Forced cooling of toroid transformer

[rikkitikkitavi]

Anybody got any clue about how much more power a toroid transformer can deliver when installed with a fairly good airflow across it?

Mounted on a plate, ie only circumference and top is subjected to free airflow.

The primary will still heat up deep down in the transformer but heat loss by forced convection should improve quite a lot.

I have no idea about thermal conductivity internally from prim-sec-outside.

[sawreyrw]

Forced air cooling can be very effective, but it depends greatly on the surface area and shape and air flow. This is why heat sinks are used. I don't think forced air cooling of a toroid is very practical, and I've never heard of it.

[glennb]

Originally Posted by rikkitikkitavi

Anybody got any clue about how much more power a toroid transformer can deliver when installed with a fairly good airflow across it?
Mounted on a plate, ie only circumference and top is subjected to free airflow.
The primary will still heat up deep down in the transformer but heat loss by forced convection should improve quite a lot.
I have no idea about thermal conductivity internally from prim-sec-outside.

Its a matter of how hot you are willing to let it get (eg. 50 - 60 deg.C surface temperature) and your toleration of increased losses and poorer regulation (due to increase in resistance of copper wire in windings).
For long term reliability and good regulation I would not run a toroid for more than about 75% of its rated load. You are suggesting greater than 100% ?