ZW circuit breaker

I don't like this test with no fuse or breaker. With blocked points theory is sound, but to dangerous in general. One slip and welding could start easier. Not a chance at shut off till you grab a hot cord to unplug it, bad getting worse is guaranteed. A fuse/breaker cuts those odds.

Meter- See what each train, car, lights draw in amps at X?-volts over 10 min or so, add them up. Less than 10a?

Fuses- 10 amp, maybe even a slow blow if you go glass. Use the common post(s) closest to the internal wire feed. Post-to-fuse-to-track & lights. Run it. Breaker trips? Its bad. Fuse blows? And you have over 10a draw. You might try a 12a, if very curious and brave 15a fast blow fuse. Modern plastic automotive fuses don't have a speed selection but work. 

Adriatic, a slow blow fuse is designed to withstand the heavy starting loads of a large electric motor.  It should not be used on a train layout because it doesn't provide adequate protection for the layout.

I don't like working on an unprotected circuit either.  But, in order to test for an internal short, current flow across the breaker has to be measured, which requires that it be out of the circuit, unless you unsolder one terminal and connect a non-clamp-on AC ammeter from the cb's unsoldered terminal to the wire just unsoldered from it.  This requires working in a small space, with 120-volt power on, and to me it's too dangerous and difficult.

 Jumpers should be securely placed while off, and unplugged in this case. Blocking the points, if exposed, [are they? I thought I saw the points on one?], would take it out of the circuit for any short test, no soldering.

   I would not use a high voltage glass SB permanently. But for a test on a circuit designed to handle 15a I'd rather avoid peak cuts right at 10a and go for constant over 10a for a second or two. Still well below the 15a. peak that should cut that slow blow right in half. And that still got us at around 80% rated max right? I repaired things hands on, not a lot of schooling. Good logic but my "schooled" theory is weak sometimes. I cant go toe to toe on some theories with you guys, I only know what Ive experienced, and taught myself. It fed me for years. I see my lack of going deeper as to me being used to closely watching, and testing with different fuses was a "safety" mistake. But SBs aren't always only for motors. An dedicated/important constant load, using close fuse ratings, but needing some minor unexpected peaking tolerance too, might benefit from a well selected permanent SB.

Your idea of the clamp-on meter on an alligator clip bypass is actually OK.  You won't read the current until the breaker opens, but then you will be able to see what load amount is actually opening the breaker.

Yes Dale that's what I thought, except I didnt know that there would be no current measurable until the breaker opens. Thanks for that. You guys are awesome, but I am pretty much over my head here, altho I get the feeling I've learned more herein the last couple days about this than my local train guy knows. I have that DIY spirit so I probably will do the alligator clips and clamp ammeter and will let you know what I find. 

This Forum is a great place to extend our knowledge while having very strong support from a great bunch of mentors.  You are wise to take advantage of this opportunity!  I learn new things every day, and I try to share my knowledge with others in return!

Dale's approach will work when/if the breaker opens.  Be real careful with alligator clips, as they are prone to pivot and may touch something they shouldn't.  There is no short protection for the clip that's on the winding side of the breaker, if it should touch anything.  If you can get them, insulated clips are preferable.

Thanks to Dale and RJR, and everyone else.  I ordered the clamp meter and some insulated alligator clips as advised. I hope to post some followup on this in a couple of days.

Bob, you'll find it well-nigh impossible to get a clamp meter into the recesses of the ZW, unless you can find one tinier than I've ever seen.  Solution is to disconnect one end of the wire on which you wanted to run the test, making sure the loose end doesn't touch anything, and then use a long jumper to replace it temporarily, long enough to get outside the case.

I was just going to put the clamp on a 1 foot length of the jumper wire bypassing the CB. Wont that work?

The last time I had to see where a circuit breaker was tripping, I used some light bulbs as a load. I have some 12 volt, 60 watt marine lamps for starters, as well as some airplane reading light bulbs.

I used a good meter to see what they were drawing, and loaded up the transformer, putting the bulbs in parallel, until the breaker tripped.

In this particular case, I did replace the breaker.

Yeah that's another good idea. It's one problem after another over here. Now this morning the transformer won't run anything. If all stock is removed I get voltage on the tracks and no red light, but when I put a loco on, they just sit there. And the red light grows stronger as you turn up the voltage. Does that mean a short somewhere on the track?

It means the circuit breaker is open.

The red light is wired in parallel to the breaker. It lights when the breaker is open.

When there are no locos on there I get no red light, but when there is one, the CB doesn't click on, the red light just gets brighter as I turn up the power.

