DC Generators
In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralized by all of the following except

Shifting of axis of brushes
Dummy coils
Compensating winding
Interpoles

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DC Generators
When two D.C. generators are running in parallel an equalizer bar is used

To increase the series flux
To increase the generated e.m.f.
To reduce the combined effect of armature reaction of both the machines
So that the two identical machines will pass approximately equal currents to the load

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