Transformer found, need help figuring it out - Page 1
Forum section: electronics / beginners

author: tehjrow
author_rank: Contributor
timestamp: June 14, 2015, 06:58:46 pm
content: I just took apart an old UPS and got the transformer. At this point in my electronics hobby I've never used one (I've bought liner PSUs but never used a transformer myself). I can't find any solid info on this transformer since it really doesn't seem to have identifying marks and I can look up. I know the basics of how a transformer works but can't figure out which side is input and which is output and how to wire it up for testing. Any help? (I know i'm a beginner and mains is deadly so I don't want to just randomly hook up things to test)http://imgur.com/a/IsSeO

author: nitro2k01
author_rank: Frequent Contributor
timestamp: June 14, 2015, 07:20:08 pm
content: A rather certain way of identifying the low and high voltage side is by looking at the wire gauge. Thicker wire means higher current, and conversely lower voltage, as the two are inherently inversely proportional on a transformer. (Of course, someone making a transformer could use any wire they wanted for any winding, but this is, logically, the convention.)So the three thin wires on the right (blue-brown-blue) are likely the mains input. The reason for having three wires is so you can switch between 120 V and 230 V. There's no telling which wire is which, but you could trace this out from how the UPS is wired inside.The black-yellow-white triplet on the left side should give you your low voltage. One wire is likely a center tap whereas the other two are likely the same voltage with inverse phase on either wire. But you need to figure this out to be sure.Don't know what the white-black pair on the right side is. Might be a low voltage for some utility application.

author: jeroen79
author_rank: Frequent Contributor
timestamp: June 14, 2015, 08:19:06 pm
content: You can also use a multimeter to measure the resistance between the wires.This can give you clues about which wires are connected to the same winding and what voltage and current they may be made for.An 'OL' indication will mean that the wires belong to different windings.If the transformer came from some device then you can look for a datasheet or servicemanual for that device.It may contain a schematic that explains what is what on the transformer.When you know which wire belongs to which winding then you could empirically determine how the transformer is built.Put a low AC voltage on one winding and then measure the voltage on the other windings.

author: tehjrow
author_rank: Contributor
timestamp: June 14, 2015, 09:50:34 pm
content: Here's what I found out:Left side:All three wires are connected (checked with voltmeter)1ohm resistance between Black and White.5ohm resistance between both Yellow and White and Yellow and BlackRight side:Black and White are connectedBlue, blue and brown are connectedBlack/White is not connected to Blue/Blue/Brown3ohm resistance between OuterBlue and Brown2.5ohm resistance between InnerBlue and BrownThis leads me to believe that Blue/Blue/Brown is my input and Black/White/Yellow is my center tapped output?I have a 9VAC 1Amp output wall wort, will this work for safer testing? I don't yet have a signal generator.

author: nitro2k01
author_rank: Frequent Contributor
timestamp: June 15, 2015, 12:47:50 am
content: Please also confirm the resistance between inner-blue and outer-blue. I would expect it to be about 5.5 ohm (ie roughly the sum of the other brown to either of the blue.) It should be, and this means that outer-blue - inner-blue is the 230 V input and one of the blues- brown is the 120 V input.Now there are multiple things you could do. One is connect it to mains and measure the outputs - of course making sure that none of the other wires short out! Another things you can do is connect the transformer "backwards" with your 9 VAC adapter. (Make sure that what you have is an AC adapter and not DC, also a warning to random internet-wanderers.)If you connect 9 VAC to the black and white onthe left side in the imageie the outer taps of the center taps you should get a high but reasonable voltage on the blacks and blues, which you can measure with your multimeter. Do not connect 9 VAC to the other black-white pair, as this may create an excessively high voltage on the HV side. If you do it right, you can now probe the brown and blues with your multimeter in AC mode, high voltage range if applicable. From this, you can deduce the turns ratio. High voltage will be present on those wires, but this is slightly safer than touching mains voltage since the only possible current path in this case goes between two of the wires, instead of between one of the wires and any grounded object around the lab.If you want to be even safer, you can the 9 VAC to the high voltage side. Then you can probe the other wires which will likely read voltages in the sub 1 V range since you're likely stepping down the voltage by a ratio 1:10 or more.

author: Richard Crowley
author_rank: Super Contributor
timestamp: June 15, 2015, 12:58:46 am
content: The most reliable indication of what windings are which and how they were intended to be used would be to go back to the UPS carcase and trace where the wires went. That should at least tell you which are the primary (mains) winding connections.Trying to guess from simple DC resistance measurements is full of pitfalls for the beginner. And especially for a mains-connected component where the wrong guess could be catastrophic. NOT RECOMMENDED, IME.

author: Cliff Matthews
author_rank: Unknown
timestamp: June 15, 2015, 01:39:21 am
content: Be carefulif you connect this to the mains! Why? The winding with the higher resistance is the outer winding and it's used as a step-up output (normally a ~90 volt square wave). It's likely this was an off-line UPS, so not only is the transformer NOT for mains use, it's also NOT hi-pot tested and insulation inside may NOT be up to mains certification.If you connect this to the line and expect great things - forget it. Yeah play a bit or have fun with a Variac (auto-transformer), but I wouldn't sleep at night with it left on...

author: Deathwish
author_rank: Unknown
timestamp: June 15, 2015, 01:43:55 am
content: Googling the whole sequence of numbers it came up with this.AMP OUTPUT TRANSFORMER Class 130(B) 430-2082 DB ...ebay.catmall.su/items/100333682927714.htmTranslate this page15 Apr 2014 -?AMP OUTPUT TRANSFORMER Class 130(B) 430-2082 DB-EL114-4402A E208707 NER-B82 TUBE ?? ...

author: tehjrow
author_rank: Contributor
timestamp: June 15, 2015, 02:51:26 am
content: I connected 9VAC to Blue/Brown and measured 48-50VAC on White/Black (on the other side). This thing is confusing and I think i'll buy a clearly marked transformer to learn with.

author: Cliff Matthews
author_rank: Unknown
timestamp: June 15, 2015, 11:44:18 am
content: Quote from: tehjrow on June 15, 2015, 02:51:26 amNo! Don't give up mate, this is where the fun begins. Don't turn it on, take it apart! I can't see much from your pictures, but there is likely a shallow weld along 2 sides (where the E-core lamination's meet with I-core). Protect the wires and windings from dust by taping over them and take this bad boy to an auto shop where someone can lightly (and carefully) grind-off those welds with a die grinder. Blow the metal dust off and take it home to pull out the winding spool inside.... (BTW, there's about $5 of useful magnet wire inside)You now have a rather large platform for cool magnetic experiments... Here's some video's to wet the thirst of your inner scientist.1)2)3)

author: Cliff Matthews
author_rank: Unknown
timestamp: June 16, 2015, 04:38:15 pm
content: ..once you carefully get the winding spool out, unwind it without nicking the wires so you can rewind it to do what you want or just use it as a paper weight..

author: fubar.gr
author_rank: Unknown
timestamp: June 16, 2015, 05:31:13 pm
content: You can test the transformer by powering it from mains, using a low wattage incandescent lamp in series to limit current.If you have chosen the correct winding for your local mains voltage, then the lamp shouldn't light up brightly, maybe it won't even light up at all.