Post war ZW transformer circuit breaker pops after 5 - 10 minutes of running 3 trains simultaneously; what's up?

Only you can tell. Take a meter and measure the total current in Amps. Multiply by the voltage (use 15 Volts as an example)  The answer is the power being consumed in Watts.  A ZW will supply around 200 Watts on a good day in a cool room.  This is the simple method to get a rough idea of the power being consumed.  

If you don't have an ammeter that will measure up to and beyond 10 Amps, measure each train by itself and add them up.

If you divide 200 by 20 (Watts by Volts) you get 10 Amps. I don't know what the rating of the circuit breaker is, so you need to look it up or ask someone who might know.  If your total power exceeds 200 Watts, I would imagine that the cb is doing its job. I would not suggest using a cb that is rated for higher current.

I would get a second transformer.

Dave,

Perform the math Arthur has prescribed above. If you are over 10A or so, you need more power (Why not another ZW - just put it in phase with your current one). If you are under 10A, your circuit breaker may be worn out. They are easy to replace. Depending upon your ZW, you can use one of the three:

Z22: 

ZW-232:

Modern Automotive Bussmann 19115 assembly: 

I would suspect poor track conductivity:  either between sectional track connections or electrical connections to the track, or both.  Or poor maintenance of locomotives; i.e. dirty wheels, track, rollers. etc.

Something other than the engines and passenger car lighting is sucking up amperage.

Drummer3 posted:

Are my trains drawing too much current for a 275 watt ZW?  Here's what I am running :

1.  MTH PS1 Hudson with 4 MTH lighted passenger cars.

2.  Lionel Silver Spike passenger set - both diesels lighted as well as 3 lighted passenger cars.

3.  AF passenger train (1992), both diesels lighted and 4 lighted passenger cars.

The circuit breaker automatically resets after about 2 minutes, I guess when it cools down.

Do I need to put in a higher amp circuit breaker perhaps?

Any suggestions appreciated. 

First question: yes

Second question: only if you want to fry your electronics/start a fire on your layout....

During the 1990s I was still using 3 pw ZWs [each on separate tracks] all of which at one time or another when loaded at 8-9 amps on my high shelf railroad, tripped out after about 20 minutes of continuous running. Based on my AC Ammeters,wired indivually on each power district[track], when converted to watts, it indicated 180-190 watts  was about maximum load for my well maintained ZWs when running continuously. Typically I ran two trains on the same track, usually one was a long lighted unit of 10-11 cars.

Eventually changed over to 180 watt PoHos , TMCC and changed to LEDs in lighted passenger cars--no further problem with tripping.  Just as info,180 PoHos [bricks]have the fastest reacting circuit breaker of any transformer I have ever used.

"I would suspect poor track conductivity:  either between sectional track connections or electrical connections to the track, or both."

Could you explain how adding resistance to a circuit would increase current draw?

Eleven lighted passenger cars and four engines?  They may not be over the 200 watts, but I'll bet they're getting close.

Another possibility is the old circuit breaker is failing or at least mis-adjusted.  The way to really test this is to do a load test on the bench.  What used to be a good load is old automotive headlight bulbs, they are in the 50-60 watt range.  That transformer should be able to light three of them indefinitely at 12-14 volts output.

This evening I measured the amperage on the 3 loops I am using.   They all read 1.7 - 1.9 amps, or just under 6 total when all 3 trains are running.  So, perhaps the 10 amp breaker  is faulty.   What does 6 amps convert to in watts on this transformer?  Also, is it truly 275 watt output as stamped on the transformer?

 Another idea is to do away with the internal breaker and install external breakers, that is,  give each output post (A B C and D) its own external breaker, perhaps a 5 amp on each??

Well, the 275 watts in input power, that's how PW transformers were rated.  For continuous output power, figure on around 75% of that, and that's at full throttle.

If you're only drawing six amps and the breaker is tripping, time to replace the breaker.  Many folks use an automotive cartridge type breaker as a replacement, if you use a socket, you can even tinker with the rating of the breaker easily.

Dave, based on your readings, your internal breaker is worn out. You definitely should replace it with one of the ones I previously mentioned and not simply bypass it. You are free to add additional breakers to each individual output, and many would correctly state that would be best practice to do so (to protect against cross output currents), along with TVS diodes (such as 1.5KE36CA). Additionally, the 275 Watt rating is house current power consumption. Best to assume about 75% efficiency, hence the 200W output Arthur mentioned.

