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APC UPS, now with aluminum wire

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damn it sounds like something happened to that wire it should not be so fragile. Its fragile but you should be able to loop it

does it get oxidized and stiff over time that makes it unable to bend?

Aluminium work hardens a lot more than copper does, and yes with time you get intermetallic corrosion as well, which creates thin layers of insulating oxide through the cable. Thicker cables this takes a lot longer. You will find the reason the wire is copper coated before insulation in motors and transformers is to both allow it to be soldered, and also to provide a barrier to oxygen penetrating, though I have seen wire down to 36SWG be copper coated aluminium now, before it was only things that were 18SWG or lower that were CCA, but now you see very thin CCA wire, especially in things like network cable, where you get 7 strands in 22AWG wire in the sheath, and those do sort of hold up, though they do not solder at all well, and will hold up in a crimp for a while. Gel filled Scotchloks though do work well on them.

its interesting because I heard that with air plane parts if they are anodized they will fracture after enough fatigue rather then just bending (reason for alodine and paint instead of anodizing airplanes). Its kind of like wood in that regard when it gets old it seems like. Not sure if the natural oxidation would ever compare to the anodizing process though for that effect to occur. So its not like the hard surface just cracks off like I would think it does but it makes the material crack suddenly.

kind of wonder if you made a bare aluminum plane that was exposed to the air for long enough would it turn brittle like that. I wonder how many years it would take.

This seems to be a fairly common issue with these BR1500MS pure sine-wave models.  They are probably one of the main offerings by APC is the ~$200USD price range.  My work has a few APC UPSs to power some of our equipment that we cannot afford to lose data on.  We had a BR1500MS in operation for ~4 years (probably a little longer than the warranty) and it all the sudden started smoking and beeping.  I took it out of service (I am the lab equipment engineer for my work) and it sat in my junk pile for a while.  During down time I would take a stab at fixing it, but it just kept blowing the inverter MOSFETs.  I had suspected the transformer, but it passed continutity test and hooking up to my variac, it was able to deliver the correct voltage.  Then I saw this video from Dr. Carlson's lab.  I took a look at the transformer tap connections and mine looked pretty sturdy unlike his.  I ended up acquiring a HI-POT tester for a different project and I hooked up the transformer to it - it failed immediately!! Also, grabbed a transformer on eBay from a similar model and now the UPS works just fine!  He's right though - typically the transformer should be one of the most robust components in a unit like this.  So it makes troubleshooting one of these when they throw errors (like F02, F04, or F06) a real pain in the ass if you are unaware.  Here's a video I posted on youtube HI-POT testing two different APC transformers 1) the BR1500MS and 2) BR1500G

Another follow-up to this topic.  My work got in a couple of these APC UPS BR1000MS models.  They are the pure sine-wave model also called the UPS back-up Pro.  It is one APC's most well known offerings and it's likely one of the first UPSs to pop up on Amazon if you search 'UPS'.  They are the exact same type that Dr. Carlson shows in his video.  Anyway, I decided to HI-POT test the large AVR/inverter transformer when it is brand new.  It fails miserably!! I can barely get it up to ~400-500VAC.  This is terrible when you consider the formula for HI-POT testing which is Vt = (2Vw + 1000) where Vt = test voltage and Vw = working voltage.  The max working voltage for this transformer is ~120VAC.  So test voltage for this transformer should be ~1200VAC and it should be able to withstand that for a few secs.  It cannot get even close to that!! And again, this is brand new right out of the box!! Here's a video I did showing the test below.

Now I've also tested the APC UPS BR1500G AVR transformers and they seem to be built much better.  They will pass a HI-POT test at ~1200VAC.  So if you ever have one of these BR MS models and want to fix it, you can grab one of these BR1500G transformers on eBay (I've seen them go for $20 used).  You'll just need to replace the primary side lead wires to a thicker gauge and of course change the terminals to ring or fork style.  I've done this repair on my own BR MS models and it works great!!  If you have one of these BR MS models I would recommend doing this because this transformer will likely fail at some point and when it does (due to internal breakdown/shorting btw windings) it will draw massive amount of current and blow one or more of the inverter MOSFETs.  This can happen in a very violent manner and could cause a fire.

Also, I know Dr. Carlson complains about the transformer winding being aluminum, but a lot of transformers use aluminum windings and they have no problems whatsoever.  These are likely just made poorly with inefficient insulation.  I'll have to cut one open to see how it looks inside!  Hope this helps someone!


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