Answer / 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.

Answer / dharani

because of high currents obtained when it is placed as motor &

Answer / hema

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

Answer / chaitanya

the output of a generator is more and also the input to the generator will be less and so the efficiency will b more

Answer / m.divya sree

machine is to be run as motor under no load condition by requiring less power to be drawn from supply so the efficiency of generator is more than motor

Answer / n.dinakar

Swinburne's test is the most commonly used and simplest method of testing of shunt and compound wound DC machines which have constant flux. In this test the efficiency of the machine at any load is pre-determined. We can run the machine as a motor or as a generator.

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