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.
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.
A shunt generator is a type of DC generator that does not use a permanent magnet. Reducing the speed of the generator will reduce the output, but not the load the generator requires because the currents in the parallel branches are independent.
It does have armature resistance.
swinburne's test on dc shunt machine is to predetermine the efficiency of the dc machine , but it is not accurate it is just like estimation of efficiency of dc shunt machine when it is run as a motor and a generator............................
The theory of converting AC to DC using a 3-phase induction motor and a DC shunt generator involves utilizing the induction motor to mechanically drive the shunt generator. When the induction motor is powered by a three-phase AC supply, it operates and drives the rotor of the connected DC shunt generator. This generator then converts the mechanical energy into electrical energy, producing a DC output. The process allows for efficient conversion of AC to DC, leveraging the motor's mechanical properties and the generator's electrical characteristics.
The difference between a separately excited DC generator and a Shunt DC generator is that for a separately excited Dc generator , the excitation field winding is supplied by an external source different from that supplying the armature while for shunt generator, the excitation field windind is connected in series with the armature and supplied by a single source.
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.
There are two types me dc generator 1 separately excited dc generator 2 self excited dc generator
in a separately excited generator the field coils are excited from a separate source like a dc battery may be or any other small generator. They are self starting generators.
Because the Power Factor is over corrected.
A shunt generator is a method of generating electricity in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current.A direct current (DC) generator, not using a permanent magnet, requires a DC field current. The field may be separately excited by a source of DC, or may be connected to the armature of the generator so that the generator also provides the energy required for the field current.
When reverse the direction of a seperately excited DC generator,only polarities has been reversed,i.e., (+) becomes (-) and (-) become (+).
A shunt generator is a type of DC generator that does not use a permanent magnet. Reducing the speed of the generator will reduce the output, but not the load the generator requires because the currents in the parallel branches are independent.
load test on dc shunt generator is a test to plot the internal and external characteristics of the generator.
Excitation is the phenomenon by which you control the excitation of field winding of a generator. In DC generator field winding is placed on stator and this field winding can be self excited or seperately excited depending upon the type on generator used. AC generators can also be self excited or seperately excited type but field winding is placed on rotor nad armature winding on stator.
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.
as speed increases, induced voltage increases