When armature carries a
current, it produces its own flux. Some part of this flux completes its
path through the air around the conductors itself. Such a flux is
called leakage flux. This is shown in the Fig. 1.
 |
| Fig. 1 Armature leakage flux |
Note : This leakage flux makes the armature winding inductive in
nature. So winding possesses a leakage reacatnce, in addition to the
resistance.
So if 'L' is the leakage inductance of the armature winding per phase, then leakage reactance per phase is given by XL
= 2 π f L Ω/ph. The value of leakage reactance is much higher than the
armature resistance. Similar to the d.c. machines, the value of
armature resistance is very very small.
