A shunt-excited generator is a machine whose shunt field coil is linked in parallel with the armature terminals, in order that the generator will be self-excited. The principal advantage of this affiliation is that it removes the need for an external supply of excitation.
How is self-excitation achieved?
When a shunt generator is in full swing up, a little voltage is induced in the coil, due to the remaining flux within the poles. This voltage produces a tiny low exciting current IX within the shunt field. The ensuing little mmf acts in a similar direction as the remaining flux, inflicting the flux per pole to extend. The redoubled flux will increase E0 that will increase IX, that will increase the flux still a lot of, that will increase E0 even a lot of, and then forth. This progressive buildup continues till E0 reaches a most worth determined by the sector resistance and also the degree of saturation. Schematic diagram of a shunt generator is shown below. In this a shunt field is one designed to be connected in shunt (alternate term for parallel) with the armature winding.
Controlling the Voltage of a Shunt Generator
It is straightforward to management the induced voltage of a shunt-excited generator. We have a tendency to merely vary the exciting current by suggests that of a resistance connected in series with the shunt field.
The equivalent circuit of a generator is therefore composed of a resistance Ra asynchronous with a voltage E0.
The latter is that the voltage evoked within the revolving conductors. Terminals 1 & 2 are the external armature terminals of the machine, and F1, F2 are the Field winding terminals.