Answer / velayutham

Hopkinsons test is also referred as the regenerativr or
Back-to-Back test. It means two identical machines are
connected parallely, where as the first machine gets exited
from the source so, it acts as a motor and is mechanically
coupled with next machine and makes it to run as a
generator. The electrical output power from the generator
(second machine) is fed to the motor(First machine) and
vice-versa. But due to the losses in this machines the
output from the generator is not sufficient to run the
motor, hence the losses are supplied by the extra motor
which is belt connected to generator motor set.

Answer / hitesh ambaliya

hopkinson's test is also known as regenerative test.There
are three methods of test of dc machine.1st is direct method
, 2nd is indirect and 3rd is regenerative .here in
hopkinson's test two identical machines are used. identical
means same ratings.one machine act as motor and second as
generator. both machines are mechanically coupled.now when
supply is given to the motor there is losses and output
given to the generator. so it produce power which is given
to the supply.so it is back to back test.so her less power
supply is required. approximately 3.7 v.the advantages of
this method is that less power is require. 2nd is this test
performs on full load test thus we can find temprture rise
on load.disadvantage of this test is that to get two
identical machines.

Answer / half1951wit0202

Hopkinsons test is also referred as the "Regenerative" or
"Back-to-Back" test. Two identical DC machines are
connected parallely, where as the first machine gets supply
from the DC power source, and acts as a motor and is in turn mechanically coupled to the next machine and makes it to run as a generator. The electrical output power from the generator(second machine) is fed to the motor(First machine) and vice-versa. But due to the losses in these two machines the output from the generator and the motors are not sufficient to run each other, hence the losses are to be compensated externally. In the original Hopkinsons' tests this external power supply was made mechanically by an additional motor coupled through belt-drive. However , in the modified Hopkinson's tests , the external power is supplied electrically from the DC power source.

Answer / hirdesh

This test also known as back to back test.it is requires to
machines ,which must be identical.These machines are
mechanically coupled

Answer / abhi

Hopkinson's test is another useful method of testing the efficiency of a dc machine. It is a full load test and it requires two identical machines which are coupled to each other. One of these two machines is operated as a generator to supply the mechanical power to the motor and the other is operated as a motor to drive the generator. For this process of back to back driving the motor and the generator, Hopkinson's test is also called back-to-back test or regenerative test.
If there are no losses in the machine, then no external power supply would have needed. But due to the drop in the generator output voltage we need an extra voltage source to supply the proper input voltage to the motor. Hence, the power drawn from the external supply is therefore used to overcome the internal losses of the motor-generator set.

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