Wiring and breaker problems

[Gray Cat]

Here's one for our more learned layout wiring experts.. I have a 5 by 9' layout of three rail PW Flyer.. when I originally wired it what I did was drill out the supports under the table length wise and install bare copper ground wire (the kind used as a ground on a service panel, I think it's 10 or 8 gauge), to the ends of this I soldered on stranded copper lamp cord (16 gauge) and this is in turn hooked to the transformer (275 W ZW). These two buss's were to be used as positive and negative for all the lighting on the layout. However I'm running into a problem where after about 10 minutes of running the breaker on the ZW pops. I've systematically eliminated everything from the system one by one and everything points to the lighting system as the problem. The lengths of buss are about 6' long and the positive and negatives of each lighted device are twisted around the correct buss wire.. Now there are some connections that are not as of yet soldered, but they have a wrap of at least three turns and what looks like a good connection as the lights are all working properly. I have checked and double checked the accessories to make sure they have good wiring and all looks well..

 

Any thoughts? Comments on the best way to wire up lighting? This is a nagging problem that I haven't figured out yet. I do plan on soldering all the connections tonight if I get time.. could the unsoldered connections be causing just enough resistance to pop the ZW after  about 10 minutes? IS that Buss wire heavy enough to carry that load? I would have thought it was..

 

Thanks,

Pat

[TrainLarry]

  It sounds as if the circuit breaker in the ZW may be a little weak and tripping at a lower than rated current, or there is a high resistance short somewhere, possibly a bad track section. Disconnect all accessories,  leave just the track hooked up, and turn up the voltage. Run your hand across every track connection and lockon connection. A bad connection will feel hot. Do this also to all your undertable connections.

  If operating your lights alone, without any trains, trips the breaker, you may have a weak circuit breaker. Replacements are not expensive, and may solve your problem if everything else is in good shape, and there are no obvious overloads.

Larry

[balidas]

How many lights are hooked up? Is the ZW powering the entire layout? Maybe it's just being overloaded.

[lionelsoni]

A ZW's circuit breaker should trip at 15 amperes.  Your 10 AWG is heavy enough for twice that, not even taking into account that you're feeding it from both ends.  However, the 16 AWG is good only for 10 amperes.  You should go up to 14 AWG.

Poor connections or undersized wire may heat up; but they can only reduce the load on the transformer, not increase it.  Either your circuit breaker is tripping at too low a current or you are actually exceeding the 15-ampere rating of the transformer.  Add up the currents from all your loads to see whether that is the case. 

(There is no such thing as "positive" and "negative" sides of an alternating current circuit.  One side of the circuit can be considered the "common".  That is usually the wire from the U terminals of the ZW to the outside rails.  "PW" could be prewar or postwar, except that the only American Flyer with 3 rails is prewar.  "Buss" means "kiss"; "bus" in the sense you mean has only one "s".)

[Gray Cat]

At first I was wondering about the circuit breaker on the ZW so I pulled another known good one off the shelf and hooked it up.. same same.

I went around all tracks, both the inside loop and outside loop with a meter. I took readings everywhere.. making sure no track was shorting out. I also have each loop fed with lamp cord with a 2" length soldered directly to the underside of a section of track and then I have added tie points around the loops to ensure no slow running trains. Operating lights alone does not trip the breaker. Train alone, all ok, lights and train.. pop.

[Gray Cat]

balidas

How many lights are hooked up? Is the ZW powering the entire layout? Maybe it's just being overloaded.

 

at maximum there were three Marx spotlight towers (total of 6 bulbs), one Prewar AF station (2 bulbs), one marx switch tower (1 bulb), Prewar Water tank (1 bulb) two loops of track (two trains), including 4 AF switchs adding two bulbs each (8 bulbs). So if I do my math right that's 18 bulbs and two trains.. there is also a Whistle Billboard but that's not on all the time.

I know have two ZW's in place one is running inside loop and lighting only.. and that pops after about 10 minutes of running.

[Gray Cat]

Quote> A ZW's circuit breaker should trip at 15 amperes.  Your 10 AWG is heavy enough for twice that, not even taking into account that you're feeding it from both ends.  However, the 16 AWG is good only for 10 amperes.  You should go up to 14 AWG.

Poor connections or undersized wire may heat up; but they can only reduce the load on the transformer, not increase it.  Either your circuit breaker is tripping at too low a current or you are actually exceeding the 15-ampere rating of the transformer.  Add up the currents from all your loads to see whether that is the case. 

(There is no such thing as "positive" and "negative" sides of an alternating current circuit.  One side of the circuit can be considered the "common".  That is usually the wire from the U terminals of the ZW to the outside rails.  "PW" could be prewar or postwar, except that the only American Flyer with 3 rails is prewar.  "Buss" means "kiss"; "bus" in the sense you mean has only one "s".) < quote

 

I kinda thought that I had enough wire. I am only feeding the 10 awg on one end but feeding both with about 18" of 14 wire stranded

 

Of course I know about the positive and negative.. mea culpa, I should have said line/neutral or common.

