winding inductive in nature. So winding possesses a leakage reacatnce, in addition to the resistance.

What is an air gap line?

Air gap, also airgap¹⁾ or air-gap²⁾ - is a non-magnetic part of a magnetic circuit. It is usually connected magnetically in series with the rest of the circuit, so that a substantial part of the magnetic flux flows through the gap.

Why is synchronous reactance not constant?

Synchronous reactance comprises of armature reaction and leakage reactance . For salient pole machines the synchronous reactance will not be constant due to non Uniform air gap. So the reactance is divided into q Axis and d Axis.

What is saturated synchronous reactance?

Saturated reactance is calculated on the basis of (1) actual open circuit characteristics i.e. the one showing some degree of saturation (2) short circuit characteristics which is a straight line. The reactance so calculated (saturated reactance) is therefore not constant but decreases with field excitation.

What is XD and XQ in synchronous machine?

For such conditions of Φa the stator winding is characterised by: Xaq – quadrature-axis armature reaction reactance. Xl + Xad = Xd – direct-axis synchronous reactance, Xl + Xaq = Xq – quadrature-axis synchronous reactance.

Why SCC is a straight line?

The SCC is a straight line, while the OCC is a curve in a synchronous machine test. The OCC is a straight line till saturation point. As field current increases, Emf induced increases proportionally (according to emf eqn of synchronous machines). Thus we get a straight line.

What are the different components of synchronous impedance?

The voltage Ez which forces the current I1 through the impedance of the motor windings produces a voltage drop I1Zs. The impedance Zs is called the synchronous impedance and is composed of two parts. One part is Ra+jXa, which is the resistance and leakage reactance of the winding.

What is direct axis and quadrature axis?

The axis of the rotor pole is generally. called as direct-axis (d-axis), whereas. the axis in quadrature to the rotor pole is called quadrature axis (q-axis). As in AC motors (salient pole) field winding rotates, so does the the d-axis and q-axis spatially.

Why synchronous motors are not self starting?

Key Point : As a result, the average torque exerted on the rotor is zero. And hence the synchronous motor is not self starting. This is because the speed with which rotating magnetic field is rotating is so high that it is unable to rotate the rotor from its initial position, due to the inertia of the rotor.

What is direct axis Subtransient reactance?

The reactance during these first two or three cycle is least and the short circuit current is high. This reactance is called subtransient reactance and is denoted by X”. Since the short circuit current of the alternator lags behind the voltage by 90 degree, the reactance involved are direct axis reactance.

What is reactance physics?

In electric and electronic systems, reactance is the opposition of a circuit element to the flow of current due to that element's inductance or capacitance. As frequency goes up, inductive reactance also goes up and capacitive reactance goes down.

How do you calculate synchronous impedance?

Calculation of Synchronous Impedance Determine the value of short circuit current I_sc and gives the rated alternator voltage per phase. The synchronous impedance Z_S will then be equal to the open circuit voltage divided by the short circuit current at that field current which gives the rated EMF per phase.