motors and back emf (1 Viewer)

[stef.]

qutoe from a book "an a.c. motor continuously produces a back-emf and so limits itself without the need for a series transistor" meaning a dc motor would need one

but then for both ac and dc motors, the current enters the coil as AC (in ac its just via slip rings and for dc its via split ring commutator) so im quite perplexed...

 

[Captain Gh3y]

AC is continually going through the coil of an AC motor, hence even when it starts up the magnetic field is oscillating 50 times per second.

In a DC motor, when you start it up the field is only changing as the coil turns, which is slow at first. As for the field changing direction, that only happens every 180 degrees, which is also slow at first. DC current enters a motor as DC.

 

[stef.]

wow..that made it so much more clearer..thx