Hi, I was just reading Mutual inductance and basic operation
http://www.allaboutcircuits.com/vol_2/chpt_9/1.html
and what got me a little confused is this part
"Magneto-motive force is produced any time electrons move through a wire. Usually, this mmf is accompanied by magnetic flux, in accordance with the mmf=ΦR “magnetic Ohm's Law” equation. In this case, though, additional flux is not permitted, so the only way the secondary coil's mmf may exist is if a counteracting mmf is generated by the primary coil, of equal magnitude and opposite phase. Indeed, this is what happens, an alternating current forming in the primary coil -- 180' out of phase with the secondary coil's current -- to generate this counteracting mmf and prevent additional core flux. Polarity marks and current direction arrows have been added to the illustration to clarify phase relations: (Figure below) "
also
"If you find this process a bit confusing, do not worry. Transformer dynamics is a complex subject. What is important to understand is this: when an AC voltage is applied to the primary coil, it creates a magnetic flux in the core, which induces AC voltage in the secondary coil in-phase with the source voltage. Any current drawn through the secondary coil to power a load induces a corresponding current in the primary coil, drawing current from the source. "
What get's me a little confused is the part about the secondary current inducing a current 180' out phase with the secondary.
You see I have always thought the way it works is as follows.
The primary current induces voltage in secondary, Secondary voltage causes current, current is out of phase with primary current by 180', the magnetic flux in the core decreases, primary current decreases and field collapses back inducing back-emf but because the secondary decreased flux, less voltage is induced in primary causing higher current flow.
I always thought the action of the secondary affecting primary current was delayed until the primary field collapsed back inducing voltage. IS that wrong?
If what i read is true then does that mean the primary actually has two currents running through it?
http://www.allaboutcircuits.com/vol_2/chpt_9/1.html
and what got me a little confused is this part
"Magneto-motive force is produced any time electrons move through a wire. Usually, this mmf is accompanied by magnetic flux, in accordance with the mmf=ΦR “magnetic Ohm's Law” equation. In this case, though, additional flux is not permitted, so the only way the secondary coil's mmf may exist is if a counteracting mmf is generated by the primary coil, of equal magnitude and opposite phase. Indeed, this is what happens, an alternating current forming in the primary coil -- 180' out of phase with the secondary coil's current -- to generate this counteracting mmf and prevent additional core flux. Polarity marks and current direction arrows have been added to the illustration to clarify phase relations: (Figure below) "
also
"If you find this process a bit confusing, do not worry. Transformer dynamics is a complex subject. What is important to understand is this: when an AC voltage is applied to the primary coil, it creates a magnetic flux in the core, which induces AC voltage in the secondary coil in-phase with the source voltage. Any current drawn through the secondary coil to power a load induces a corresponding current in the primary coil, drawing current from the source. "
What get's me a little confused is the part about the secondary current inducing a current 180' out phase with the secondary.
You see I have always thought the way it works is as follows.
The primary current induces voltage in secondary, Secondary voltage causes current, current is out of phase with primary current by 180', the magnetic flux in the core decreases, primary current decreases and field collapses back inducing back-emf but because the secondary decreased flux, less voltage is induced in primary causing higher current flow.
I always thought the action of the secondary affecting primary current was delayed until the primary field collapsed back inducing voltage. IS that wrong?
If what i read is true then does that mean the primary actually has two currents running through it?