Drew
07-03-2020, 10:16 PM
Hi all,
While it seems obvious with a three-phase motor on start up to see a rise in current and then a drop.
I was wondering of the difference between back EMF and inductive impedance.
Both seem to limit current while the motor is turning? Inductive impedance is the overall resistance of the winding while the motor is spinning. If current equals voltage over impedance then it is quite obvious why the amperage drops.
However where is the back EMF in this formula. We seem to be able to do the maths without even worrying about back-emf. Or are they the same thing.
It is hard to find any literature that speaks about impedance and EMF in the same sentence.
They both seem to limit current but when we are using the formula I=v/z where is the back EMF?
So if back EMF and inductive impedance both limit current in a motor what is the difference between them?
While it seems obvious with a three-phase motor on start up to see a rise in current and then a drop.
I was wondering of the difference between back EMF and inductive impedance.
Both seem to limit current while the motor is turning? Inductive impedance is the overall resistance of the winding while the motor is spinning. If current equals voltage over impedance then it is quite obvious why the amperage drops.
However where is the back EMF in this formula. We seem to be able to do the maths without even worrying about back-emf. Or are they the same thing.
It is hard to find any literature that speaks about impedance and EMF in the same sentence.
They both seem to limit current but when we are using the formula I=v/z where is the back EMF?
So if back EMF and inductive impedance both limit current in a motor what is the difference between them?