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3 phase charger to single phase

Discussion in 'ELECTRICAL ISSUES - POWER YOUR MACHINES & SHOP' started by Mikebr5, Aug 9, 2017.

  1. Mikebr5

    Mikebr5 United States Active Member Active Member

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    While I wait for parts for my rotary phase converter to arrive I figured out that I need to use a charger sooner than the fix will take place. Cash is tight and I am not eager to go out and buy a single phase charger when it looks like this one will do with simple mods.
    Here is the schematic.
    20170808_074526.jpg
    It looks like 2 legs are used for the DC power... So I am not worried about rectifier harmonics. (maybe I should be though? 120 degrees versus 180 degrees?)
    I already switched it to 240V like this in orange:
    20170808_074526a.jpg The yellow is my mystery - what effect will switching to single phase have on the 3rd leg windings?
    There are only 2 limbs on the transformer- the 3rd leg shares a limb with the 2nd leg.
    The only times that I have monkeyed with going from 3 phase to 1 phase in a transformer setting were with individual (stand-alone) transformers... separated by air. So I am concerned about releasing the magic smoke if there is a 120 degree "timing" issue with the shared core.
    20170808_083342.jpg Sorry for all the dust... This is before I cleaned it.
    In the pic it is still jumpered for 480V as I was using it earlier that way.
    My plan was to remove L3, and stack 3 wires on the load side of the contactor so L1 and L2 supplied each winding of the power transformer... Basically turning it into three synched single phase transformers.

    But the Block 3 winding makes me want to ask someone who has seen this type of stacked winding before I ruin a perfectly good charger. L2 and L3 share the limb on the left...
     
  2. mksj

    mksj Active User H-M Supporter-Premium

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    Not an electrician. Just looking at this from a high level, it would appear that L1 and L2 provide power to the control system as you noted. The transformer seems to be setup so each phase of the 3 phase power provides power to the transformer, the output is two separate wingdings with 1/2 wave diodes that are run in parallel, that is the reason for the second set of diodes (2A-2D). It would appear that each phase of the 3 phase input is run in a sequential pattern with two output winding that are also paralleled. Really can't say what the phasing would be and and there also seems some form of sense/feedback circuit on the output between L1 and L2 and between L2 and L3. So it really is up in the air as to the wiring and the phasing of the transformer, as rewiring may result in bucking as opposed to boosting. Also the rectified half-wave output would not be as smooth, since in 3 phase the output peaks are staggered overlap (see below). Given the size and current of the unit, I am not sure I would proceed unless you have some concrete guidance from the manufacture or someone in the know. It may be possible to power L1 and L2 and see what happens, or as you mentioned run each phase in parallel off of L1 and L2 so L1 connects to 1.1, 2.1 and 3.1; and L2 connects to 1.6, 2.6 and 3.6. Remove the jumper between 1.6 and 2.6, also 2.6 and 3.1. Once again not sure on the phasing of the transformer, so everything could go up in toast and be quite dangerous.

    3 phase rectified wave.jpg
     
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  3. Mikebr5

    Mikebr5 United States Active Member Active Member

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    Thank you mksj.
    The 3rd winding doesn't look like it is for Charge Current though. It shares a section of the core with the larger heavier 2nd winding. I'm going to compare the only other drawings that I have found from the same manufacturer for comparison. Mine seems to be a chimera.

    Huh... That is something that I didn't think about. I assumed that the 3rd leg was not a contributor to the heavy current... Your reply is making me rethink that.
    I can't get a USB camera to work on my cell phone or I'd be in deep tracing out the transformer. Gah!

    I see what you are saying... Can you look at the diagram again and see whether you still think that all three phases contribute to the charge current?