Bob, I'll explain to you what is happening.  Let me first describe how the ZW is wired.  A wire goes from the secondary of the winding to one of the circuit breaker terminals.  Another wire goes from that same terminal over to the red bulb.  From the other terminal of the red bulb, a wire is run, through a resistor on most ZW models, to the U terminals.  From the other terminal of the circuit breaker, a wire runs also to the U terminals.  When the circuit breaker opens, if there is a load on the transformer, current will flow from the secondary winding to the terminal of the circuit breaker to the red bulb, through the red bulb, through the wire and resistor to the U post and out onto the layout.  The load provided by the 6 V bulb (a different bulb on some models) and the resistor prevents an external short circuit from overloading the transformer.  If the breaker should be stuck open but there is no load on the transformer, the red light cannot light because there is no place for the current to flow.  If the circuit breaker is open, and there is no external load (like trains or accessories) on the transformer, a voltmeter will still show voltage on the tracks when a handle is pushed up, because, with no current flow other than the tiny load of the voltmeter, there is no or minimal voltage drop across the red bulb and resistor

Does the condition you have just described exist regardless of which circuit, A, B, C, or D, is activated with a load (not the same load, please), with the other three circuits turned off?  If the answer is yes, then I would say the probability is that your circuit breaker has now failed in the open position.   If the answer is no, then you may have a short in the loco.  Also, with the transformer case open carefully look at all the wires, especially around the circuit breaker, the U terminals, and the red bulb, to make sure that no wire is touching what it should not.  Be especially on the watch for any stranded wire is where a single strand may be touching something it shouldn't be touching.

I was just going to put the clamp on a 1 foot length of the jumper wire bypassing the CB. Wont that work?

 

It should, with cb open.  Be careful with the clips.

A fundamental aspect of your explanation should be mentioned - it is important to realize that a resistor limits current, not voltage.  A reduction in voltage in the circuit however may result. The circuit must be tested under load.

You're back to square one.

Just replace the breaker. It was failing, and is now failed.

Yep that was my conclusion also, and I asked the seller if he'd split that cost with me. Thank you Rob.

Rob, I was trying to explain to Bob why he was getting a voltage reading on the track when there was no train aboard, i.e., no load.

I shan't get into a discussion of what a resistor limits; that is adequately covered in Ohm's Law.

Given Train Tender's price for the breaker, noted above, I wouldn't even bother with the seller, who may not have known of the problem, if he only used light loads.

Hey but you know Rob, it's not back to square one. I have learned a heck of a lot about the ZW these last few days thanks to you guys. I'm going to have my local guy change out the CB later today.

Okay, the 3rd page of the learning curve. But still,the ZW's breaker should be replaced.

How is the power cord? Is it still flexible?

Postwar Lionel train transformers are often in need of a new cord, regardless of the condition of the rest of the transformer.

The cords get brittle and crack, exposing the conductors inside.

If the power cord needs replacement, and you have multiple transformers which are properly phased, care must be taken to get the polarity correct.  In the old transformers I've seen, the terminals for the primary coil were interchangeable.

If the original plug was not polarized, either with 3 prong (2 blades, 1 round) or one blade larger than the other, this is the opportunity to set the transformer so it can't be plugged in wrong.

Happy Pappy, I haven't heard any impatience.  If you look at the total number of views for this thread, it's considerable, meaning that there was considerable interest, which I'm sure included some who wouldn't have asked the question.  Bob asked for advice, and he received it from many persons, who filled in the gaps and caused clarifications, and illustrated that there may be various ways of approaching a problem.  To me, the forum, is a better place to ask questions that LHS.

Well guys I am happy to report that having the local train shop replace the CB this afternoon has given my layout a whole new lease on life. What a difference in the power output too. Trains run way faster at any given position on the handle wheel than they did before. I don't know why replacing the breaker would do that. Strange thing is the train guy still thought the old one he was replacing was operational. There were a few minutes when I wondered if the diagnosis was botched. Not so. Trains run great and I was able to put the lights circuit back on the ZW with no problem. Tomorrow I will put the O22's back to track power and see if that too holds. I really appreciated the help and support from you guys. 

Great!  If the contacts of the CB were bad, they would constitute resistance, lowering power to the layout and heating uo the terminal strip in the breaker.

The power cord is polarized and looks relatively new so I am in good shape there. The train guy had wanted to replace the rectifier, but I didn't feel it was necessary from what I read in this thread.

You are on the right track to test the ZW with a clip on ammeter.

It is always better to run only trains (and track operated accessories) on the train control transformer and get separate 12 or 14 v fixed transformers for accessories.and lights.  These can be had from low voltage lighting systems or other sources.  I use two 12v transformers for lights and one 14 v for non lighted Marx switches, some wired to throw in pairs.

I do not trust the circuit breakers on my three Lionel LWs and have 10 amp, button resetable circuit breakers, with 18 volt light bulbs wired across the circuit breaker, to indicate when the CB has tripped.

