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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.
A shunt field (and any series resistor used for adjustment) may be directly connected across the armature terminals in parallel with the load. Where the machine has a series compounding winding, the field may be connected at the armature side (short shunt) or load side (long shunt). The different connections give different voltage regulation characteristics on load.
Current in the field windings of a shunt-wound generator is (approximately) independent of the load current, because currents in parallel branches are independent of each other. Since field current, and therefore field strength, is not affected by load current, the output voltage remains more nearly constant than does the output voltage of the series-wound generator.
There will be armature voltage drop on load, which will be reflected in the voltage applied to the shunt field. The output voltage in a dc shunt-wound generator drops as load current increases because of the voltage drop across the armature resistance increases (E = IR).
In a series-wound generator, output voltage varies directly with load current. In the shunt-wound generator, output voltage varies inversely with load current. A combination of the two types can overcome the disadvantages of both. This combination of windings is called the compound-wound dc generator.
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