- #1

gorlyu

- 8

- 1

I have been battling this topic for one year now. Frequenctly revisiting it and trying to find a clear answer on the internet and in but without finding it. Could be that my knowledge level is too low. However, I'll give it a shot here.

So what I have been learned is that during no-load of the transformer with high permeability cores there is perfect coupling from primary to secondary. I .e. the voltage ratio equals the turn ratio. When loading the transformer the secondary will produce an mmf that is balanced by the primary mmf with a small deviation in terms of magnetization current on the primary.

However, there is a leakage flux making up the series impedance. This leakage flux is imperfect coupling during load from primary to secondary and as I understand it, secondary to primary. I.e. both coils have their own associated leakage flux and therefore series impedance.

What bothers me is that this leakage flux is constituted in terms of a voltage drop or rise, and not loss of current. I know I'm wrong but I cannot understand why. My thinking is as follows:

- Let's say you produce a certain mmf in the primary coil but part of that mmf is the leakage flux, consequently the secondary coil cannot balance that leakage flux (because it is not linking the secondary) and hence there would an imbalance in terms of mmf.

There is something fundamental I'm missing here and I would appreciate clearing this out.Gorlyu

P.s.

A similar situation is for current transformers. They are designed for a certain current ratio between primary and secondary. That current ratio will not change when you increase the distance between the primary and CT-core? So there is no difference in that ratio if you have 3 cm diameter of a CT or 300 cm? Given that you introduce no additional disturbances.