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?
Answers were Sorted based on User's Feedback
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 |
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 |
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 |
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 |
how to identyfy cable sizes?
what do you mean by synchronous speed of a three phase induction motor?
What is signal flow graph?
How to calculate no of Lighning arrestors are required for protecting 50mX 50m*20m cubical building and locations of LA?
What is the difference between a fuse and a breaker?
what are different type of triping equipmen like MCB,MCCB and their differences
3 Answers ABB, Schneider, UPPCL,
we have two generators different capacity on 15 MW and other 6MW at 11 KV , 15 MW gen. bus short level current 40KA,and 6MW short level current 25KA,, length of cable 100MTR between 6 MW from 15MW gen. for bus coupling . kindly tell any one can we use both NGR OR one NGR from any GEN. BOTH NGR has diff. rating. Tariq pakistan
What are the conditions to be satisfied before connecting two DC generators in parallel?
In Plug used in house,Why Earth of the plug more thicker & deeper?
For fixed primary voltage how does secondary terminal voltage of a transformer change if the pf of inductive load is raised from 0.7 to 0.9 with load current remaining fixed ?
what is extra low voltage system
what is the difference between brush & brushless dc motor explain its operation ?
Civil Engineering (5086)
Mechanical Engineering (4456)
Electrical Engineering (16639)
Electronics Communications (3918)
Chemical Engineering (1095)
Aeronautical Engineering (239)
Bio Engineering (96)
Metallurgy (361)
Industrial Engineering (259)
Instrumentation (3014)
Automobile Engineering (332)
Mechatronics Engineering (97)
Marine Engineering (124)
Power Plant Engineering (172)
Textile Engineering (575)
Production Engineering (25)
Satellite Systems Engineering (106)
Engineering AllOther (1379)