Introduction to Electrical Power and Power Electronics

39

2

Common Aspects of

Power Equipment

All electrical machines have two sets of coils; one set (field coil in generator

and motor and primary coil in transformer) produces the working magnetic flux

φ, and the other set (armature coil in generator and motor and secondary coil

in transformer) reacts to flux φ and produces an electromotive force (voltage)

in the generator and transformer and a mechanical force (torque) in the motor.

Both sets of coils are embedded in magnetic steel to produce the required flux

with a minimum magnetizing (field excitation) current. The electromagnetic

interaction between two sets of coils is governed by the follo