I run two trains, powered by Lionel 2035s, one with 3 or 4 lighted 2400 passenger cars and the other with several lighted cars or motor driven cars like the aquarium car with one 125 watt LW with no problems.  The loops are blocked with relays to slow down the faster train to eliminate rear endings.

Charlie

Glad to hear it works as intended, a part gone bad can sure have unexpected consequences on electronics.

Hey, the cord may already be polarized to keep it in phase with some modern stuff.

I don't have a hole lot of modern, but the modern have been in phase with each other out of the box each time. I know there are exceptions to every rule, but if it ain't broke don't fix it. 

Seeing how you do have a few, and might be tempted to mix circuits between them. You need to look & learn transformer phasing. It may be a tad confusing at first, but not hard as a memorized skill. My Grandpa even walked me through it by phone as a kid, but I didn't "learn" much about it for another 15-20 years, but I could do it. I like a bulb test. The same sized sparks can fly from either connection in my experience(when I kept at it wire heat let me know which for sure. Not good IMHO. I use a bulb test. Lionel has one of the best tutorial classes anywhere on phasing. A You-tube video How to "Phase" two or more transformers & why Era does not have a bearing on phasing it must be checked on all.

All original Postwar Lionel power cords were non-polarized, with both blades the same size. Replacing the cord with a polarized one would only allow the plug to be inserted one way, which could inhibit phasing the transformer with another. Other than that, I see no harm.

Using a grounded cord is another matter. There is no reason to use a grounded cord. Connecting the ground wire (green) in the wrong place could create an unsafe condition. DON'T DO IT.

I'm very glad that everything worked out for you. You had some great advice from some great people. Love this forum.

Gentlemen,

   Got to admit the ZW breakers do fail, but not very often, this is the 1st one I have heard of in a long time.  Fix her up and drive on!

PCRR/Dave

It is precisely because I have several phased transformers that I use polarized plugs.  When installing a replacement cord, I am careful to connect leads to preserve that phasing, and using the polarized plug assures that no metter how many times a transformer is unplugged, it will always be phased.

If I were to get a new transformer and phasing differed, I'd go inside the unit, verify that like old Lionels there is no reason for the way it's connected, and reverde the leads.

Bob, ignore the advice to alter the plug.  If you use multiple transformers, start a new thread on phasing.

I think Lionel recommended putting a spot of paint on one side of the plug to identify how to plug in their transformers while maintaining phasing.

no I don't have a part #, cant remember what I used. Think it was  a 10 amp breaker.

tested it by putting a screw driver across the tracks to short it out and the breaker "POPed" what seemed like before I even touch the rails. would let it reset and did that a couple of times. it always broke the circuit in quik fashion.

do what a friend of mine did, "jury rig it"!!!

he had an older model car with the little tube fuses.

he was driving home one night and the headlight fuse blew.

he didn't have any fuses with him, so he used the next best

thing he had with him that was about the same shape as that old style fuse,

a 22 cal. bullet. He placed the bullet in the fuse box, lights came on. He drove down the road awhile and BANG, the bullet went off and shot him in the knee.

State Trooper that pulled up had lots O questions. He recovered.

Well happy days are here again men.  I was working on the layout this morning and have now added back the lights on one inner zw circuit and 5 of 7 O22's on fixed voltage plugs on the other. So far the transformer is holding up like a champ. The seller agreed to refund me half of the breaker replacement fee which came to 13.75 for his share. He's happy to not get the thing back and have to pay another $30 to have me ship it back to him. All told the ZW has cost me about $170 delivered. Not bad if it stays healthy. So right now all electrical is being run off the ZW. Since I don't have two trains running on the same loops, and the outer loop is electrically isolated from the inner two, I don't think I am facing any phasing issues. It's working fine with its updated polarized plug. I did have to take another O22 off and replace it with one from my "yards" which I haven't opened yet. It was lighting sporadically. I looked in there and see that I must have damaged the fixed voltage pin inserting plugs over the last few weeks. I took all the Lionel plugs off and wired them with the blue butt joint connectors and those work great. That was a great suggestion from this forum. They stay on better than the Lionel plugs.  I noticed the local train guy looking at the blue plug kind of quizically when I took an O22 in to ask him about why it was causing derailments. (The slider seemed to me like its about 3/32" lower than the rest of the track...he said there was nothing to do about that). I'm pretty sure he was impressed, but he didn't say anything. As many years as he's been in his little shop, I don't think he had ever seen that before. We all can learn more no matter our age. This forum is totally awesome. Thanks again guys. Oh by the way I found out my neighbor does have a clamp ammeter so if I need to, I can run some tests.

Bob, phasing is only an issue if you have multiple transformers.  Using only the ZW, it is not an issue, but do always connect U to outside rails.