Explanation: In practice, devices are operated at a load somewhat less than rated load, at which the efficiency is maximum. 12. For the same rating machines, which of the following statement is correct regarding the efficiency (η)?
A. η of low speed machine > η of high speed machine
B. η of low speed machine < η of high speed machine
C. η of low speed machine = η of high speed machine
D. Any of the mentioned
Answer:A
Explanation: In practice, devices are operated at a load somewhat less than rated load, at which the efficiency is maximum. 12. For the same rating machines, which of the following statement is correct regarding the efficiency (η)?
A. η of low speed machine > η of high speed machine B. η of low speed machine < η of high speed machine C. η of low speed machine = η of high speed machine D. Any of the mentioned
Explanation: The amount of conductor and iron materials required for a machine of given rating is inversely proportional to its speed. Also, more iron and conductor would entail more losses. 13. No load rotational losses in electrical machine consists of _____________