"Clockman, i might have missed something regarding the toroid mod you did in your pj. I understand the basics about voltage and current matching with windings but could. You explain the benefit? Maybe you were able to increase kw capacity of xfmr that way but dont you need more core too?"
I purchased a PJ 10000w 48vdc, 220vac , 50HZ Inverter. The PJ torroids are woefully inadequate for pulling much power, they get hot, hot, hot, far to quickly, and therefore life expectancy on them is going to be short.
So I stripped for spares, especially the Boards as the whole Inverter was not far off the price of me importing just PJ 15kW boards, the 10kw just requires 2 more capacitors and they are 15kW boards, same layout, size etc.
The torroid cores themselves are usable, that's if you strip all three of them, (I got 3off in my 10kW PJ) and stack them together and wind you own windings, then I think a reasonable toroid could be achieved.
See 'Oztules' ..... http://www.anotherpower.com/board/index.php/topic,1044.0.html?PHPSESSID=h7jd5l4edljl6k4ls18pgfj4i1
And this for working out the Tech stuff on the torroids we make.... .... http://www.anotherpower.com/board/index.php/topic,1117.0.html?PHPSESSID=h7jd5l4edljl6k4ls18pgfj4i1
Reasons for this design of Toroid.
Why don’t we just buy a toroid transformer ready made? Ahh, that’s where this toroid design wins hands down.
1. We double, treble, quadruple, stack the cores. Keeps the copper loss down, but increases the core mass so its cooler and can handle more. But, now’s here the sting, the core centre is now too small, because of its double stacked height, for a normal commercial toroid manufacturing winding machine to get in. So this design has to be hand wound.
2. After each secondary winding, we Epoxy the winding before putting the next layer of Mylar insulating tape on. Its not to heavy coating, but this stops the windings from vibrating, rubbing together and eventually failing, it also helps with cooling.
3. As this design is hand wound, the Primary small number of turns can be the full size big diameter cable. This also helps significantly with keeping the toroid cool as this winding is open, and air flow can easily circulate around and through the toroid.