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Question
```In Swinburne's Test on D.C.machines, why the efficiency  is
more when the machine runs as generator than when it runs as
motor???```
Question Submitted By :: Ranga2k8
I also faced this Question!!     Rank Answer Posted By

Re: In Swinburne's Test on D.C.machines, why the efficiency is more when the machine runs as generator than when it runs as motor???
# 1
because of high currents obtained when it is placed as motor &
 Is This Answer Correct ? 36 Yes 22 No
Dharani

Re: In Swinburne's Test on D.C.machines, why the efficiency is more when the machine runs as generator than when it runs as motor???
# 2
The total loss Pl= constant loss(Pk) + variable loss(Pv)
for any DC machine.
For generator, since Ia=Il+If, the efficiency = 1-Pl/
(VtIl+Pl)
For motor, Ia=Il-If , the efficiency =1-Pl/VtIf.

Its obvious that the efficiency value for generator will be
higher than motor, since Pl is not a negligible value.

 Is This Answer Correct ? 23 Yes 4 No

Re: In Swinburne's Test on D.C.machines, why the efficiency is more when the machine runs as generator than when it runs as motor???
# 3
the output of a generator is more and also the input to the generator will be less and so the efficiency will b more
 Is This Answer Correct ? 12 Yes 7 No
Chaitanya

Re: In Swinburne's Test on D.C.machines, why the efficiency is more when the machine runs as generator than when it runs as motor???
# 4
in motor the supply voltage isopposed by the back emf .soit
draws more current to run the load
but in generator the whole generated emf supplied to the load

 Is This Answer Correct ? 14 Yes 4 No
Hema

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