What is synchronous reactance?

The Synchronous Reactance (XS) 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 direct axis and quadrature axis reactance?

In a salient-pole machine, xaq, the quadrature-axis reactance is smaller than xad, the direct-axis reactance, since the flux produced by a given current component in that axis is smaller as the reluctance of the magnetic path consists mostly of the interpolar spaces.

What is synchronous reactance for synchronous machine?

As described in the armature winding notes, synchronous reactance is a combination of armature winding leakage reactance and a reactance used to represent armature reaction. The synchronous machine tests give the induced voltage and the current when armature reaction is greatest, for a range of field current values.

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 do you mean by synchronous reactance and synchronous impedance?

The synchronous impedance (ZS) is an imaginary impedance employed to account for the voltage effects in the armature circuit of the alternator, which is produced by the actual armature resistance, the actual armature leakage reactance, and the effect of the armature reaction.

What is unit of synchronous reactance?

When the load current flows through the armature winding it builds up the local flux which cuts the winding and counters EMF is generated. This effect produces armature reactance that is equal to 2πfl. The combination of leakage reactance along with armature reaction is called as synchronous reactance.

What is the axis in synchronous machine?

Salient Pole Synchronous Machine Two Rection Theory. The axis along the axis of the rotor is called the direct or the d axis. The axis perpendicular to the d axis is known as the quadrature or q axis. The direct axis flux path involves two small air gaps and is the path of the minimum reluctance.

What do you understand by synchronous impedance?

The synchronous impedance is determined from the O.C.C and S.C.C. It is the ratio of the open-circuit voltage to the short circuit current. When the O.C.C and S.C.C are linear, the synchronous impedance ZS is constant. The flux under test conditions is the same as that under load conditions.

What is meant by synchronous machine?

A synchronous machine is an electrical machine whose rotating speed is proportional to the frequency of the alternating current supply and independent of the load.

What is direct and quadrature inductance?

The axis along the axis of the rotor is called the direct or the d axis. The axis perpendicular to the d axis is known as the quadrature or q axis. The direct axis flux path involves two small air gaps and is the path of the minimum reluctance.

What is the synchronous impedance?

The synchronous impedance may be defined as the vector sum of the armature resistance and synchronous reactance. It is denoted as Z s.

What is a direct axis synchronous reactance?

A direct axis quantity is one whose magnetic effect is along the field pole axis. Field pole axis is also known as direct axis. Based on this fact, a direct axis synchronous reactance is defined as the reactance offered to the armature flux when the peak of armature mmf is directed along the direct axis. Let us understand this more clearly.

What is synchronous reactance (XS)?

The Synchronous Reactance (XS) 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 the equation for synchronous reactance in salient pole synchronous machine?

In case of salient pole synchronous machine, the air gap is non-uniform. Therefore, Xd > Xq. But due to uniform air gap in cylindrical pole synchronous machine, both direct and quadrature axis synchronous reactance are equal i.e. Xd = Xq.

What is synchronous reactance of a generator?

When the armature reactance is combined with the leakage reactance of the machine then, it is known as Synchronous reactance or Direct axis reactance. The machine offers synchronous reactance at steady state! Elaboration: When a sudden short circuit occurs for a synchronous generator operating under open circuit condition.