Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
LScamper wrote:
ken white wrote:
"The volt-second relationship is only valid for continuous current flow during steady state.
If you exceed the kVA rating, with a large impulse current, then my guess is the core will saturate - it is being operated outside of design specifications... "
First, I left out that core saturation is due to not enough magnetizing inductance that keeps the unloaded current down. It has nothing to do with load current.
If you exceed the kVA rating with a large impulse current you may melt the windings but you will not saturate the core if you have enough V-S!
I spent 35+ years in pulse-power. I have designed hundreds of high voltage pulse transformers. V-S is the king, VS=NBA. Current is not involved with core saturation.
Couple the under damped capacitor current, with the transformer in-rush current, and the increased second order voltage effect, and then get back to me about not having a change in flux or saturation.
EDIT: My guess is there will be a DC bias occurring between the half cycles during the transient state since the magnitude of both the primary and secondary voltages will be unbalanced due to the very large, changing, impulse current.
However, you are correct that magnetizing current has a large effect on core saturation, but DC bias and increased voltage does too.
