| Electronics > Projects, Designs, and Technical Stuff |
| Transformer - strange current waveform and "overheating" ?? |
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| T3sl4co1l:
--- Quote from: max_torque on August 01, 2019, 10:14:16 am ---I had considered saturation from 50hz operation, but it just doesn't feel quite right to me for several reasons: 1) The transformer is sold in the UK by a major distributor - (RS components) surely they would have noticed if everyone returned the units they bought? --- End quote --- You're putting an awful lot more confidence in RS than they deserve, or so it sounds based on others' impressions of them! Tim |
| max_torque:
Swapping it for a different unit shouldn't be an issue, i just want to confirm the root cause. In my pics, if you reverse the current or voltage wave forms (ie the same as swapping L & N around, or changing the direction of current through the current probe) then the current "spike" is leading the voltage by 90deg, which is what you would expect for the position of peak magnetic field strength, so that does tally up. |
| BMK:
--- Quote from: capt bullshot on August 01, 2019, 10:52:03 am ---It's been already said, your current waveform is the typical "saturated core" waveform. The RS page says max. 60Hz operation frequency, but that's just a sign on non-understanding what they're selling. Pretty normal today. --- End quote --- I've used RS for 20 years. Even back in the paper catalogue days you could bet your life on the accuracy of specifications. In the past 3-4 years I have seen a lot of nonsense in specifications. It seems that they don't use technically literate people anymore to parse datasheets into their systems. You cannot trust those search filters. In my opinion they have become the worst offenders of all the vendors I use. You should be able to return the traffo, I've done this many times even after their supposed 14 day cut-off. One thing for sure is they will answer the phone and solve problems like this with little argument. |
| ogden:
--- Quote from: T3sl4co1l on August 01, 2019, 10:58:19 am ---You're putting an awful lot more confidence in RS than they deserve, or so it sounds based on others' impressions of them! --- End quote --- They do not know and do not care - you will use component locally or you will export it as part of product you manufacture. Nobody complains that UK RS components sell various kinds of power plugs that would not fit local mains sockets. The same about transformers. RS components is not your local grocery store and even there buyer is responsible to know what he is buying. --- Quote from: BMK on August 01, 2019, 11:06:59 am ---You should be able to return the traffo --- End quote --- Sure. By customer protection rules/laws they are obligated to handle returns even if mistake is yours. |
| richard.cs:
I would expect it to be marginally better on the 252 V tapping and to not saturate at all on the next one up which is 456 V, though it probably won't be useful for your application either as the secondary voltage will be about 126 V on the 240 V output. I agree the datasheet is poor not putting upper and lower frequencies on it, but as they describe it as a 60 Hz device without giving limits it could legitimately fail at 59 Hz and still meet its specification. It's a transformer, the physics dictates that it has limits to its operating frequency and them not specifying those limits should be a warning sign. I have no idea why RS stocks it in the UK, it's clearly made for American applications with its 60 Hz rating and the options for voltages like 208, 277 and 480 which aren't really used in the rest of the world. I suspect 60 Hz systems probably exist in a few UK factories for imported specialist machinery but it's quite possibly less common even than 400 Hz. If RS are willing to exchange or refund that would probably be your best approach. Otherwise stick it on ebay or something (to paraphrase CQ magazine it might make a fine anchor for a small boat). Take a look at Airlink Transformers for a UK manufacturer of similar transformers in a wall-mount case. I generally find that the data RS pull out of datasheets and onto the product pages is very poor, worse than Farnell and much much worse than Digikey. |
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