Which is worse?...core loss or windings loss

[cupoftea]

Hi,
Do you agree, (regarding ferrite transformers) windings loss is better than core loss, because ferrite is a terrible conductor of heat, (its essentially ceramic) and even putting a fan over a hot ferrite core wont cool it down, whereas windings will respond to blown air cooling much better?

As you know, the thermal conductivity of aluminium is 200, whereas for ferrite its 0.35 (W/mm.K)....approx 600 times worse!.........i am baffled that i reverse engineered a 3kW Battery charger once and saw they'd gap padded the top of the PQ4040 to the metal case with a 1cm thick piece of gap pad......i bet they were barely affecting the temperature of that PQ4040? (which was undergoing B++/-0.3T at 100kHz)

....theyd also gap padded , (or tried to), the "windings face" of it to a vertically placed heatsink next to the PQ4040.

 

[KlausST]

Hi,

loss is loss.
1W of winding loss will generate the samme amount of heat (or temperature rise) than 1W of core loss.

If you want to go to temperature limit, then maybe the isolation of the winding melts before the core getd damaged.

Klaus

 

[cupoftea]

Thanks, though as you know, the core can go above curie temperature and then its disaster?

 

[barry]

which is worse, getting run over by a blue car or a red car?

 

[KlausST]

Hi,

sure, then you have an air coil ;-)
Good thing: air doesn´t saturate.

But for sure one should avoid this situation.

Klaus

 

[cupoftea]

which is worse, getting run over by a blue car or a red car?

Thanks, i think the analogy , (due to the horrendously poor thermal qualities of ferrite) is more like getting run over by a "car or a pushbike"...the windings loss being the pushbike.