Why DC excitation is used for alternators? Why cant it be AC?
Answer Posted / roy
AC itself produces alternating flux ,so If u gives AC to the
field coil the generator will give transformer action.there
is no need of rotating it.
In case if we rotate the field ,constant field will not be
produced.For every cycle of rotation ,there will continuous
change in the pole wrt 3 wdg of armature,result in irregular
waveform.we cannot get pure sinusoidal 3 phase supply.
so to overcome from above, dc excitation is given so that
constant field strength will be maintained.
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