    Mine :
    [​IMG]
    Same Mfg, different 3 phase:
    [​IMG]
    Same Mfg, single phase:
    [​IMG]


    Come on man. You know I am going to plug this thing in. A reminder to have the cam running for later enjoyment seems more appropriate to our hobby. :p
     
  4. markba633csi

    markba633csi United States Active Member Active Member

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    Not an electrician but I wouldn't worry about smoking anything, worst would be a blown fuse.
    It looks like for 240v you connect like your orange markup and ignore the 3rd set of primary windings
    Then use L1 and L2 for input power, it may just work. If not some jumpering will be necessary.
    It looks like yours is a quasi-star connection; the other 3 phase model below it is a delta.
    Mark S.
    ps beware of people who say "not an electrician but..." LOL
     
    Last edited: Aug 9, 2017
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  5. markba633csi

    markba633csi United States Active Member Active Member

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    The jumpering (if necessary) would be to break JB1 and connect to SJMP, then add a jump from 1.1 to 2.1
    Mark S. ps also remember to remove the jumps 1.3 to 1.4 and 2.3 to 2.4 and 3.3 to 3.4
    240chgmkup.jpeg
     
    Last edited: Aug 9, 2017
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  6. mksj

    mksj Active User H-M Supporter-Premium

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    Each winding phase is used to generate an output (phase), the schematics are not actual depictions of the physical transformer winding. The second schematic has 3 independent transformers, each one represents a phase, so all three are used and the output is overlapping half-wave DC or what is often called unfiltered DC. You have a single transformer, so the first schematic seems correct. You are faced with the same issue that are seen with VFDs, 3 phase inputs provide much lower ripple and much less stress on the components/capacitors, vs. single phase inputs. Since there is a single phase version, I guess that a single phase 1/2 wave DC would work. I believe the TC on the output is for a current fault feedback system for each output phase (so two for the first, three for the second schematic). If you must try something based on the first schematic (single transformer), I would jumper the control transformer and each phase of the output transformers for 240VAC. Run the charger by just connecting L1 and L2, this would be no different then what would occur if you had the 3rd phase drop out. Measure the output voltage. If you need more current, then you should be able to parallel each input phase of the transformer as previously outlined L1 to A1, B1 and C1; L2 to A6, B6 and C6 with each phase wired for 240 and no other connections between the transformer phases. i.e like the three single phase circuit each in parallel with each other.
     
    Last edited: Aug 9, 2017
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  7. Doodle

    Doodle United States Iron Registered Member

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    If those orange jumpers you have drawn in are actual jumper wires, when DSW and AK are engaged, you have a direct short from L1 to L2 and L3. I hope the fuse can break the current without there being an explosion.
     
  8. markba633csi

    markba633csi United States Active Member Active Member

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    There won't be a short if jumps 1.3 to 1.4 and 2.3 to 2.4 are removed as I remarked in the post above
    Mark
    plus the jump on the 24 volt transformer, I think Mike knows that
     
    Last edited: Aug 10, 2017
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  9. Doodle

    Doodle United States Iron Registered Member

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    Isn't the CONTROL section required for operation? With the transformer marked in the schematic CT, the jumpers short out the primary.

    upload_2017-8-10_6-45-23.png
     
  10. Mikebr5

    Mikebr5 United States Active Member Active Member

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    No, the orange may be ignored . That is just the switching of the control transformer to 240VAC. The orange in the power transformer is switching it from 480VAC to 240VAC. All I did in that drawing was the same thing that would have been done at the factory if it had been shipped ready to plug in to 240VAC 3 phase. I thought that by adding the orange we could skip the 480 to 240 discussion. hah
    The switch from 480 means the jumper between 2-3 on the control transformer is removed. Same thing on the power transformer- orange jumpers go in, the jumpers between 3-4 come out.
    The 3rd leg winding is physically smaller, much smaller, than windings 1 & 2, so while I realize that a schematic is not a perfect representation of a circuit, this is drawn to give a reasonable idea of the layout. Lines 1 & 2 are rectified for charging current, and line 3 seems to be used only as an output voltage adjustment, set by the factory but field adjustable in case of abnormally high/low voltages at the plug.
    A single phase rectifier of the type shown would give a choppy ON-OFF DC voltage... Half wave rectifier. Two lines of a 3 phase input would smooth that out considerably, basically giving a full wave rectifier minus the little bit at the top end where the 3rd leg is missing... It would only be seen on an oscilloscope as a slight 60 HZ depression at the top of the DC trace.
    Power coils are 1 and 2... Coil 3 on the power transformer shares the limb with coil 2.
    So while I still have not figured out how the #2 power coil will affect coil 3 - I will find out by a theory to practice today or tomorrow.
    I would rather have understood coil #3 a little better before closing the switch on it.
     
