Can anybody help me ID this atypical power transformer? - Page 1
Forum section: electronics / beginners

author: cdev
author_rank: Super Contributor
timestamp: December 31, 2016, 04:09:05 am
content: At least ten years ago I acquired a semi-atypical power transformer which has sat unused and now I am hoping to ID it and perhaps turn it into a higher voltage/current regulated bench supply.There appear to be two primary windings which can be either parallel or series (they are currently set to parallel) and there are several secondaries 12 volts and looks like high current, 15 volts and 50 volts. Instead of the usual EI core, its slightly different.Its marked "4LP-45336" and so far Ive been unable to find any data on it. I was thinking that maybe somebody here might be able to tell me what the manufacturer was or where to find out what it is or where it is from. It checks out okay on the multimeter, no shorts as far as I can tell.It would be nice to know the current rating. (Is there any way to tell visually?)

author: edpalmer42
author_rank: Super Contributor
timestamp: December 31, 2016, 04:47:04 am
content: Since it was probably custom-made for a piece of equipment, it's unlikely you'll find any info.I use two rules of thumb to figure out transformer ratings. I got them from a catalog of surplus electronics many years ago. I don't remember the company.1) Measure the cross-sectional area of the steel that's inside the coil. Match it to any commercial transformers that have dimensions listed. This gives you the total wattage for the transformer.2) Load down an output until the voltage drops by 10% from its open-circuit value. This gives you the output rating of the coil. Make sure that you're not exceeding the wattage you came up with in step #1, particularly if you're loading up multiple outputs.Remember that load ratings for a transformer aren't an exact science. If you overload one by 10%, it will just run a little hotter. Not usually a problem.

author: cdev
author_rank: Super Contributor
timestamp: December 31, 2016, 04:58:53 am
content: Thank you!The core of this coil is not the usual E shape, its slightly different. the two sides are each wrapped in metal (mu-metal???)Edit: Likely just to keep it from unrolling as each side individually seems to be made out of a metal tape, it looks like it was cut and then reassembled.It is kind of a bit like a balun / binocular core except done with metal laminate material.Uploading an additional pic.Additional edit: It appears to be a double C or ED type power transformer.http://jamestransformer.com/en/transformer/ED_core_transformer.html

author: edpalmer42
author_rank: Super Contributor
timestamp: December 31, 2016, 06:18:14 am
content: At first, I didn't notice that the core is unusual, but now I see that it is! But I don't think that's mu metal. I think that the core is just made of two rolls of steel. Looking closer at the third picture, I can see that the roll goes all the way through rather than just an outside wrap.I don't know if a core like that would be more or less efficient than a standard E-I core. You'd have to measure the transformer parameters to be sure, but that's tedious. I'd run the two tests I mentioned and see if the results make sense. i.e. Is the total wattage based on the core size comparable to the total wattage based on the sum of the power outputs from the voltage drop test? A huge difference between them would be suspicious.