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If there is no residual magnetism in the field poles then there would be no flux too induce the initial voltage for self exitation
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What is excitation in generator and 2 methods each?
when the current is passing through the winding then it is called "Excitation". Types of excitation (1)seperately excited generator. (2)self excited generator. self generator is classified into 3 types. 1.shunt generator. 2.series generator. 3.compound generator. compoud generator is again classified into 2 types. 1.short shunt generator. 2.long shunt generator.
What are different methods of excitation of dc generator?
when the current is passing through the winding then it is called "Excitation". Types of excitation (1)seperately excited generator. (2)self excited generator. self generator is classified into 3 types. 1.shunt generator. 2.series generator. 3.compound generator. compoud generator is again classified into 2 types. 1.short shunt generator. 2.long shunt generator.
If a Self excited machine fails to excite what is the reason?
A break in the shunt circuit which is provided with excitation voltage from the armature circuit. Excessively worn armature brushes. This device must be started without any load attached.
Explain the working principle of shunt generator?
A shunt generator is a machine with a rotating set of coils of wire embedded in the iron core in its armature (the spinning part), and a 'commutator' and brushes that carry the current from the (spinning) windings on the armature to the stationary external electrical load. It also has a 'field' winding that creates a stationary magnetic field inside the machine, that the armature coils are spun in. As the windings spin, they cut the stationary field and generate an alternating voltage. As well as providing a moving connection to the coils, the commutator and brushes act like a switch, reversing the connections from the coils to the external circuit each time the waveform changes polarity from positive to negative and vice versa. This creates direct current in the external circuit and load. In a shunt generator, the field windings are connected in parallel with the armature ('shunt' is a common term for 'in parallel') and the field gets its power ('excitation') from the armature - the machine is 'self-excited'. A self-excited generator needs a small 'residual field' in the field's iron core so it can generate a small output from the armature when starting, which is fed to the field, boosting the armature output, which is fed to the field.... and so on, until the field iron core saturates with flux, and the field stops strengthening. Shunt generators are the 'workhorse of the small generator market - they are cheap and simple, have an output voltage that 'droops' a little with increasing load, and most shunt generators can safely be short-circuited - this takes the electrical energy away from the field, and the armature can usually develop only a small output current - not enough to damage it.
Compound generator application?
self ducing
What is excitation in generator and 2 methods each?
when the current is passing through the winding then it is called "Excitation". Types of excitation (1)seperately excited generator. (2)self excited generator. self generator is classified into 3 types. 1.shunt generator. 2.series generator. 3.compound generator. compoud generator is again classified into 2 types. 1.short shunt generator. 2.long shunt generator.
What are different methods of excitation of dc generator?
when the current is passing through the winding then it is called "Excitation". Types of excitation (1)seperately excited generator. (2)self excited generator. self generator is classified into 3 types. 1.shunt generator. 2.series generator. 3.compound generator. compoud generator is again classified into 2 types. 1.short shunt generator. 2.long shunt generator.
Generator how it excite its self?
A generator excites it self due to a high power thyristors feeding to a rotor through slip rings. Once excited it lessons maintenance and operational requirements.
Can you use the separately excited shunt generator machine as self excited generator?
You have a seperately excited generator and then you have a shunt generator which has the field winding in parallel with the armature terminals. In DC machines a separately excited generator could be run as a shunt generator provided the field winding is designed to work on the generated voltage. A separately excited alternator needs a DC supply for the field winding. In car alternators that is taken from the main winding via a rectifier and a voltage regulator.
What happens to the generated voltage of a self excited generator if shunt field resistance is greater than the critical resistance?
it doesn't develop emf ..........
If a Self excited machine fails to excite what is the reason?
A break in the shunt circuit which is provided with excitation voltage from the armature circuit. Excessively worn armature brushes. This device must be started without any load attached.
What Generator has shunt windings and series windings?
