The Synchronous Impedance Method or Emf Method is based on the concept of replacing the effect of armature reaction by an imaginary reactance. For calculating the regulation, the synchronous method requires the following data; they are the armature resistance per phase and the open circuit characteristic..
Also to know is, 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
Similarly, what is the 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.
Moreover, what are the drawbacks of synchronous impedance method?
This method is also known as the EMF method for determining and calculating the voltage regulation which gives out the large values of reactance. This is considered to be a very easy method but the only disadvantage it has is that it gives out the negative results. Further, it will state out poorer voltage regulation.
What are the components of synchronous impedance?
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.
Related Question Answers
What is armature reaction?
Armature reaction is effect of armature flux on main field flux. Basically there are two windings in a dc motor - Armature winding (on rotor) and field winding (on stator). When we excite the field winding, it produces a flux which links with the armature. This is referred to as armature reaction.Why MMF method is optimistic?
The EMF method is also called pessimistic method as the value of regulation obtained is much more than the actual value. The MMF method is also called optimistic method as the value of regulation obtained is much less than the actual value.What is the working principle of synchronous generator?
Working Principle of Synchronous Generator The synchronous generator works on the principle of Faraday laws of electromagnetic induction. The electromagnetic induction states that electromotive force induced in the armature coil if it is rotating in the uniform magnetic field.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.How does a synchronous generator work?
The synchronous generator rotor and shaft or turbine blades are mechanically coupled to each other and rotates at synchronous speed. Thus, the magnetic flux cutting produces an induced emf which causes the current flow in armature conductors.Why EMF method is called synchronous impedance method?
The Synchronous Impedance Method or Emf Method is based on the concept of replacing the effect of armature reaction by an imaginary reactance. For calculating the regulation, the synchronous method requires the following data; they are the armature resistance per phase and the open circuit characteristic.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. 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 synchronous speed?
In a motor, synchronous speed is the speed at which the magnetic field rotates. Depending on motor design, the actual mechanical speed may be equivalent (synchronous motor) or slightly smaller (asynchronous motor). The synchronous speed is a function of:The electrical frequency used, typically 60 Hz or 50 Hz.What is meant by voltage regulation?
From Wikipedia, the free encyclopedia. In electrical engineering, particularly power engineering, voltage regulation is a measure of change in the voltage magnitude between the sending and receiving end of a component, such as a transmission or distribution line.Why EMF method is pessimistic?
Ans: The value of voltage regulation estimated by EMF method is always higher or poor than the actual value and hence this method is called pessimistic method. Ans: In EMF method all the MMFs are replaced by emf for voltage regulation where as in MMF method all the emfs are replaced by mmfs for voltage regulation.Why is the synchronous impedance method of estimating voltage regulation is considered as pessimistic method?
Synchronous impedance method gives result which is higher than the original value. That's why it's called the 'pessimistic method'. Armature turn or mmf method gives value which is lower than the original value. It is based on the separation of armature leakage reactance drop and the armature reaction effects.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.Why almost all large size synchronous machines are constructed with rotating field system type?
The following are the principal advantages of the rotating field system type construction of Synchronous machines: The relatively small amount of power, about 2%, required for field system via slip-rings and brushes. Stationary system of conductors can easily be braced to prevent deformation.What is voltage regulation of synchronous generator?
Voltage Regulation of a Synchronous Generator. The Voltage Regulation of a Synchronous Generator is the rise in voltage at the terminals when the load is reduced from full load rated value to zero, speed and field current remaining constant. It depends upon the power factor of the load.What is alternator used for?
Alternators are used in modern automobiles to charge the battery and to power the electrical system when its engine is running. Until the 1960s, automobiles used DC dynamo generators with commutators. With the availability of affordable silicon diode rectifiers, alternators were used instead.What is voltage regulation of an alternator?
The voltage regulation of an alternator is the change of voltage from full load to no load, expressed as a percentage of full-load volts, when the speed and dc field current are held constant. Assume the no-load voltage of an alternator is 250 volts and the full-load voltage is 220 volts.What is salient pole and non salient pole?
In salient pole type of rotor consist of large number of projected poles (salient poles) mounted on a magnetic wheel. Typically number of salient poles is between 4 to 60. Flux distribution is relatively poor than non-salient pole rotor, hence the generated emf waveform is not as good as cylindrical rotor.What is the meaning of salient pole?
Definition of salient pole. : a magnet pole that projects toward the armature of an electric machine — compare consequent pole. 
