1950's Zw Transformer

[4 8 8 4]

 Curious thing about this thing is no matter how many trains i run with this thing after about 3 minutes it cuts off. 

I was told once by someone at a show that it might be a breaker going bad in it but i can not find it.  but was probably looking at it

if you can help i would appreciate it 

bobbie

[EIS2]

Locate the two wires that come off the strip that ties the four top common 'U' terminals together.  One wire will go to a resistor.  The other wire will go to the circuit breaker.

Earl

[4 8 8 4]

 Thank you

do you know where or what i can replace the breaker with

 

[lionelsoni]

If you can't get or don't want to go to the trouble to get an exact replacement, you can use a 15-ampere automatically-resetting automotive circuit breaker, from practically any auto parts store.

Since Lionel provided no protection against the fault current that can flow when any two of the A, B, C, or D outputs are connected together, you can add this protection for your transformer and layout wiring by also inserting breakers in series with those four outputs.  These could also be rated at 15 amperes; but you might want to use 10 instead (or even 5 depending on how old and big your trains are), since it is very unlikely that one train will draw more than that much current.

[Civil War]

 

lionelsoni

Since Lionel provided no protection against the fault current that can flow when any two of the A, B, C, or D outputs are connected together, you can add this protection for your transformer and layout wiring by also inserting breakers in series with those four outputs. 

 

Can these be added externally to these outputs?

 

[lionelsoni]

Yes.  External or internal, doesn't matter.

[EIS2]

 If you use a common ground, you only need one circuit breaker on the ground circuit ('U').  That is exactly what the ZW does on the inside of the transformer.  All of the grounds are tied together on the other side of the 'U' terminals.

Earl

[lionelsoni]

If you set two of the ZW outputs to different voltages, then connect them together (as people all too often do), you can easily destroy your ZW.  The fault current that will flow will not flow through the single circuit breaker and will not trip it.  Circuit breakers on the individual outputs will protect the transformer (and your layout wiring).  The common circuit breaker is still useful, since it limits the total current drawn by the 4 outputs to a safe value, which individual breakers rated at reasonable currents will not do.

[cwburfle]

In addition to the reasons Bob gave for protecting the individual outputs on ZW (I have witnessed a destroyed ZW caused by a short between two outputs, so it isn't just theory), one should also remember that the breaker inside the ZW is only designed to protect the transformer itself. I have seen a ZW melt the insulation off a layout's wiring  before tripping the breaker. I was also burned by the handrail of a derailed loco that happened to be creating a short on a layout with only the internal breaker for protection. I like to use postwar Lionel #91 electromagnetic breakers to protect each output. They are adjustable, with a manual reset button that lights up when the breaker trips. They can usually be found for somewhere around $20 each.

[4 8 8 4]

 thanks for all the input guys but i am not sure what is actually wrong with this zw

it will only run trains including only one on one throttle for a short time before it shows a short and cuts power to the rails.  

I have checked everything but cannot figure out what the problem is.  Is there anyone out there who has had this problem before and found a cure to it.  as i said earlier one person told me that it was the internal breaker that needed replaced

any help 

thanks in advance 

bobbie

 

[bfskinner]

I think the answer, plus some useful information by lionelsoni and others, is in the thread already. The most likely problem is a malfunctioning circuit breaker. Often the easiert way to diagnose something is to replace the suspect part and see whether that fixes it. You can do that "permanently" or temporarily as a diagnostic test.

You doubtless meant that no matter how few trains you run the breaker pops. With enough load on the transformer it SHOULD pop -- that's its job. We don't know what the total load is on the device, and without this info it is difficult to see what's going on. What happens when you disconnect everything from the transformer except the one track, with no accessories, and only the one loco?

You could have a malfunctioning breaker, a "stealth fault" on the layout somewhere, or just "the straw that sends the camel to its knees."

 

[lionelsoni]

To replace the circuit breaker temporarily, as bf suggests, you can solder or clip a jumper across the internal breaker, then wire the substitute 15-ampere breaker externally in series with the U connections to your transformer.  If that fixes the problem, then you can perform the circuit-breaker transplant.

