# are ideal transformer with non-unity coupling coefficient same as non-ideal transform

Thread Starter

#### zero_coke

Joined Apr 22, 2009
294
I'm just wondering if by modeling an ideal transformer with non-unity coupling coefficient is sufficient to model a non-ideal transformer. Is it possible to do this?

#### tshuck

Joined Oct 18, 2012
3,534
I'm just wondering if by modeling an ideal transformer with non-unity coupling coefficient is sufficient to model a non-ideal transformer. Is it possible to do this?
Probably not, the non-deal transformer has capacitance and resistance in its windings, where the ideal transformer won't. The non-unity coupling coefficient should only affect the inductance of the transformer...

#### #12

Joined Nov 30, 2010
18,222
#12 agrees.

Thread Starter

#### zero_coke

Joined Apr 22, 2009
294
But the resistance of my non-ideal transformer (two air core coils) is so small I can almost neglect it (0.2 ohms). And it doesn't have a core so there are no core losses. I'm just trying to model my air-core transformer with negligible resistance here, now in this case, can I do this with the ideal transformer having non-unity coupling coefficient?

#### Ron H

Joined Apr 14, 2005
7,014
But the resistance of my non-ideal transformer (two air core coils) is so small I can almost neglect it (0.2 ohms). And it doesn't have a core so there are no core losses. I'm just trying to model my air-core transformer with negligible resistance here, now in this case, can I do this with the ideal transformer having non-unity coupling coefficient?
An air core coil has low resistance AND low inductance, so the Q is affected by the resistance. Unfortunately though, skin effect probably affects it even more. You could calculate skin effect resistance, but I don't know if that would give you an accurate estimation of Q.

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