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Thread: capacitor replacement - PhasePerfect converters

  1. #1
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    capacitor replacement - PhasePerfect converters

    has anyone replaced the caps in their PP units with "stock" 40uF capacitors that they source from a place other than PhasePerfect? i'm seriously considering it, given that they are standard capacitors... and *significantly* cheaper than purchased through PP. anyone do this?

    thanks,

    -- dz

  2. #2
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    Just make sure the voltage is as high or higher. Easy enough if the terminals are the same type and sex or do they solder on?
    Bill D

  3. #3
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    As Bill said, check capacitance and voltage, then go aheadů. Tegards, Rod

  4. #4
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    I'll add a word of caution from my EE days. Once you enter the realm of capacitors used in electronic applications, meaning other than AC caps used for motor starting, there are factors beyond capacitance and voltage that can be important, such as maximum ripple current and effective series resistance. These things are likely to be important in a high power switching power supply like the PP digital convertors. If the caps are marked with a manufacturer and part no, and you can source them from alternate suppliers, full speed ahead. If all you know is the capacitance and voltage ratings, more caution is advised.
    --Certainty is the refuge of a small mind--

  5. #5
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    i appreciate all of the feedback, and certainly fully understand what's been discussed. the caps in the PP are simple - they are 370V, 40uF +/-6% round capacitors. they are readily available. the only difference between "stock" caps with the same specs and the ones in the machine is the resistor soldered across the leads for bleed-off, and the screw terminals vs. spade terminals. i can certainly solder on a resistor, and somehow figure out how to "convert" the spades to accept the screws.

    surpluscenter.com has literally the exact capacitors that ship from PP, for **$5** each. same brand, same specs. but, they were manufactured in 2012. best i can tell, caps have a shelf life (even if unused), so that's out. grainger has caps of the same spec for ~$13 each, but they are made in china, something i generally try to avoid (when possible). i would spend a little more for higher quality capacitors (if such a thing even exists), but PP wants $350 for 8 ($44 each). it seems quite hard to justify that cost when they are off-the-shelf items.

    bottom line, i'm not yet sure what approach to take. i appreciate any and all guidance.

    here are the surpluscenter.com caps: https://www.surpluscenter.com/Electr...SN-22-1338.axd

  6. #6
    only replaced caps once on one of two rotos and that had well over 30 years use on it. I read here before that electronic brakes will take out capacitors early. Only have one machine a radial with a Short Stop. It will be taken off because of what I read here. Not a big deal but I dont need electronic breaking on one machine when others dont have it.

  7. #7
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    I've been in electronics my whole professional life, covering design, service an repair, - AOT...
    If you buy your parts from reputable dealers, you should be OK... in the US you have Mouser, Digikey, Allied - and several more... for capacitors and semiconductors, I'd stay away from Ebay, - at least "oriental" vendors.... Even if some of them actually are OK and serious about their bussiness, there are still a lot and way too much of fakes around...
    Pay attention to specs and tolerances, and for power electronics, make sure you get the same or better temp. range....

  8. #8
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    I would get the cheap old ones and reform them before use. Seems cheap enough to try.
    Bill D

    https://landandmaritimeapps.dla.mil/...=MIL-HDBK-1131

  9. #9
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    Quote Originally Posted by David Zaret View Post
    same brand, same specs. but, they were manufactured in 2012. best i can tell, caps have a shelf life (even if unused), so that's out.

    The shelf-life of 10 years really has to do with electrolytic capacitors. For film caps, the shelf life is much longer (film caps are pretty much indestructible except for defects and extreme voltage/temperature). I cannot find any detail on what kind of cap that CSC capacitor is from the surplus site. If it's an electrolytic, I would avoid it as all costs, lol.

    If you are okay with a 10,000 hour runtime at 85 degrees Celsius (that's 185 Farenheit), you can get away with some $12-20 caps. If the operating temperature is less and voltage is less than what's rated on the cap, the actual runtime can be 3-5 times longer. Take a look at this list:

    https://www.mouser.com/c/passive-com...%20Rating%20AC

    They are all film caps. Unless you are a production shop running 8 hours a day for 5-10 years, it is not likely you will need the 60,000 hours caps.

