Transformer at no load
Transformer at no load
(OP)
Hi everyone, I am trying to simulate the current in a transformer when it is at no load, using the software Powerfactory.
I get the Magnetization current, and it is what I was expecting.
But I get confused when I draw the phase current, because as the trafo is at no load... should not be the same the magnetization current and the phase current?
How is possible that the phase current is smaller than the magnetization current?
I don´t understand that.
The picture is the simulation of the normal operation with no load.
The thing is that I don´t understand what exactly is the difference between the magnetization current and the phase current.
I get the Magnetization current, and it is what I was expecting.
But I get confused when I draw the phase current, because as the trafo is at no load... should not be the same the magnetization current and the phase current?
How is possible that the phase current is smaller than the magnetization current?
I don´t understand that.
The picture is the simulation of the normal operation with no load.
The thing is that I don´t understand what exactly is the difference between the magnetization current and the phase current.






RE: Transformer at no load
Thanks everyone...
RE: Transformer at no load
RE: Transformer at no load
It seems to me you neglected primary winding impedance Zp=Rp+jXp.
Rp=primary winding wire resistance Xp=primary winding magnetic field leakage reactance.
Since Io=V/(Zp+Zexc) and Iexc=V/Zexc then Io<Iexc
Zexc=1/(1/Rfe+1/jXm)= Rfe*Xm^2/(Rfe^2+Xm^2)+jRfe^2*Xm/(Rfe^2+Xm^2)=Rexc+jXexc
RE: Transformer at no load
RE: Transformer at no load
RE: Transformer at no load
But I don´t understand your explanation 7anoter4 about that Io<Iexc
I mean that
Io=V/(Zp+Zexc) and Iexc=(V-VZp)/Zexc
and so there is no option for I0 being smaller than Iexct.
--------
Other thing that I would like to comment is the difference between
the phase current of the line at the begining and at the end of it.
I add the image.
How can they have such a difference shape and value?
Have you got PowerFactory?
If you want I could send you the file.dz
Thanks a lot.
RE: Transformer at no load
Actually Io is equal with Iexc if you take into consideration both currents[Ife+jIm]
RE: Transformer at no load
Employing the Flux to Current usual curve we get the magnetic current curve as showing[the green lines]. The red curves have to be if we will take into consideration "two slopes" diagram. It seems to me a third harmonic is involved. This phenomenon occurs in YN transformer connection.
However, usually, iron core saturation will produce triplen harmonics.
RE: Transformer at no load
I ll think about it.
Thanks a lot