Table of Contents
What is meant by synchronous reactance Mcq?
09․ Synchronous reactance of an alternator represents. armature reactance and leakage reactance. a reactance operating at synchronous speed. field winding reactance.
What is the formula of synchronous reactance?
X s = Synchronous reactance ( X L + X a )
What is the unit of synchronous reactance is?
A motor convention will be used and the synchronous reactance Xs assumed to be 1 per unit. From eqn (5.9):V = Ef + jXsIa neglecting resistance;at rated voltage: 1 = E f \ δ ¯ + j I a \ φ from which: I a \ φ = 1 – E f \ δ ¯ j = − j( 1 – E f \ δ ¯ ) per unit.
Which method gives large value of synchronous reactance?
synchronous impedance method
The synchronous impedance method or the EMF method is based on the concept of replacing the effect of armature reaction by an imaginary reactance. This method gives result which is higher than the original value.
What do you mean 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 synchronous impedance method?
The synchronous impedance method or EMF method is used to determine the voltage regulation of the larger alternators. The synchronous impedance method is based on the concept of replacing the effect of armature reaction by an imaginary reactance.
What is Potier reactance?
Potier reactance is the air gap reactance (leakage reactance) of the synchronous machine at full load (rated voltage and current of armature). Circuit Diagram For Determination of Portier Reactance.
Why it is called synchronous machine?
A synchronous generator is called “synchronous” because the waveform of the generated voltage is synchronized with the rotation of the generator. Each peak of the sinusoidal waveform corresponds to a physical position of the rotor. The magnetic field of the rotor is supplied by direct current or permanent magnets.
What is OCC and SCC?
Open circuit characteristic (OCC) and Short Circuit Characteristics (SCC) of a Synchronous generator.
What is synchronous reactance and synchronous impedance?
Synchronous Reactance and Synchronous Impedance. 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 the synchronous reactance of an armature?
The Synchronous Reactance 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 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.
What is the voltage drop due to synchronous reactance?
Voltage drop due to synchronous reactance. The armature resistance per phase R a causes a voltage drop per phase of IR a which is in phase with the armature current. The armature resistance per phase can be measured directly by voltmeter and ammeter ( ohm’s law ) method or by using a wheat stone bridge.