3 phase charger to single phase

[Mikebr5]

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.

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:
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.
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...

 

[mksj]

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.

 

[Mikebr5]

Thank you mksj.

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 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.

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.

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!

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).

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 :

Same Mfg, different 3 phase:

Same Mfg, single phase:

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.

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.

 

[markba633csi]

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

 

[markba633csi]

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

 

[mksj]

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.

 

[Doodle]

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.

 

[markba633csi]

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

 

[Doodle]

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

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

 

[Mikebr5]

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.