why do a load on the secondary winding result in increased current in the primary winding
So if the only coupling is flux, is the increased current in the primary due to a badly designed transformer with mutual induction?
Power = V.I
Powerbefore = Vp.Ip = Vs.Is
Powerafter = Vp.(Ip↑) = Vs.(Is↑)
But I'm not exactly sure what it means in practical terms? could you say that "The inductance in the primary changes when load is applied on secondary"?
the core magnetic flux is maximum under no load conditions
I agree with this statement.the core magnetic flux is maximum under no load conditions
If current suddenly flows through the secondary it creates 'new flux' and the direction of this flux 'cancels out' the inductance of the primary.
Indeed it does.Yes, but why is the secondary flux opposing the primary, why couldn't it have the same direction?
Hi,
Indeed it does.
The primary winding is seen as current (power) sink, thus usually the current vector goes into the coil.
The secondary is seen as current (power) source, thus the vector goes out of the coil.
If you see both as equal coils you should use equal vector direction, then they will add.
In any case if you take care of (current_vector_direction x current_value_sign) then it's always correct.
Klaus
Transformer's magnetic flux stays constant, regardless of the load. In other words, transformer's magnetic flux is the same with NO load, with 50% load, or with xx% load.Yes, adding makes sense, it has to increase current -> increased flux
Yes, but why is the secondary flux opposing the primary, why couldn't it have the same direction? Is it for the same reason a solenoid shoots out the hammer in one direction even if it's powered by AC? I.e. the coil doesn't care about flux direction, it's always looking for the lowest inductance?
Transformer's magnetic flux stays constant, regardless of the load. In other words, transformer's magnetic flux is the same with NO load, with 50% load, or with xx% load.
Transformer's magnetic flux stays constant, regardless of the load. In other words, transformer's magnetic flux is the same with NO load, with 50% load, or with xx% load.
true for an ideal transformer
...without winding loss
Incorrect.therefore the magnetic flux do varies according the change in load, therefore the above statement seems incorrect - even would be not true with a permanent magnet inside the core arm (e.g analog meters with needle), once the load on secundary is dissipative.
I perfectly agree with you and your post, but I wanted to keep it simple and by the way, to keep the worst case scenario, which is how the xformer is designed.true for an ideal transformer
...without winding loss.
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