The Lionel test specs for the ZW transformer is that it should put out 30 amps for 11 to 40 seconds before the breaker trips.  It sounds like you are no where near this.  So the breaker is probably worn out.  There are lots of replacement options. 

Sounds like I will try the 10-amp automotive type breaker, and add an external TVS on each post.  Thanks for all the tips!

Dave, for what it is worth, the ZW breaker is actually 15 amps.

 Another idea is to do away with the internal breaker and install external breakers, that is,  give each output post (A B C and D) its own external breaker, perhaps a 5 amp on each??.

For safety's sake, the internal circuit breaker should remain, and be working properly. Down the road, that transformer will fall into someone else's hands, who will not know that the breaker has been removed. It could even be a family member. That written:

David Johnson wrote:

The Lionel test specs for the ZW transformer is that it should put out 30 amps for 11 to 40 seconds before the breaker trips.  It sounds like you are no where near this.  So the breaker is probably worn out.  There are lots of replacement options. 

That is a lot of power for a long time.
The internal ZW circuit breaker is there to protect the transformer, not your trains or layout wiring. Plus, it is fairly easy to accidentally create a circuit that is not protected by the internal breaker. I always put an individual breaker on each "Hot" output, terminals "A" through "D". I like to use Lionel postwar #91 adjustable electromagnetic, manual reset circuit breakers. There are many choices.
If any of your trains have circuit boards, a TVS on each output is a good idea too.

I'd say, the ZW's are doing what they are supposed to do - protecting.

The "trippers" are the passenger consists. Too many light bulbs, I concluded, during a personal experience running my layout.

In my limited personal experience in this regard, I have used these 5 ZW's (10 trains altogether; 2 per ZW, using only the two large handles on each for trains,) since inception of the layout in 1995. The only time the ZW's have given me any grief was when I tried to run (TMCC) TWO (8-10car) passenger trains on the same track. The ZW responsible for the initial trip-out went out after, approx. 3 minutes.

Then, I changed both trains over to a different ZW; same result - tripped-out.

It wasn't the two steam engines on the same track and ZW arm that were pulling those passenger consists that seemed to be the critical factor, because as soon as I changed one train over to freight, no problem with tripping.

My conclusion? Though the lighted windows seem innocent enough, they apparently add up to quite a drain. Thus, they trained me  and I modified my behavior to not run two passenger trains on the same ZW handle.

FrankM, Moon Township

P.S. For more particulars, I refer you to my betters, above, like CW Burfle. Those guys know lots of stuff. I just want the trains to move and look good doing it,; beyond that, my usual reaction is "Huh?'", and I call over to the house a specialist (he's the guy who designed and installed that ZW cache, as well as wired the entire layout, with connections every 4-6 ft. along all the ten independent loops.

bmoran4 posted:

Dave, for what it is worth, the ZW breaker is actually 15 amps.

Yes, but considering that's more than the ZW can actually usefully deliver, 10 or maybe 12 is a more realistic value.  The old PW breakers were just there to keep the transformer from frying, and they didn't even do that all the time.   A 10A thermal circuit breaker will tolerate a 20% overload for quite a long time, so a 15A breaker is way more than necessary for the ZW, at least IMO.

 Moonson posted:

My conclusion? Though the lighted windows seem innocent enough, they apparently add up to quite a drain. Thus, they trained me  and I modified my behavior to not run two passenger trains on the same ZW handle.

You need LED lighting, then the passenger cars will be light freight cars, no power issues.

I understand that LED lighting needs very little power,  but still, my 3 fully lighted passenger trains only draw 1.7 amps each.   Does anyone know how many watts that is?

  I am guessing about 40 watts per train ??

So, 3 trains x 40 watts each = 120 watts, which is way under 200 watts that the ZW can supply.

W=V*A

14V at 2Amps is about 30 Watts, or ~90 Watts total.

18V at 2Amps is 36 Watts, close to your 40 estimate.

Your internal circuit breaker seems to be worn out and needs to be replaced with one of the ones I mentioned way above at the beginning of this thread. As stated earlier, TVS diodes are a good addition, along with smaller breakers for each throttle.