The PW is personal lingo between me and a friend that talk trains.. to me any Flyer after the war is S so when referring to it among friends I always abbreviate PW.. I'll try to be more clear when I post questions in a public forum..

Buss, bus, 260 240 whatever it takes! Where's the spell check button!

It shoud be Buss anyway.. this thing has the kiss of death as it's killin' me.

[lionelsoni]

You had said above that you were using 16 AWG, but if it's 14, that's fine.

I didn't know that you were running trains with the same transformer.  The total transformer current goes through the circuit breaker; so I think it's likely that it all is adding up to more than 15 amperes.  Your experiment with swapping transformers seems to show that pretty conclusively.

If you did want to calculate the lamp current, just knowing how many lamps gives only the fuzziest idea of the current that they're drawing.  You need to find out what the lamp types are and what voltage you're running them at to figure out what current they're drawing.  Every lamp type has a specified current that it draws at a particular voltage.  For example, the very common number 53 lamp draws 120 milliamperes at 14.4 volts.  Then, if you're running it at another voltage, you apply a rule of thumb that the current varies as the .55 power of voltage, to calculate the actual current.  If you want and can supply the lamp numbers and voltage, I would do that for you, but I don't think there's any point.

 

[Gray Cat]

Thanks Bob, I'll keep digging to see if I can figure this out..

I am running the lamps at about 13 volts.

 

It just seemed to me that the ZW being pretty much THEE flagship transformer that running two trains and a layout's worth of lights would be a walk in the park. There is always the chance the both of the circuit breakers are weak.. these transformers are OLD..

[TrainLarry]

 If you have a volt/amp meter, you may need to directly measure the total current consumption of your trains and lights operating at the same time. This will tell you if you are overloading the transformer, or if you have a weak circuit breaker.

Larry

[balidas]

From what I've learned recently, even tho the ZW is the flagship transformer, it is limited. It's advertised as 275 watts but the output is actually 180 watts, for one throttle, if you use two throttles then there is 90 watts per throttle, and using four throttles you have only 45 watts each.

[lionelsoni]

It's true that the rating that Lionel put on those transformers was power in, not out; and that the ZW is good for only 180 watts out.  This corresponds to 15 amperes at 12 volts, which is consistent with the circuit breaker's rating under the assumption of a typical 12-volt setting.

But you can always draw the full 15 amperes (180 watts at 12 volts) from any one of the outputs, regardless of how many are in use, as long as the total current does not exceed 15 amperes.  The total rating is not divided equally among the 4 outputs.

(Note that very substantial momentary overloads may not hurt the transformer at all.  The thermal circuit breaker that it uses models this capability well, not tripping until the overload has persisted long enough to be harmful.  This is why adding other, faster types of circuit breakers or fuses is not such a good idea.)

[webenda]

Gray Cat,

How many amps are being drawn when the breaker on the ZW pops?

Eighteen lamps might draw four and a half amps. My Willaims BL-2 draws two and a half amps pulling a six car train up a one percent grade. Two of the same train would draw five amps. Maximum current draw, lamps plus two trains, should be nine and a half amps.

How many amps is your set-up drawing?

Here is a bit of philosophy about making measurements:

"In physical science the first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be."

--Lord Kelvin--

[Gray Cat]

Here are my latest findings.

I went through each of the lighting fixtures, one by one. I did find one Marx yard light tower with what looked like a bit of bare wire touching the base. I'm using two strand bell wire from my bus lines underneath to each individual light accessory. I used an auto stripper to loosen the brown outer sheathing on the bell wire and it looks like it bit in a little and bared just a strip of wire on the back side where it couldn't be seen. This was laying against the base since I had the wires stretched between the posts to keep wiring as neat as possible. It is possible that this was causing enough of a "leak" to strain the transformer, but I can't be sure. I also removed a Prewar Flyertown Station with original cloth covered wire.. I ran the train and lights for about 45 minutes with no mishap.. I then added a few more lighted accessories one at a time. When I added the final Wayside station the breaker did again pop. At this time I took amp readings on everything. The train was drawing 2.40 at the transformer and the lighting was drawing 1.80 again at the  transformer. At this time the only conclusion I can come to is that the original breaker is now weak from the mulitple times it did pop off. This is also an original breaker so it's probably seen better days. I'm planning on replacing the breakers on both my ZW's and try it again.. perhaps this time putting a 5 amp breaker on each cab before the transformer

[webenda]

Thank you for current readings Gray Cat.

I imagine if you measured current at the "U" terminal (the terminal the breaker is connected to) it would read 4.2 Amps AC.

Breakers do not get weak from multiple activations, so your problem baffles me.

[Gray Cat]

webenda

Thank you for current readings Gray Cat.

I imagine if you measured current at the "U" terminal (the terminal the breaker is connected to) it would read 4.2 Amps AC.

Breakers do not get weak from multiple activations, so your problem baffles me.

 

Those readings total would be accurate.. and 4.2 amps should not cause a 15a breaker to trip..

I was under the impression though that the bi metallic breaker in the ZW after repeated heatings from overload could become weakened and trip under lesser load. I would love to hear more commentary on that subject.

