Which type of 3 phase converter should I implement? - Page 4
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  1. #61
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    Quote Originally Posted by homer14 View Post
    k. after the fun of searching parts and watching videos, talking to experts, etc. ive decided to order a phase converter panel. when i get it i will tweak it using the fitch model and capacitor tuning. i hope to save some money and speed this up by going this route while also still learning and understanding what is going on in the panel plus fine tuning it as i would have done if building my own.

    stay tuned!
    It doesn't make a great deal of SENSE to purchase a 100% functional unit .. not "just" RPC.. most things ... only to immediately re-engineer it.

    It MAY already BE the classical design we acredit to Fitch Williams. His was cleanly laid out and explained. That is not the same as "new" nor "unique", either one.

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    Unit arrived, Will check it out soon. I need to grab some wire from the store and run it to the location in the shop. Will follow-up after that.

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    the install instructions in the delivered product call for 6 gauge copper to the starter from my single phase end. the Fitch stuff speaks of #10 thhn stranded wire. is fitch only talking about between the starter and the 10hp motor with the #10?

    on this website it looks like #10 thhn can do 40 amps, #8 50 amps, and #6 75 amps. wouldnt i just send two single phases (and a ground) over #10 thhn to this starter as in fitch diagrams or am i misunderstanding the fitch diagrams?

    Ampacity Charts - Cerrowire

  4. #64
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    Quote Originally Posted by homer14 View Post
    the install instructions in the delivered product call for 6 gauge copper to the starter from my single phase end.
    Unless you know something about what the maker of a "store-bought" unit did that they do NOT know?

    Use NO LESS than what they specified.

    I'd be using #4. Because I have it, 5 colours, 100-foot spool, each.

    Copper always costs more next year than it did LAST year, so I tend to buy mine multiple YEARS in advance.

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  6. #65
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    Quote Originally Posted by homer14 View Post
    the install instructions in the delivered product call for 6 gauge copper to the starter from my single phase end. the Fitch stuff speaks of #10 thhn stranded wire. is fitch only talking about between the starter and the 10hp motor with the #10?

    on this website it looks like #10 thhn can do 40 amps, #8 50 amps, and #6 75 amps. wouldnt i just send two single phases (and a ground) over #10 thhn to this starter as in fitch diagrams or am i misunderstanding the fitch diagrams?

    Ampacity Charts - Cerrowire
    Your not reading that chart correctly. For circuits 100A and smaller, you are required to use the 60°C column, unless the terminals at each end are approved for 75°C.

    For circuits over 100A, the 75°C column applies.

    The 90°C column is only used for de-rating purposes, when you have more than three current carrying conductors.

    If your using Romex, (NM-B} the 60° column applies, no matter what the size of the circuit is.

    SAF Ω

    Additional: On the Fitch instructions under power cord, he calls for a #8 AWG minimum protected at 40A.
    Power cord. This unit should have at least an 8-3 SO power cord wired to a 40A 240V plug. Use a matching receptacle on the wall, feed from a 40A-circuit breaker/circuit with #8 wire minimum. Use the same type of cord to connect the idler motor to the control enclosure.

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  8. #66
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    thanks saf and thermite, i was staring at thhn on that chart. ill grab some #6 nm-b.

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    You might want to look at pricing out some #4 AWG aluminum SE cable for a rating of 55A @ 60°C.

    Alu #4 w/4 conductors $1.21 ft. https://www.homedepot.com/p/Southwir...-205001802-_-N

    Your local stock and pricing may vary. 3 conductor Aluminum SE cable would be cheaper, but this box store doesn't list it as a stock item.

    Cu #6 NM-B w/3 conductors $1.26 ft. https://www.homedepot.com/p/Southwir...4402/300312622

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    Quote Originally Posted by SAF View Post
    You might want to look at pricing out some #4 AWG aluminum SE cable for a rating of 55A @ 60°C.

    Alu #4 w/4 conductors $1.21 ft. https://www.homedepot.com/p/Southwir...-205001802-_-N

    Your local stock and pricing may vary. 3 conductor Aluminum SE cable would be cheaper, but this box store doesn't list it as a stock item.

