3 phase charger to single phase

[Mikebr5]

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

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:

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.

 

[markba633csi]

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.

 

[markba633csi]

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"

 

[Mikebr5]

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.

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.

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"

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.

 

[markba633csi]

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
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

 

[Mikebr5]

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)

*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.

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.

 

[Mikebr5]

Now that I let go of my "Coil #3 no contribute!" stubbornness I am able to read what Mr mksj meant here.

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).

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.

 

[markba633csi]

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

 

[Mikebr5]

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.

 

[markba633csi]

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