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???

Answer Posted / lakshmi devadas

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 ?    56 Yes 11 No



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