Explanation: The machine efficiency rises with load. but at a particular load, efficiency is maximum and beyond this load, efficiency diminishes. Also, for both motors and generators, machine efficiency is maximum when variable loss = constant loss. 11. The electromechanical energy conversion devices used in power systems are never operated to deliver maximum power output, because at maximum power output, _____________
A. Efficiency is less than 50%
B. Temperature of the power devices is much more than the specified allowable temperature rise
C. Half of the power input appears as losses
D. Any of the mentioned
Answer:A
Explanation: The machine efficiency rises with load. but at a particular load, efficiency is maximum and beyond this load, efficiency diminishes. Also, for both motors and generators, machine efficiency is maximum when variable loss = constant loss. 11. The electromechanical energy conversion devices used in power systems are never operated to deliver maximum power output, because at maximum power output, _____________
A. Efficiency is less than 50% B. Temperature of the power devices is much more than the specified allowable temperature rise C. Half of the power input appears as losses D. Any of the mentioned
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)?