why field resistance is higher than armature resistance in dc machines? and why

why field resistance is higher than armature resistance in
dc machines? and why filed resistance is kept at min value
at starting in same time of armature resistance at max value?

Question Posted / ahmed rahman

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why field resistance is higher than armature resistance in dc machines? and why filed resistance is..

Answer / sai

To allow the maximum current through the armature, resistance is kept to very low value. According to ohm's law, V=IR.
As R is very low then current becomes maximum.

Is This Answer Correct ?

21 Yes

10 No

why field resistance is higher than armature resistance in dc machines? and why filed resistance is..

Answer / lokesh luckky

It has two reasons
1) in DC generator to allow large generated currents to output.
2)in motor (torque is proportional to current) so to produce high torque we must allow high currents through winding.

Is This Answer Correct ?

7 Yes

0 No

why field resistance is higher than armature resistance in dc machines? and why filed resistance is..

Answer / abdelbaset

because the consumable power in the field circuit assuming
the same voltage of the main circuit is lower than the
armature circuit. so the excitation current is lower than
armature current so field resistance is greater than
armature resistance

Is This Answer Correct ?

11 Yes

16 No

why field resistance is higher than armature resistance in dc machines? and why filed resistance is..

Answer / binod

field resistance always more than the armature resistance
of a d.c machine(shunt or series or compound).magnetic flux
created by field.to vary generate e.m.f the field
resistance vary from min to max with increase/decrease of
speed.in motor case the speed can be vary by varrying the
field resistance(addition or substraction) with the
required torque.

Is This Answer Correct ?

6 Yes

19 No

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