# Magnetizing current

by tonyjk
Tags: current, magnetizing
 P: 109 Hello.. I have a question : why when a transformer is loaded on the secondary, in the primary coil there's still the magnetizing current? I know that's the magnetizing current is the current for the no load condition and it's used to establish the flux in the soft iron. But when a load conditon applies there's a bigger current in the primary coil so why there's also a magnetizing current? Thanks
P: 669
 Quote by tonyjk Hello.. I have a question : why when a transformer is loaded on the secondary, in the primary coil there's still the magnetizing current? I know that's the magnetizing current is the current for the no load condition and it's used to establish the flux in the soft iron. But when a load conditon applies there's a bigger current in the primary coil so why there's also a magnetizing current? Thanks
Magnetizing current is present all the time, at no-load or in full load. During No-load whole of the primary current is Magnetizing current but during full Load, magnetizing current is only a fraction of the primary current.
In terms of equation
I_primary = I_magnetizing + I_secondary*K (Full-Load) (K is turns ratio)
However, I_magnetizing and I_secondary will not be in phase and won't add algebraically (needs phasor addition)
 P: 109 Yeah i know this but why there will always be a magnetizing current in load condition? Plus i have another question: the magnetizing inductance is also the inductance of the primary coil no? So why we put it in parallel in the equivalent circuit? And if this inductance is high how come there's an increasing current on load condition? Thanks again
 P: 109 Magnetizing current Can we say that the inductance of the primary coil is the magnetizing inductance and when there's a current in the secondary it produce a counter emf in the Primary coil so that's why the current increase?
 P: 109 So we can say that the equivalence impedance view by the source is the magnetizing impedance and impedance due to the counter emf produced by the secondsry coil in the primary coil? PS: SORRY IM TALKING TOO MUCH