Two series motors are mechanically coupled. One machine is running as a motor and the other as a generator. The iron and friction losses of the machines will be identical when
A. their speeds are identical.
B. their speeds and excitations are identical.
C. their speeds are equal but back emfs are half the supply voltages.
D. their ratings and armature sizes are identical.
Answer:B
Two series motors are mechanically coupled. One machine is running as a motor and the other as a generator. The iron and friction losses of the machines will be identical when
A. their speeds are identical. B. their speeds and excitations are identical. C. their speeds are equal but back emfs are half the supply voltages. D. their ratings and armature sizes are identical.