Regarding the layout wiring problem, as of this morning I had a 23 minute uninterrupted run of trains and lighting before shutting it off to get ready for work. The breaker did not trip. At this time I can only conclude that the problem was either that little bit of slightly bare wire that "might" have been touching the base of the yard light OR the Flyertown Station with original wiring. ( I have heard of light socket phenolic insulator failure).. While neither of these items presented a dead short, they are both suspect. Unfortunately I always believe that something isn't really repaired until you can say what was broken., ugh

[gunrunnerjohn]

Contrary to opinions stated here, a CB does have a limited lifetime.  Just read any spec sheet for a circuit breaker.  The life cycles come into play when the breaker trips under a short circuit, using them as a switch isn't as hard on them.

[webenda]

Correct gunrunnerjohn. I am happy you bring life cycle of thermal circuit breakers up. You and Gray Cat encourage me to get techinical.

Generic Thermal Auto Reset Circuit Breaker Electrical Specifications:

• Rating: 15.0 Amp

• Resistance: 0.010 Ohms

• Calibration: Will continuously carry 100% of rating, may trip between 101% and 144%, but must trip at 145% of rating at +25°C

• Maximum Operating Voltages: 50 VDC; 250 VAC, @ 50/60 Hz

• Interrupt Capacity: 2,000 Amps at 50 VDC, 1,000 Amps at 250 VAC.

• Endurance Cycling: Over 5,000 cycles at 100% of rated load, over 1,000 to 2,000 cycles at 200% of rated load

Reference:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=075-154&utm_source=msn&utm_medium=cpc&utm_term=nte%20r58%2015a&utm_campaign=B_New_MFG_KLMN_Products_Exact&utm_group=075-154_Exact

http://www.mechprod.com/engineering-resources/overcurrent-physical-characteristics-1-4.html

http://www.sensata.com/download/klixon-circuit-breaker-thermal-PS.pdf

From Gray Cat's description we learn that he did not let the breaker cycle 1,000 to 2,000 times. Also the overload current was not 200% or higher, judging from the time it took to trip the circuit breaker. That means we can consider the upper life cycle specification of over 5,000 cycles.

It is not the bimetallic strip that wears out (or gets weak) in a thermal circuit breaker. It is the contact points. When the circuit opens there is an arc that forms at the opening contacts. The arc pits and heats the contacts. Heat accelerates oxidation of the contact surface. In the case of a ZW, the contacts have had many years to build up an oxide layer at room temperature. Once a poor (high resistance) contact forms, the contacts themselves can generate enough heat to make the thermal circuit breaker open below specified current.

Cycling a thermal circuit breaker can be a good thing.

Mechanical Cleaning

When the contacts are closing, the metal surfaces making contact with each other can cause deformation and mechanical destruction of thin oxide layers.

Electrical Cleaning

Strange as it seems, that troublesome opening arc can clean old oxidized contacts. The arc, upon contact opening, can blow through oxide layers as well as disintegrate other contaminants or particles in the vicinity of the contact point, resulting in restoring the thermal circuit breaker to is its calibration specification.

Reference:

http://www.w8ji.com/relay_cleaning_and_life.htm

http://relays.te.com/schrack/pdf/C0_v4bg_4.pdf

[Gray Cat]

After testing all I could and reading everything written here and elsewhere I pretty much believe that the Circuit Breakers have exceeded their useful life. During the time I was diagnosing or rather trying to track down the problem, my ZW went off on overload at least a few dozen times. Considering that it is almost 60 years old, there is a good chance that all things considered such as normal oxidation and the pitting and resultant high resistance/heat, that the circuit breaker is shot. I can run the trains with lights on for 20-30 minute stretches now with no trouble and then out of the clear blue.. red light!.. Based on amp readings and inspection of all electrical parts I can come to no other conclusion at this time than that the Circuit Breaker needs to be replaced. I'll be doing that this weekend if I can get the parts.. I was also thinking in the meantime as an additional test to put a pair of fuse holders in line with the lighting output on C and the train output on A.. starting with lower amp ratings like a 2 amp and gradually increasing them. My thought is this would rule out any slow leak/short for certain as if there was a short it would/should take out a fuse of lighter than 15 amp rating. If the fuses stay and the breaker pops wouldn't this indicate the conditions mentioned of a corroded point set on the breaker or otherwise compromised breaker

[webenda]

"I can come to no other conclusion at this time than that the Circuit Breaker needs to be replaced."

Same conclusion here.

[Gray Cat]

FOLLOW UP:

After the final conclusion, I picked up a pair of brand new circuit breakers for both ZW's I'm using.. at this time I'm happy to report that they are now operating at the powerhouses I always heard they were reputed to be..

These original bi metallic disc breakers do not look that substantial, so it's not really a surprise they failed. One of the breakers showed evidence of heat cracking on the plastic/phenolic mounting plate.

Thanks for all the conversation and input!

[webenda]

That's great!

Thank you for leading this thread Gray Cat. We just witnessed a fine example of using team work to solve a problem. I think everyone's input was valuable.