Hopkinss test in DC motor is conducted at ?
A. No load.
B. Low load.
C. Full load.
D. None of these.
Show Answer
Answer: C
Share your understanding of this question with the correct explanation.
The answer is C. Full load.
Hopkinson’s test is a method of testing the efficiency of DC machines. It is conducted by connecting two identical DC machines in parallel, one acting as a motor and the other as a generator. The motor is loaded to full load and the generator is unloaded. The power input to the motor is measured and the power output of the generator is also measured. The efficiency of the motor is then calculated as the ratio of the power output to the power input.
Hopkinson’s test is conducted at full load because this is the condition under which the motor and generator are most likely to operate in practice. The test results are therefore more representative of the actual performance of the motor under load conditions.
The test can also be conducted at no load or low load, but the results will not be as accurate. This is because the losses in the motor and generator are not constant at all load conditions. The losses are higher at full load than at no load or low load. Therefore, the efficiency of the motor will be lower at full load than at no load or low load.
Here are some of the advantages of conducting Hopkinson’s test at full load:
- The results are more representative of the actual performance of the motor under load conditions.
- The test is more accurate.
- The test can be used to determine the efficiency of the motor at different load conditions.
Here are some of the disadvantages of conducting Hopkinson’s test at full load:
- The test requires two identical DC machines.
- The test requires a large amount of power.
- The test can be dangerous if the machines are not properly insulated.