    Cu #6 NM-B w/3 conductors $1.26 ft. https://www.homedepot.com/p/Southwir...4402/300312622
    Shiney wood?

    Fuck NO!

    Leave that to the utility side of a meter. They know how.
    Why did you think it was marked "SE" for Service ENTRANCE"?

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    Quote Originally Posted by SAF View Post
    You might want to look at pricing out some #4 AWG aluminum SE cable for a rating of 55A @ 60°C.

    Alu #4 w/4 conductors $1.21 ft. https://www.homedepot.com/p/Southwir...-205001802-_-N

    Your local stock and pricing may vary. 3 conductor Aluminum SE cable would be cheaper, but this box store doesn't list it as a stock item.
    Shiney wood?

    Fuck NO!

    Leave that to the utility side of a meter. They know how.

    Why did you think it was marked "SE" for Service ENTRANCE?

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    I grabbed some 6/2 copper because it was available and nearby in appropriate length. will wire up as soon as i choke my kids, mow the lawn, put up a hillbilly pool, and get a bit further on a motor rebuild... ill follow up.

    any new cat stories in the meantime? i want a hairless cat.

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    Quote Originally Posted by homer14 View Post
    I grabbed some 6/2 copper because it was available and nearby in appropriate length.
    6-2 "WG" one hopes?
    any new cat stories in the meantime? i want a hairless cat.
    Buy her a no-nick razor, then.

    Your Dentist will be glad he no longer has to use tweezers to remove the..

    ..nevermind...

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    i dont mind the dentist, she can pick them out and/or enjoy not picking them out in the future.

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    Quote Originally Posted by homer14 View Post
    i dont mind the dentist, she can pick them out and/or enjoy not picking them out in the future.
    You could end up teasing a cute MD about her always wanting to go barefoot on the fine carpet she had in her office, indication of a "sensual" nature, and..

    Nevermind.

    So long ago I can't remember how it ended. Might not have even been conscious?

  18. #74
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    is it ok to ground the 3 phase side (idler, load motor) to the ground in the phase converter starter box (which is grounded to the rest of the single phase system)?

    or should i drop a grounding rod into earth near this 3 phase and wire it only to that?

    or do both and ground everything together?

    NOTE: my idler is a WYE. I'll still have just 3 hots and a ground from it in my case. not sure if that matters in my questions.

  19. #75
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    Quote Originally Posted by homer14 View Post
    is it ok to ground the 3 phase side (idler, load motor) to the ground in the phase converter starter box (which is grounded to the rest of the single phase system)?

    or should i drop a grounding rod into earth near this 3 phase and wire it only to that?

    or do both and ground everything together?

    NOTE: my idler is a WYE. I'll still have just 3 hots and a ground from it in my case. not sure if that matters in my questions.
    You are not "grounding" 3-Phase or 1-P side, either one.

    What you are doing is providing a predictably reliable path to "Protective Earth" AKA "ground" for housings, enclosures, machine, and motor FRAMES.

    Rated ground lead back to the tie-point at the Service entrance panel where the local "nest" of one or several driven rods or their subsitute meet sheetmetal (and Neutral) - can meet code.

    Any "local" supplementary ground rod(s) should still be tied to that, anyway.

    That is so any accidental current hitting one, the other, or both does not ALSO give rise to a potential between "presumed" safe PE points.

    At least one water company technician has been electrocuted changing-out a meter yoke where proper practice had failed - and he did not think to check for the possibility.

    My case, the RPC is being moved to share space with the Diesel gen set. I need supplementary rods for the gen set, regardless.

    PE gets a long tie-cable as well. Neutral does NOT. Neutral is a whole 'nuther animal with its OWN rules. Not on your radar, here.

    If a shorter run, your case? A stout PE lead alone may be wiser, If in doubt, double it up just in case one is damaged - and perhaps no extra rod required?

  20. #76
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    Got her hooked up, yeay!

    The docs with the starter state that t1-t3 and t2-t3 voltage with the idler, idle, should be between 5-15 volts higher than t1-t2. this is not the case with mine at the moment. my t2-t3 is actually lower but not by much (6 volts). Should i look to make capacitor adjustments or do these seem reasonable to you guys?

