Transformers in phase?

This video explains it pretty well

I’m not sure what you mean by MTH Railking controller.  MTH control device product numbers start with 50.  Railking product numbers start with 30.

Power coming out of the #2 and #4 transformers should be in phase.

That Lionel video is probably very thorough.  I didn’t watch more than a few seconds.  All I do to check for phase is connect the common terminals together, attach wires to the positive terminals and set the voltage on the transformers to the same setting (about 10 is good, but if yours are fixed at 20 I guess that’s OK).  I then brush the free ends of the positive wires together.  If there is no spark, they are in phase, I there is a spark, they are not in phase.

Current UK plugs look like they are polarized so if you find yours to be out of phase, you need to switch wires between either #1 and #2 or #3 and #4.  Then retest to make sure you are good.

All the transformers must be in phase.

The "MTH Railing Controller" takes power from those transformers, so it is not involved in any of the phasing operation.

MTH Rail King Controller

I’ve always found electricity incomprehensible, I got about 30 seconds into that Lionel video....

so, if I understand this correctly, the transformers will be in phase, or 180 deg apart; there are no other possibilities. I can determine this by wiring up the two lines (because the thumbscrew terminals on the controller outputs, are the easiest place to change wires) setting the controllers to 60% or so, connecting the BLACK terminals on the two controllers, and brush the ends of the RED wires together.

If no spark, no action is required.

If there is a spark, switch the BLACK wire to the RED terminal on ONE controller. Switch the RED wire on that controller to the BLACK terminal and repeat the test. There should be NO SPARK and both BLACK wires can now be wired to the Common Return. The RED wires can be wired to the HOT (centre rail) side of their respective tracks.

Is that it?

"We" just had this discussion over on the S-Scale forum (one of the fora under Home/train forums) - if you scroll down you'll see a set of posts under "Phase two American Flyer 12B transformers" (I should know how to make a link to another OGR post, but I don't...).  Included in the discussion are two links, one in my post to "Marty's" and in the subsequent post from Amflyer, to traindr.com.  both are good and are much, much better and more straightforward than the Lionel video link up-post from here (which is a bit of a mess, IMHO).  The main problem - at least on this side of the pond - is that many of the older transformers have two-prong plugs and are not polarized, so its possible to plug one transformer in with the plug oriented one way and the other transformer in just the opposite way.  The spark method will work, but its a lot more qualitative than using either a volt/ohm meter (the best way) or using a light bulb.  Just remember to label the plug orientations.

I don't know whether the UK 220VAC is single phase or three-phase.   If the latter, I suppose that could complicate this.

I’ve always found electricity incomprehensible, I got about 30 seconds into that Lionel video....

so, if I understand this correctly, the transformers will be in phase, or 180 deg apart; there are no other possibilities. I can determine this by wiring up the two lines (because the thumbscrew terminals on the controller outputs, are the easiest place to change wires) setting the controllers to 60% or so, connecting the BLACK terminals on the two controllers, and brush the ends of the RED wires together.

If no spark, no action is required.

That should work, but as Rich said, it’s better to have all in phase.  If your transformers are all modern and of the same make, they probably are.  Be good to know what the 220/110 and 110/20 transformers are, what the plug the that goes into the wall socket looks like and what the interconnecting wires look like.

The controller set appears to be MTH 40-750C with a Z-750 controller.  Those are rated at 75 watts so if your transformers are rated for at least 150 watts, you could run both Z-750s from one 220/110 and 110/20 transformer pair and not worry about phasing them.

U.K. domestic current is 230v single phase.

One transformer I currently use is a Helmsman 230v unit with 12v DC and 16V AC outputs (originally supplied for O Gauge 2R). Regard this as transformers #1 and #2 combined. This has thumbscrews coupling the wires to the controller.

The other is a new 200W 230v / 110v unit (transformer #3) which will feed a 100W 110v / 20v transformer (#4), with an integral output lead fitted with a coax plug for the controller.

This means that the only accessible connection, where the wires can be swapped is on the controller output.

Any sort of 110v or 20v AC equipment is hard to find in the U.K. so the “output wires” check sounds like the best approach.

Couldn't find anything on the Helmsman transformer.  I came up with Helms-Man transformers which are wall warts.

If your Helmsman has thumbscrews for the wires to the controller, that seems like the best place to switch wires if need be.

@Lehigh74 posted:

Couldn't find anything on the Helmsman transformer.  I came up with Helms-Man transformers which are wall warts.

If your Helmsman has thumbscrews for the wires to the controller, that seems like the best place to switch wires if need be.

Currently out of production, supposedly returning under new ownership,.. https://www.finescalebrass.co.uk/dc-controllers.htm

I find that the transformer delivered with the new RailKing controller has two sets of output terminals, total 180W. So I can rig one controller to each, and solve the problem at source.

The carpet test track isn’t big enough for voltage drop to be an issue.

I like going over this easy stuff, I haven't phased transformers in years.