Where can I buy a step down transformer?

Here you go

http://www.saveandcheap.com/index.php?k=step+down+...

I suggest you try some of the local electrical supply houses there were you are at. Maybe they have something you can use or know of a few electrical contractors that may have what you need as well.

I know the Philippines is 60 Hz, (I think) and they use a standard 220 volt single phase like many European countries do. Maybe better for you to buy a U S A made 120/240 volt generator instead of trying to buy a transformer single phase that steps down from 220 to 120. Probably cheaper unless they have something local there for you.

Good Luck :)

Instead of spending money on that kind of junk (it wouldn't be cheap for the kVA you are talking about), just have the power company run another line to the house with a center tap to the pot transformer. Let them transform it. Have you called them to see if 120VAC is available? I sure would. The hertz in the Philippines is 60Hz, so you are fine there. Asking the power company to run a center tap is a lot cheaper than trying to run transformers or converters.

I've never been to the Philippines, so I just don't know, but check one leg of the 220V against ground. I don't think that they use split-phase over there, and it could definitely be polyphasic (wye or delta), but just check it. See if you can't find 120VAC at 60Hz.

If you are in the US, Grainger may have them. Just remember that 50Hz power will make 60Hz time sensitive devices run slower if they rely on line frequency, such as motors that run clocks, refrigerator compressors, etc. A 500va will run about $1200; a 250va unit will run about $750.

Check on the specs for your tools to see what size you'll need. You'll have to buy a plug to adapt the transformer to the power source and loads. Easy and cheap to do yourself.