DC Generators
In case of D.C. machine winding, number of commutator segments is equal to

Number of armature conductors
Number of armature coil sides
Number of armature turns
Number of armature coils

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

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

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