engineering recuitment NMDC Junior Officer (Trainee) Mock Test 2024 Electrical Machines DC Motor DC Motor Principle
Two series motors are mechanically coupled. One machine is run as motor and the other as generator. The iron and friction losses of the machines will be identical when
1
Their speeds are identical
2
Their speeds and excitations are identical
3
Their speeds are equal and back emfs are half the supply voltage
4
Their ratings and armature sizes are identical