phasing vs higher watts

 I have O gauge tin plate track that I have reconditioned, Is it better to block your track with several transformers of just use one with high watts like the Lionel ZW or MTH z4000

President and Chief Executive Officer

Suecity Railroad 

Original Post

Well, the PW-ZW only cranks out about 200 watts or so in real output, and the MTH Z4000 is limited to 10A per output, so you don't get really "high watts" with either of them.  You also cannot parallel the Z4000 outputs to get more power.  As far as power districts, it really depends on how you run and how large the layout is.  Also, command of conventional will enter into the equation.


There is no one size fits all answer.

Amount of power has nothing to do with how much rack you have or how long the sections of track are.  It has to do with how much power will the stuff on the track consume.  If you use proper wiring techniques with higher current feed wires that distribute the power to the tracks via multiple lock ons or direct track feeds you don't need any more power than you would for a small oval.  Track is a lousy conductor of electricity and you should not try to use a single lock on/feed for a loop unless it's really, really small.  I use two feeds for the Christmas layout and it's only a six by ten foot oval.

Quando Omni Flunkus Moritatum

I'm not clear on where yoru question is going or why.


Yes, you can block your track into sections nd use small transformers to serve each section but the power they provide will not add to a number larger than the rating of any one of them.  For example, if you have four sections each powered by a single transformer than can provide 40 watts, you have a total of 160 watts of transformer, but can run a train requiring 40 watts but no more.  (Technically, there is a possible exception but it is not practical.  If you have lighted passenger cars in a train that is longer than any section fed by one of the four 40 watt transformers, then the cars will split their demand for power, some pulling from one section's transformer, others from another's.  So you might be able to run, say, an old Pullmor loco that demands 30 watts and a bunch of lighted cars that need, say, 30 watts alos, for a total of 60, and get away with it.  I would not count on that, however.) 


If you want to run a power hungry train, or several trains at once, its best just to get a honking big transformer or brick and feed the entire loop with it.  Install a single transformer serving all four blocks, rated at 160 watts, and you can run a 160 watt train, or two 80 watts trains, etc.

My layout is a total of 96 feet on the outside track with one turnout. I have 3 seperate tracks one inside the other to run 3 different trains. Each line of track is seperate from the other and each line has a seperate transformer. Should I keep them seperate or coneect them all together and run one big transformer 

President and Chief Executive Officer

Suecity Railroad 

Actually this is an interesting read, so if I may ask,:
If your trains are drawing additional amps with many added passenger cars, and you already have added many feeds, how do I determine if more feeds are required, a bigger transformer, phase more transformers,  or am I trying to run too many trains?
Right now my ZW gets very hot to the touch, but after 4 hours plus of running, 3 long passenger trains with some accessories.

TCA Number 16-71884

When your pw ZW get hot it loses efficiency but as long as it doesn't trip a good, reliable breaker you are okay. That is why most everyone recommends a reliable external breaker or fuses to replace the old internal original equipment breaker on the pw ZW.

A cooling fan on the newer Z-4k reduces the heat problem applicable to the pw ZW. I have read of O-gaugers ventilating the pw ZWs case and blowing air over it with a small fan but have never seen one so modified and equipped.


A regards frequency of track connections you can measure for voltage drop under load[both with all train consists running and clear of trains]with a portable meter by comparing the reading at the transformer post to that of the distant location. Also, check to see if your long trains are slowing at the far distant point. I have always used permanently mounted analog AC amp and volt panel meters[fuzzy photos] to monitor at a glance the voltage and amperage load for each of the power districts.The panel meters can be an indicator of some problems but you still have to trouble shoot and find it. A portable meter is very useful for trouble shooting. 


As indicated in an earlier post, I have operated "super powered" districts by paralleling fixed voltage Power House transformers, both 135 watt and 180 watt. But today I have no need for more that 180 amps per district.

If you use a test track to short and test the effect of a derailment on, for example, a pair of paralleled 180 watt transformers[20 amps] you will quickly learn that you have achieved scale welding capability. I used a pair of 135 watt effectively and safely, equipped with a magnetic circuit breaker.  I can see where some Clubs with very long trackage might desire that kind of power or even 20 amps for very long, multiple trains as opposed to utilizing blocks. 

Analog Meters-002



A&Y RY[NC's Southern/N&W connector].