A 'compund wound' dc generator has shunt winding and a series winding. The shunt winding has a high resistance, and draws only a small current from the armature, but as it has many turns of wire on it, it generates a strong magnetic field. The series winding has only a few turns of wire on it, and, even though it has a large current in it, its magnetic field is usually less than that of the shunt field. Because of this, the compound generator behaves in most ways like a shunt generator, and is controlled in the same way. As it is self-excited, the compound wound generator requires 'residual flux' to start the generating process. The series winding, if connected to AID the shunt field, can boost the field flux as load comes onto the machine and correct for the normal 'droop' in output voltage as the load increases. If set up properly, this correction makes the generator self-regulating. Because the fields aid each-other, this connection is called 'cumulative compounded'. This type of machine is the workhorse of the larger generator market. If the series field winding is connected so it's field OPPOSES the shunt field, then the output voltage of the generator collapses as the machine is loaded up. This connection is referred to as 'differential compounded', and is only used for arc welding generators - they have a high voltage before the arc is struck; a fairly low voltage during welding operations, and if the rod sticks to the work, they shut the generator down without damaging it.
What is dc separately excited shunt generator?
Either or both can be separately excited. To generate voltage you need a big magnet( the field). Most generators use an electro-magnet. Now the electro-magnet needs a source of power (electricity). We could use the generators own output to excite the field (magnet), this is called self excitation. The problem with self excitation is that we have to wait for the generator to turn and start generating, also to start generating (Building up) there must be some left over magnetism from the last time it was run (called residual magnetism) or not even a little voltage will be generated to start the field current flowing. To solve these problems we could use separately excited. This means we must have a separate source of power to excite the field to produce the magnetism. Sometimes a battery or gasoline driven generator is used to excite the field of a very large generator to get it generating and then we can use some of the generated output to either recharge the battery or switch over to from the battery. In any case we have adjustable control of the generator all the time. This is why most generators are designed to be separately excited. And that is why you car has a voltage regulator. It wakes up the alternator when the engine is started by separately exciting it (the field) with the battery and then regulates the output voltage of the alternator as the engine changes speed with the driver's commands from the gas pedal.
What are the condition of building up a self excited shunt generator?
self excited generator must be started without any external load attached ,an external load will continuously drain off the build up voltage and prevent the generator from reaching its proper operating voltage. also the presence of residual magnetism plays an important role And the field current resistance should be less than critic field circuit resistance
Why terminal voltage of a self excited shunt generator decreases with an increase of load?
When the generator is loaded, flux per pole is reduced due to armature reaction.
What is going to happen when you repeat this experiment on self DC generator?
What is going to happen when you repeat this experiment on self D.C generator?
Explain the working principle of shunt generator?
A shunt generator is a machine with a rotating set of coils of wire embedded in the iron core in its armature (the spinning part), and a 'commutator' and brushes that carry the current from the (spinning) windings on the armature to the stationary external electrical load. It also has a 'field' winding that creates a stationary magnetic field inside the machine, that the armature coils are spun in. As the windings spin, they cut the stationary field and generate an alternating voltage. As well as providing a moving connection to the coils, the commutator and brushes act like a switch, reversing the connections from the coils to the external circuit each time the waveform changes polarity from positive to negative and vice versa. This creates direct current in the external circuit and load. In a shunt generator, the field windings are connected in parallel with the armature ('shunt' is a common term for 'in parallel') and the field gets its power ('excitation') from the armature - the machine is 'self-excited'. A self-excited generator needs a small 'residual field' in the field's iron core so it can generate a small output from the armature when starting, which is fed to the field, boosting the armature output, which is fed to the field.... and so on, until the field iron core saturates with flux, and the field stops strengthening. Shunt generators are the 'workhorse of the small generator market - they are cheap and simple, have an output voltage that 'droops' a little with increasing load, and most shunt generators can safely be short-circuited - this takes the electrical energy away from the field, and the armature can usually develop only a small output current - not enough to damage it.
