Why DC excitation is used for alternators? Why cant it be AC?
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Answer Posted / ketan
when the rotor is rotating via a prime mover.. dc excitation
is given so that constant poles are generated on the rotor
and if ac excitation is given, the poles developed will be
alternating and hence the frequency of the current developed
will be much higher and hence, an ideal Rotating Magnetic
Field(RMF) wont be developed which is generated(for a
3-phase) iff dere's a 120* time phase difference n 120*
space phase diff. is dere. and also due to ac current
flowing dere will be an self induced emf as well
contributing to further losses.
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