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  11. Mikebr5

    Mikebr5 United States Active Member Active Member

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    Thank you Mark. I know that you see what I did in an electrical way. I will give a short description of the 480 to 240 to single phase switch.
    The factory sent the charger out ready for 480VAC 3Phase, as can be seen in this:
    [​IMG]
    The Control Transformer is not marked the same as the schematic... There are 4 stabs, marked C (common) 208, 240 and 480. I took the one on 480 and moved it to 240.
    Next I removed one end of the jumper (on each of the 1-3 coils on the power transformer) from stab 4 and moved it to stab 6. I then made 3 additional jumpers and added them from stab 1 to stab 4.
    The switch to 240VAC is complete, but the charger is still set up for 3 phase.
    To switch to single phase I removed L3 from the fuse block, snipped it, wire-nutted it and taped it back to the other three wires. I did it as close to the entry into the box as possible to avoid any energized but unused components.
    Then I removed the wire between L3's fuse and the contactor AK. If it were to be plugged in at this point it would be just like losing L3 during normal operations - I didn't test it at this stage to see what the effects would be. I may do that so someone else in the similar stage can have an idea.
    The next stage was to remove the jumpers between the stab blocks for each of the three coils on the power transformer.
    Mark pointed them out... SJMP and the jumper between 2.6 and 3.1... Now the power transformer coils are separated from their previous Wye configuration and ready to be made "stand alone" single phase.
    Coil #1 - Wire from T2 on AK is routed to 1.6. Coil #1 will have 240VAC across it when AK closes.
    Coil #2 - JB1 is removed from T2 on AK attached to T1 on AK. Wire from T2 on AK is routed to 2.6. Coil #2 is now paralleled with Coil #1 and will have 240VAC across it when AK closes.
    Coil #3- Wire is routed from T1 on AK to 3.1. PC6 is removed from T3 on AK and stacked on the other two wires on T2. Coil #3 is now paralleled with coils #1 and #2.

    I did not do any current readings before this swap, so I do not know what the load of Coil #3 is, but I expect it to be at the signal or control level... hardly anything. I will find out if I am wrong in a bit. Maybe get a shave and a haircut at the same time. heh
    So with a low current draw from Coil #3, there should be no added load (maybe minuscule) to the contactor points by stacking three coils on T1 and T2 and orphaning T3.
    Ready for the fire and smoke test.
     
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  12. markba633csi

    markba633csi United States Active Member Active Member

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    The only possible problem Mike is if the two paralleled coils are out of phase then one or both main fuses will blow. If you want to avoid this (and I would myself) you could do a phasing test before you apply power. What you could do is open one end of coil #2 and insert two series incandescent bulbs into the circuit (do they still make those?), then apply 115v temporarily to L1/L2 instead of 230v. If the lights light up it's backwards. If the coils are phased correctly they should light dimly or not at all.
    Do you follow that?
    Mark
    ps you could also do the same test with an ac voltmeter instead of the light bulbs, just be careful whichever way you do it.
     
