What to do with a 3kva control transformer?

[PDL]

I've just acquired a toroidal control transformer from the scrap bin at work. The primary is 480/240 and the secondary is 240/120. It is rated at 3 kva and has little bit of heft to it. I cannot find and information on it from the manufacture (Talema), other than the fact that it was built in the United States. The part number on it is a custom part number for my company, so that doesn't really help. Applying 120 volts to any of the windings produces the expected voltages with minimal audible hum.

Any ideas?

[gmphadte]

If u can unwind the secondary and bring out the center tap, then it may be useful for a solid state power amp. Other use is to connect it as an isolation transformer.

Gajanan Phadte

[godfrey]

Are the windings center-tapped, i.e. 0-240-480 primary and 0-120-240 secondary? If so, you could put 120V mains into the 240V primary, and get 60-0-60 from the secondary. It could make a nice supply for a power amp.
Sorry, I meant POWER amp.

[PDL]

Both sides have two separate windings. For instance, if you have 480 and need 120, you hook the primary windings in series and the secondary windings in parallel. However you could also leave the parallel windings independent, each with half of the current rating. They could also be hooked up in series which would create a center tap.

I'm liking the 60-0-60 idea.

[gareth]

And 3kVA divided by the secondary voltage will give you your current rating, thereabouts.

[indianajo]

I use mine for 220-120 drop at the end of a 700' extension cord. I hate chainsaws, their fiddly carburators always being destroyed by this imitation gasoline, the stink of the burned oil, the vile noise, the kickback. Yet I have trees down all over my country property. I use a 120VAC Milwaukee sawzall, a 11" wrecker blade, and plug the first extension cord in the dryer outlet on my trailer. Another 120 VAC nema outlet on the transformer. Voila- works almost every time. If not, I tripped on the cord. I picked up a made in USA electric chainsaw at the charity resale shop for the bigger trees.

[wg_ski]

Originally Posted by indianajo

and plug the first extension cord in the dryer outlet on my trailer. Another 120 VAC nema outlet on the transformer.

*That* deosn't exactly meet code
Neither does plugging all your 10,000 Christmas lights into a big trafo to keep the !@#$^ GFCI's from tripping in the rain.

[indianajo]

If I set my fields on fire I'll let you know.
Sawing a finger off or a slit in your leg with a chainsaw is perfectly legal and a mid-western tradition. Most of my maintenance shop friends have done it. Makes for great stories in the lunch room. I'm such so effete. Just because you need 10 fingers to play Pictures at an Exhibition doesn't mean you shouldn't cut them off like a real man.
Seriously, a 3Kw 60-ct transformer is too big for 4 ohm speakers. My PV1.3K (650 W/ch @ 4 ohm) amp has 95V rails. That thing is 55 lb, way too heavy to be worth much to bar bands. A 3k control transformer weighs nearly that by itself.

[Speedskater]

It would make a nice isolation transformer for your hi-fi system. With 240V from your breaker box and wired as a SDS (Separately Derived System) with 120V receptacles.

See page 39:

http://www.middleatlantic.com/power.htm

[wg_ski]

Originally Posted by indianajo

Seriously, a 3Kw 60-ct transformer is too big for 4 ohm speakers.

Not if your application is hi-fi, where you are expecting to double down into 4 ohms, and again into 2 ohms. If you expect rails that stiff, it can't be too big. Most bar band amps have supplies that drop roughly in half at 2 ohms, and even tour grade drop to around 70% at full whomp unless it's PFC (and very expensive).