Photos (2)
Wow very nice! So in order to root cause what is going on...
I have measured those areas of the layout with a DMM in volts, and I am reading a voltage drop that varies from 18 to 17 at the terminals, at the track some locations are 17 others drop to 15. As more trains are brought onto the main the voltage drops to 13.  There is a 3 percent grade where trains begin to stall as operating times exceed 4 to 5 hours. My layout is about 1060 square ft.

TCA Number 16-71884

The ammeter will read the same regardless of where it is in the circuit.  The different voltage drops are simply a product of resistance along the current path, but the current in the path is constant at ever point.

I agree with John on both the use of LEDs in passenger cars and the ammeter readings. LEDs in passenger cars are more efficient and cheaper than buying new transformer capacity. IMHO nothing wrong with using repaired and well maintained pw ZWs.

The two photos shown in my posts up above are from layouts in two different homes, here and the mountains, dismantled in 3/08 and 10/09.

Operating a much smaller and simpler attic layout now, more in keeping with my old age, lame legs and lame brain. Current power center for two districts shown below.

Attic Layout 076

A&Y RY[NC's Southern/N&W connector].


Photos (1)

J Daddy;

Fastest help is going to be Run less train at any one time or use a Much Bigger Transformer

Then running a new heavy wire power drop to the middle of any area with low volts.


And I agree with gunrunnerjohn, Converting lighting to LEDs will reduce your power needs dramatically so you don't need a bigger transformer.


The Drop to 13 volts shows you are overloading the transformer, or nearly doing so.

You will always have loss in the track, but it should not be more than a couple volts at any point.

If you want to run several trains with lots of standard lighted cars, you will need the Biggest Transformer you can get or one medium to big Transformer for each loop or block.

Understood, unfortunately LEDS are not an option when hosting a round Robin get together.
I agree about the amps should remain the same unless there is transformer drop in supply in wattage. Which is what I think I am seeing too. Is this where phasing power. Helps?

TCA Number 16-71884


Isn't the resistance causing the IR drop coming from the track itself which can be overcome by connecting additional properly sized wire runs at strategic places where the voltage is low?

If the train consist[s] were overloading the transformer it should trip unless it has a faulty breaker. Ten amps or 180 watts is the maximum any O-gauge transformer produces per throttle or in total by a pw ZW which he uses, unless you parallel Power House bricks through a TPC.

A&Y RY[NC's Southern/N&W connector].

Dewey, You are of course, correct. I was addressing the voltage drop from my suspected cause.

Transformers have a unlabeled and unspoken capacity called "Stiffness". That is, they tend to droop the voltage as they approach the rated output. MTH bricks have good stiffness in that they do not droop much. I can't speak specifics on others but it is a known factor. The cheaper the transformer (the actual transformer inside the controller) the worse the droop is.

That drop to 13 volts is probably a combo of all these issues. Droop, needs another power connection, and needs heavier wire from transformer to near the track.


Making lots of short blocks and alternating them between phased transformers will spread the load of a long passenger consist and engine onto 2 or more blocks. If you have 3 Transformers, you can spread it across the three transformers by using fairly short blocks. Just tie each transformer to the next block in order, 1, 2, 3, 1, 2, 3... Then each transformer carries part of the total load. This does make for a wiring nightmare, Label or better yet, color code the wires. You will still eventually overload if you run multiple trains as the trains will be hitting blocks loaded by other trains.


And good circuit breakers or Fuses on each Transformer output and a bipolar TVS across each transformer output is a very good thing.


I will now post this before it becomes a dissertation

Thanks for the reply Russell.

Back in the day I ran conventional with "cab control" and all the insulated blocks that involved, so I get your explanation. During the '50s I was using smaller Lionel transformers before I could afford a pw ZW. I probably experienced the voltage issues you are describing but didn't know enough to recognize it.


Nowadays I favor TMCC but still run conventional occasionally, in particular for the Grandkids engines. I have 180 Power Houses linked to a TPC for each of my two power districts and control both TMCC and Conventional operation from the Cab 1. My pw ZWs have been refurbished, one for the Grandkids and the rest retired to the test track and "museum". Now only a small 9x16 layout with short trains and low power demand.


Anyway, I am getting obsolete and probably should stay out of current discussions.

A&Y RY[NC's Southern/N&W connector].

While transformers do indeed have a "stiffness" according to the design, if you're seeing a significantly higher voltage at the transformer than the track, it's attributable to voltage drop between the transformer and the track and not transformer characteristics.

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