    Last edited: Aug 10, 2017
  13. markba633csi

    markba633csi United States Active Member Active Member

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    I don't see why you couldn't utilize the 3rd coil also and get the full power out of the transformer that it's capable of...but try it with 2 first.
    Normally when manufacturers draw transformer (or motor) windings the upper ends are the "start" ends (sometimes marked with a dot)
    and the lower ends are the "finish" so it's easy to figure out the phasing. But they don't always.
    M
    ps BTW the output is full wave rectified. It's called "full wave center-tap"
     
    Last edited: Aug 10, 2017
  14. Mikebr5

    Mikebr5 United States Active Member Active Member

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    I have been synching big 3 phase generators since I was in the service - but I do not see a phasing issue with Coils #1 and #2. I look forward to your thoughts on it. I will address Coil #3 after your next quote.
    Coil #1 and Coil #2 are jumpered correctly for 240VAC. Each is capable of transforming 240 VAC to the appropriate lower voltage AC so that when combined with the other coil's output after the rectifier gives a nominal 24VDC (little higher, though.) So let's keep it simple and say that Coils #1 and #2 transform whatever voltage they are jumpered for down to 12VAC nominal. Since these are two legs used only (not 3!) the charger is using the top of the rectified AC for the positive and the bottom of the sine waves for the DC. That's not exactly the way that single phase transformer/chargers work, as they use a bridge rectifier so that both sides of the sine wave end up on the top of the normal graph.
    I am completely open to being corrected.

    Coil #3 is tiny... and it seems to match with the coil layout in the schematic. Is seems to ONLY be used for the factory/field voltage setting, not for power to the rectifiers.

    It is interesting seeing the different ways that this same manufacturer rectified the AC between the three schematics that I posted... The two that I do not have are very simple- but mine is the chimera that is 3 phase with two power coils and a 3rd signal or control coil, with a 4th stand-alone control transformer.

    We come back to the mystery (for me) of how Coil #2 being used for power (charging current) will affect Coil #3, being used as a control or voltage setting. It did the same thing when 3 phase- I've never seen a 3 phase transformer with only 2 limbs. Before this one I mean.
     
  15. markba633csi

    markba633csi United States Active Member Active Member

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    To me it looks like, in the factory configuration, if you put single phase power on L1 and L2 the upper ends of the winding get juice and they are in series so with
    conventional thinking they are out of phase and no power will be delivered to the output. Null winding. (bucking)
    That's what it looks like will happen unless you do some jumpering. That's why I marked up your markup.
    You would want the two coils in parallel for 230v and according to the schem they are not.
    I figured you had some experience from just your first post. Kinda hard to hide it :cupcake:
    Mark
    ps the full wave center-tap gives the same result as a bridge rectifier, it's just a little cheaper to manufacture, the trade-off is having twice the turns and a center tap secondary to save 2 rectifier diodes and their heatsinks
    pss I don't fully understand the deal with the 3rd coil either if it really is much smaller like you say.
    must be some goofy 3 phase thing- from another planet obviously. Alien technology.
    if you measure the same voltage across it as the other two then you could connect it as a power winding as long as it's in phase with the other two
     
    Last edited: Aug 10, 2017
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  16. Mikebr5

    Mikebr5 United States Active Member Active Member

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    *Lightbulb pops on above head* *Slaps forehead*
    Yes! Thank you very much for being patient with my demonstrated ignorance/stubbornness.
    I now see what you are saying.
    I will look over your mark up again.

    This makes me question my insistence that Coil #3 isn't a power coil just like #1 and #2.
    mksj kept saying it and I kept saying "but this, but that"... Sorry if I wasn't hearing you clear mksj.
    [​IMG]
    It is the same voltage jumper circuit between the two rectifier sets. I saw it but was not grokking it.

    Now there are a whole new set of schematics to look at and I am going to try to peer inside the transformer set up now that you and mksj shone a flashlight into my cobwebby brain.
     