    235v, t1-t2 input from single phase side

    234v, t1-t2 on 3 phase side
    241v, t1-t3 on 3 phase side (+7v from t1-t2)
    228v, t2-t3 on 3 phase side (-6v from t1-t2)

    not that any line is meant to hit a ground, here are the voltages from the 3 phases to a ground anyhow:

    116, t1
    117, t2
    203, t3

    ... i've yet to load the idler as i need to run some more wire now to that location from the converter.

  21. #77
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    Quote Originally Posted by homer14 View Post
    not that any line is meant to hit a ground, here are the voltages from the 3 phases to a ground anyhow:

    116, t1
    117, t2
    203, t3
    Whether intentionally / functionally/accidentally "corner grounded" or just a sensitive low-circuit-load meter reading the equivalent off parasitical coupling, you are looking at what a "corner grounded Delta" produces in the way of a "high leg Delta".

    Delta-connected load motor doesn't see any part of that ground-referred distinction, so "BFD".

    A shock hazard, OTOH, can do.

    Hence my use of the Delta-Wye transformer before I start distributing the power out to the loads.

    So long as you treat ALL electricity as potentially lethal, no foul.

    Even so, "formal" corner-grounding is safer than uncertainty. Also roughly $250 to $700 less-costly than finding space and adding the transformer. And those figures are at used-but-good prices, not NEW prices, plus freight-in for the heavy bastids, new OR used!

    My "other rationale" for the transformer is that I also run a 10 HP Phase-Perfect. Those have a "possible", if not also "probable", degradation mode wherein they can put some right nasty hash onto input and output alike. Several threads on PM cover resulting damage to other goods, and fires - or the potential for them.

    With an environment stuffed chock-full of potentially vulnerable 'puters and appliances, and all the motors pre- "Inverter duty" by scores of years?

    I made the choice to filter BOTH sides of my Phase-Perfect, "just in case".

    Then also use the clean-sine-wave RPC more often than I had originally planned to do. Hence the "upgrade" now dragging on too long.

    RPC don't do that rude hashy-switchy-twitchy EMI-RFI s**t at all, y'see.

    Just a bit of rudeness as to "Total Harmonic Distortion imposed back the UP side of the local grid as may - or may not - annoy the other homes as share the same vault-pig of a utility-mains transformer. Hence the Phase-Perfect.

    Plenty of info out there on all of that. Well worth the read.

    Decisions, decisions, and compromises.

    Life WAS simpler before I put those "backup" second bumfodder dispensers in each loo. As I should have expected?

    BOTH now go dead-empty. At the same moment in time.

    Lybarger's Corollary is inescapable, after all.



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    Guys, thanks for all of the help and guidance. This was and is a fun adventure with some education along the way from other weirdo-freaks like myself. I might follow-up with a future question here or there but I think for the most part its up and running and now is just the load side stuff which in my case is one tool for now.

    If any of you hit up the lower michigan area sometime let me know and I'll get us some beers and we can talk cats!

  23. #79
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    Quote Originally Posted by thermite View Post
    Life WAS simpler before I put those "backup" second bumfodder dispensers in each loo.
    1) sears roebuck
    2) monkey wards

    Do tell, does the door have a half moon, or a star on it?

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    Quote Originally Posted by jim rozen View Post
    1) sears roebuck
    2) monkey wards

    Do tell, does the door have a half moon, or a star on it?
    Elitist! Two different hybrids of corn cob. Silver Queen and Country Gentleman.

    Zero-effort knothole in the bustid board recycled off the old smokehouse. Buckshot holes were from city-girl Mum learning to shoot.

    Dad and his wicked sense of humour having told her to stand with her feet tight together.. then handed her a 12-bore side-by-side NOTORIOUS for "doubling" if yah didn't manage the triggers jest so!

    He did care for her enough to put his arm back of her before she touched-of both barrels so as to make the catch when she was only at about a 30 or 40 degree angle off the vertical.

    Star? Half-moon? We woz too poor to own a jigsaw and too Hillbilly ignorant to know which end of it to light and which to put in yer mout' even if we had been gifted one.

    Folk smoked "tobacco" back in that day. Or chawed of it.

    D'you supppose we have a national drug problem off the back of privy's going out of fashion? Seems to be a linkage over the years.

    Shitty bizness, either way.


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