Shunt-Wound DC Generators
Shunt-Wound DC Generators
When the field winding of a generator is connected in parallel with the generator armature, the generator is called a shunt-wound generator (Figure 1).
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| Figure 1 Shunt-Wound DC Generator |
The excitation current in a shunt-wound generator is dependent upon the output
voltage and the field resistance. Normally, field excitation is maintained
between 0.5 and 5 percent of the total current output of the generator.
The shunt-wound generator, running at a constant speed under varying
load conditions, has a much more stable voltage output than does a
series-wound generator. Some change in output voltage does take place.
This change is caused by the fact that, as the load current increases,
the voltage drop (IaRa) across the armature coil
increases, causing output voltage to decrease. As a result, the current
through the field decreases, reducing the magnetic field and causing
voltage to decrease even more. If load current is much higher than the
design of the generator, the drop in output voltage is severe. For load
current within the design range of the generator, the drop in output
voltage is minimal (Figure2).
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| Figure 2 Output Voltage-vs-Load Current for Shunt-Wound DC Generator |
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