    If PP is asking $44 each, they are probably 60,000 hour film caps (that is 60,000 hours of runtime at 85 degrees).

    10,000 hours is 8 hours a day (including weekend) for 3-1/2 years.

  10. #10
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    Oh, one more thought. If you are considering getting one of those from Mouser, pay specific attention to the physical size. That list is all 40MFD 470V caps, but some are physically larger than others. You need to make sure you can fit/mount them in the existing space.
    Last edited by Aaron Inami; 07-01-2022 at 5:44 PM.

  11. #11
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    aaron -- the CSC caps you see on the surpluscenter site are indeed what came out of the phaseperfect unit - that's what they are selling. they are just marking them up, dramatically. thanks for the info on the film vs. electrolytic, this makes sense, and i guess i need to figure out what those CSC caps are... i'm going to replace them every year, so the x0,000 hour life is irrelevant.





    Quote Originally Posted by Aaron Inami View Post
    The shelf-life of 10 years really has to do with electrolytic capacitors. For film caps, the shelf life is much longer (film caps are pretty much indestructible except for defects and extreme voltage/temperature). I cannot find any detail on what kind of cap that CSC capacitor is from the surplus site. If it's an electrolytic, I would avoid it as all costs, lol.

    If you are okay with a 10,000 hour runtime at 85 degrees Celsius (that's 185 Farenheit), you can get away with some $12-20 caps. If the operating temperature is less and voltage is less than what's rated on the cap, the actual runtime can be 3-5 times longer. Take a look at this list:

    https://www.mouser.com/c/passive-com...%20Rating%20AC

    They are all film caps. Unless you are a production shop running 8 hours a day for 5-10 years, it is not likely you will need the 60,000 hours caps.

    If PP is asking $44 each, they are probably 60,000 hour film caps (that is 60,000 hours of runtime at 85 degrees).

    10,000 hours is 8 hours a day (including weekend) for 3-1/2 years.

  12. #12
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    If you are planning to replace every year, take a look at this one:

    https://www.mouser.com/ProductDetail...oMDcS4Ng%3D%3D

    It's a Class B (10,000 hours at 420VAC or 3,000 hours at 470VAC). The size is 45mm x 98mm. It is exactly the same width as your CSC and only 3 mm longer. At $10.76 each, it's very affordable. Mouser has 275 in stock. Kemet is a very good manufacturer for industrial type capacitors.

  13. #13
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    Why replace yearly? Is this for aircraft or healthcare use?
    Bill D

  14. #14
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    my PP is the heart of my shop. i have multiple CNC-controlled, 3ph machines that depend on it, and stress it. i do this professionally, and it's well worth the insurance factor to replace them and ensure the PP is healthy.

    the last time i replaced the caps was august, 2020. over the past month or so, i've seen the PP shut off periodically when i start my shaper with an "over voltage" error. it's getting more frequent - today it shut off on me three times during an 8 hour session. the shaper has a very large motor, and the inductive breaking really stresses the caps. PhasePerfect tells me that the health of those capacitors is the main culprit in the symptoms i see, and i cannot be down.

    aaron i'll check those out - thanks.

    -- -dz

  15. #15
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    That link you provided to the CSC capacitor has a picture of the capacitor and label. If you zoom on the label, you will see "A COMBUSTIBLE FLUID" which leads me to believe these are electrolytic caps. Film caps are solid material and do not contain any fluid. The Electrolytic caps do contain a fluid that can leak over time and dry out from heat exposure. They can also boil from extreme heat/usage which causes the case of the capacitor to bulge out (you may have seen this sometime in your life). Also, on the CSC caps it states "70 C" which stands for 70 degrees Celsius. Not quite as good as the 85 degree standard on the Kemet. No idea what this actually means on the label, but I have to assume the max rated temperature.

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