 # Voltage regulation of alternator by emf and mmf method pdf

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## Regulation of alternator by emf and mmf method pdf

### Voltage Regulation of Alternator by MMF/Ampere Turn Method

Facebook Twitter. This method is also known as EMF method. Before calculating the voltage regulation we need to calculate the following data. Armature Resistance per phase [R a ]. Open Circuit characteristics which is a graph between open circuit voltage [V o.

Must Read:. The circuit diagram to perform this O. C test and S. C test is given below. The three terminals of the switch are short circuited by an ammeter. The voltmeter is connected between two line terminals to measure o.

For the purpose of excitation, a DC supply is connected field winding. A rheostat is also connected in series with DC supply which is used to vary the field current i.

C supply. So now flux increases, which leads to increase in the induced e. The voltmeter now the actual line value of open circuit voltage. For various values of field currents, voltmeter readings are noted in a table. Now plot a graph between o. The graph obtained is called o.

Position, reducing field current to min. T switch is closed. Now increase the field excitation is increased gradually till full load current is obtained through armature windings. This is observed on the ammeter connected in the armature circuit. Tabulate the values of field current and armature current values obtained. The graph obtained is called S. The S. H curve of a magnetic material. Voltage Regulation of synchronous generator Calculations:.

Zs can be determined from O. C and S. C for any load condition. The value of Ra should be known now. So it can be measured by applying d. So now induced e. Voltage regulation of alternator or synchronous generator is calculated by using the below formula,. Tags Machines. You might like Show more. Post a Comment. ## Welcome to Scribd!

The OC and SC graphs are plotted from the two tests. The synchronous impedance is found from the OC test. The regulation is then determined at different power factors by calculations using vector diagrams. 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. In the MMF method the armature leakage reactance is treated as an additional armature reaction. In both methods the OC and SC test data are utilized.

The voltage regulation of alternator by EMF method involves the EMF quantities of all the armature parameters armature resistance, Armature leakage reactance, armature reaction. The drop due to armature reaction is not considered, because it does not occur due to any of the physical element but due to interaction of armature flux with main flux. Now, the Sum of armature leakage reactance and armature reaction reactance is called synchronous reactance of an alternator X S. In EMF method, the voltage drop due to armature resistance R a and the drop due to synchronous reactance X S is considered, both the drops are emf quantities. This method is also called pessimistic method , because the voltage regulation obtained by this method is more than the actual value. Armature Resistance per phase can be obtained by conducting stator resistance test on the alternator.

Facebook Twitter. This method is also known as EMF method. Before calculating the voltage regulation we need to calculate the following data. Armature Resistance per phase [R a ]. Open Circuit characteristics which is a graph between open circuit voltage [V o. Must Read:. voltage regulation, EMF method, MMF method, modified MMF method, ZPF method, power angle E.M.F. equation of an elementary alternator three phase.

### MMF Method of Voltage Regulation

Facebook Twitter. This MMF method is based on the results of open circuit test and short circuit test on an alternator. For any synchronous generator or alternator, MMF is required, which is a product of field current and turns of the field winding for two separate purposes. It must have an MMF necessary to induce the rated terminal voltage on the open circuit.

The OC and SC graphs are plotted from the two tests. The synchronous impedance is found from the OC test. The regulation is then determined at different power factors by calculations using vector diagrams. The EMF method is also called pessimistic method as the value of regulation obtained is much more than the actual value.

Voltage regulation of an alternator by emf and mmf methods. Voltage regulation of an alternator instrumentation tools. To calculate the voltage regulation by mmf method, the following information is required. How to determine the regulation of an alternator by an asa method and what its difference with respect to other methods. This method of finding voltage regulation considers the opposite view to the synchronous impedance method.

### Regulation of alternator by emf and mmf method pdf

The voltage regulation of alternator by EMF method involves the EMF quantities of all the armature parameters armature resistance, Armature leakage reactance, armature reaction. The drop due to armature reaction is not considered, because it does not occur due to any of the physical element but due to interaction of armature flux with main flux. Now, the Sum of armature leakage reactance and armature reaction reactance is called synchronous reactance of an alternator X S. In EMF method, the voltage drop due to armature resistance R a and the drop due to synchronous reactance X S is considered, both the drops are emf quantities.

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