innovate.invent

looks like your right

Your best bet is to talk to the HVAC contractors. If you talk to a big company they probably have a contract with a specific brand and they will sell you that one. If you talk to a smaller company they will most likely buy from a wholesaler and probably have shopped around for the one that is going to give them the least amount of trouble as they will guarantee it and have to come back to fix it if it breaks on them. Buy the one with the best "full warranty" as most of them are made in china regardless of brand. oh and I'm sure Danby doesn't make a central air system but they are shit if they do :P

Hey all, so years back I bought this transformer that was supposedly for an arc welder. It came with no documentation or identifying marks what so ever. I keep coming back to this thing trying to learn more from it so that perhaps one day I could start a DIY arc welder project for shits and giggles. I saw similar projects using a microwave transformer but would rather use the real deal. Anyhoo! So heres where I am at: -I have a transformer with three separate coil pairs on the same core leading me to believe that it is a three phase transformer. -Each coil pair (primary/secondary) is tied together making it almost look like a single center tapped coil if it weren't for the significantly different gauges of the windings. From this I can only guess that it is intended to be in a star-star configuration with a common neutral. -I tried to hook the primary of one of the coil pairs up to a 116V supply and it blew the 30A breaker instantly. -I hooked up the same coil in series with a 65W light bulb and got roughly a 0.8V drop across the coil -I then hooked up the same coil again to a 12VAC supply and it cranked out 9.6A before starting to burn out. the best I could calculate is that this thing wants to draw somewhere between 40A and 60A unloaded on a 116V source. Does this mean that the transformer has a nasty internal short or is my lack of understanding of how a transformer works messing me up. Am I having these problems because I am not running all three phases at once? I was told to put a variable resistor in series with the transformer and balance the voltages across both of them to get the impedance but I cant find a ~2ohm 7200W+ variable resistor :P I could just go and hook this thing up and see what happens, but then again I could also just take a sledge hammer to my phase converter. I would rather do a bit of testing first to see why its drawing so much current with an unloaded secondary. Does anyone have any ideas?

Hi all. So I have a 3 phase transformer in a wye wye configuration with the primary and secondary neutrals tied together. It was bought surplus for an arc welder. I was hoping to build the rest of the PWM control circuitry and all that jazz to get a functioning arc welder out of it. My problem is I tried to power up one of the primary coils on the transformer with 120v just to see if it was ok ( I didn't want to attach it straight to my rotary phase changer before testing it a bit) and it blew the breaker instantly. It actually caused the crimp on my overhead service from the street to explode. So before I try that again can anyone tell me what went wrong? I get about an ohm across the primary coil but I am not sure what range it should actually be in. I isolated the primary and secondary coils and there is no continuity between them. Perhaps someone could suggest the next step I should take? I know there are tons of possible reasons for an apparent short. Is it possible that only powering a single phase on the transformer and not all three could cause some kind of crazy inductance surge that I am not aware of? I have yet to grasp the finer points of induction. What kind of resistance should I expect from the primary coil? I would have thought something in the kilo-ohms. The only things I can think to do would be to put a light bulb in series with the transformer and see what happens, and if that doesn't reveal anything then I am gonna have to take it apart and rewind it. :( Which is really not cool, so if there are any better ideas out there please share them. Thanks