  17. Mikebr5

    Mikebr5 United States Active Member Active Member

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    Now that I let go of my "Coil #3 no contribute!" stubbornness I am able to read what Mr mksj meant here.
    You know how it can be tough to let go of something... hah
    I am still fighting to keep my belief that 1.7 through 1.12 are a factory set field adjustable voltage adjustment for high or low line voltages.
    Can you describe how that TC circuit would function as a current fault feedback system? My electronics background is at the hobby level. I see the R-C portion and see part of an oscillator circuit.
     
  18. markba633csi

    markba633csi United States Active Member Active Member

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    Oh I see- I was ignoring that stuff altogether- Think "Sola" CVT constant voltage transformer;
    crude Frankenstein technology. They should have just changed the output rectifiers to SCRs and used a phase control feedback scheme... oh well. Never mind. LOL
    M
    I think mk pretty much has it figgered out- better than I
     
    Last edited: Aug 10, 2017
  19. Mikebr5

    Mikebr5 United States Active Member Active Member

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    I wasn't keying on that circuit- Just saying that when the lightbulb went on about what you were patient enough to explain a few times, I was able to go back to mksj's replies above with fresh eyes.
    Ferro-resonant ... I kind of blew by that in my education (or just forgot after a few decades) and went to Google for what I thought would be a simple refresher.
    It turns out that that 3rd coil may be the key to how the transformer gets the phasing right. The 3rd coil "unbalances" the transformer to cause the phase shift. I think! *mindblown*
    That'll teach me to think I know enough. A "simple" battery charger circuit req'd an epiphany, and thanks to you and mksj's kicks in that direction.
     
  20. markba633csi

    markba633csi United States Active Member Active Member

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    I'm trying to learn Arduino programming and it's hard at my age (62) my memory is not near as good; the young kids run circles around me.
    I know how you feel. Anyhow, let us know if you get it working
    Mark
     
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  21. Mikebr5

    Mikebr5 United States Active Member Active Member

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    This is one of those cases where a fellow walks in thinking he knew enough, only to find out that he'd missed most of the prep classes.
    I feel like this stubborn cat with you and mk taking turns on the leash.
    [​IMG]
    Now that I have an inkling of how ignorant I am I will try to start fresh.


    You've got a few years on me sir, and I am an Arduino fan myself. *cheers*
     
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  22. markba633csi

    markba633csi United States Active Member Active Member

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    Have you done many Arduino projects?
    Mark S.
    ps that looks like my cat lol
     
    Last edited: Aug 12, 2017 at 12:37 AM
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  23. Mikebr5

    Mikebr5 United States Active Member Active Member

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    I have done a few dozen of the prototype projects on breadboards. There are also a couple of remote sensor projects that received their own project boxes and are mounted in permanent enclosures. After I get finished moving from one state to another and finish building a house, then I plan to sit down and try to learn the programming more so I don't need to be hunting and pecking through the books and canned sketches.
    The rotary phase converter rebuild was going to be an Arduino-controlled piece of marvelous engineering (hah) with nicely written ladder logic, pretty colored LEDs as the Arduino stepped through the checks, start, caps in and out...
    I have to chuckle at how plans are scrapped so easily when the schedule goes out the window.
    This 3 phase to single phase charger was not the only project that turned out longer and more complicated than I thought it was going to be this week.
    I also tore into a Clark NST25 electric forklift that I thought I could have running inside my shop by the end of this week.
    :laughing: Now I have a 5300 pound walk-around piece of art in the center of my work space and a 1300 pound top heavy battery on a pallet outside the shop. And my wife informs me that rain is coming tomorrow.
    There are two 24VDC motors driving 2 separate hydraulic pumps in the Clark... The one that operates the drive wheel looks to have burnt windings near the brushes.
     
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  24. markba633csi

    markba633csi United States Active Member Active Member

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    Ah now I see what the charger is for. Looks like you'll have to tarp the battery.
    I'm hunting and pecking my way on an Arduino stepper controller now using borrowed code but isn't reliable; I'll probably end up rewriting it.
    Like the old saying, if you want something done right do it yourself
    Mark
     

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