[AMRadio] Ferroresonant transformer revisited


Rick Brashear rickbras at airmail.net
Sat May 6 23:09:15 EDT 2006


A while back we had a lengthy discussion about ferroresonant 
transformers.  I received a lot of excellent advice and help.  I have 
finally been able to apply what I learned to a large ferroresonant 
transformer that produces about 24 volts AC and when all is said and 
done the rectified and filtered voltage is about 33 vdc, but drops to an 
average of about 27 vdc when loaded with a 5 a amp load.  The 
transformer itself is capable of 50 - 75 amps.  It's a big one.  It 
seems during the discussions someone made the statement that these 
transformers had a considerable "buzz" and I can verify that, it hums 
like crazy.  It was also said that they run rather warm or even hot.  
That's what I'm curious about.  How hot?   I left it on for about an 
hour with no load at all and I can barely put my hand on the top of the 
core.  Is this normal?  Should I use a fan with it?  It uses a 15 mfd @ 
660 vac capacitor to attain resonance and it is new, so I don't suspect 
a problem there.  It draws approximately .9 amp from the ac line when 
idling, so I don't feel that is excessive.  Do they just run that hot?

Thanks for wading through all of this.

Rick/K5IZ





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