[4 8 8 4]

 Thank you i will try that tomorrow and let you guys know how it came out

Bobbie

[4 8 8 4]

 Guys all your help was useful and it worked

The Transformer is working well I am going to replace the breaker as soon as the hobby shop can get one I am also going to get the auto breakers that you reccomended.  I am not sure what amperage to get though I run MTH Steamers/ K-Line Big Boy/ Williams Steamers and Electrics/ and a 2046 Hudson.  so guys help me finish this up.  Tell me what i should put in between the Transformer and the Track.

[lionelsoni]

Fifteen amperes, the same as the built-in circuit breaker, would protect the transformer adequately.  However, I suggest 10 instead, since any individual train is very unlikely to need that much.  The heating effect of current goes as the square of the current; so a 10-ampere fault does less than half the damage of a 15-ampere one.

[4 8 8 4]

 what is meant by a 10 amp fault

i do not understand are you referring to a short

 

[lionelsoni]

A fault current is any current that flows when it shouldn't.  It could be the result of a short circuit, or connecting too many or too heavy a load to the transformer.  The idea is that, if a circuit never needs to supply more than 10 amperes to its normal load, then it can be protected by a 10-ampere circuit breaker, even though it could, like a ZW, supply 15 amperes.  When an abnormal current--a fault current--greater than 10 amperes is drawn, the circuit breaker will trip, stopping the heating of the transformer and wiring at a level half of what would have been reached with a 15-ampere breaker.

Note that, even though the individual outputs of a ZW might be protected at 10 amperes, the ZW as a whole can still supply a total of 15 amperes from all of its outputs.  Since each of the four outputs could individually supply 10 amperes, the sum would be 40 amperes if they were all fully loaded.  That is why you should retain the 15-ampere breaker built into the transformer's common.

[4 8 8 4]

 ahhh thanks for the explanation

 

[Civil War]

 I have been following this thread as there is some very interesting tips from Bob. In the latest issue of CTT on page 82 is an ad from Scotts Odds and Ends for a surge protector but when I went to his web site,  http://www.scottsodds-n-ends.com/circuit_breakers.htm  I found an interesting looking device that has four breakers and is available in 10, 15 or 20 amp. This looks like something that could be very helpful and is priced very reasonably at about 20 bucks plus shipping. I would like others opininons of the usefull ness of this item. It looks to be very compact and neat in appearance.

 

[lionelsoni]

I personally prefer the variety that resets automatically, like the original equipment, installed inside the transformer case; but that looks like a reasonable product to me for those who like a non-resetting breaker.

As for their surge "supressors" (sic), I wouldn't do it that way.  They propose connecting a TVS from each line to ground, even though the transformer secondaries are invariably floating.  I think a single TVS per circuit, across the circuit itself (e.g., A to U, B to U, etc.) would be more effective and cheaper.  Their 4-circuit box could actually be used for 8 circuits in this way, with the "ground" terminal connected to layout common instead of ground, rather than running the common redundantly through the box 4 times.  But, in any case, TVSs are so cheap and small that it makes much more sense to me to buy a handful and install them at the transformers or the track.

By the way, what they describe as "spade terminals" appear actually to be male quick-connect or "Faston" connectors.

[4 8 8 4]

 LIonelsoni in Laymens terms this means what

are the surge suppressors good or bad and are they something that i might need considering i am running some MTH protosound 2 Steam Engines and 1 Diesel on Conventional Mode Standard Transformers.  I power this layout Track by Track with 13 Seperate loops seperated by 13 seperate throttles one Throttle per loop.  This ZW that started this thread is one of two that i use all 4 throttles on each one to power and control 8 of the 13 loops.  With this stated do i need to do something else to help protect the Electronics in the MTH Engines or for safety to avoid a fire or anything else. 

Thanks again all you guys been wonderful in helping me get this thing fixed and improving the layout

Bobbie

[lionelsoni]

To protect the electronics in the locomotives that have electronics, put a TVS between the center rail and the outside rails, at the track, at the transformer, or anywhere in-between.  To protect the wiring and the transformers, put a thermal circuit breaker in series with the center rail.  So here is the wiring:

For each track,

Connect transformer terminal U to the outside rails and to one terminal of the TVS.

Connect transformer terminal A to one terminal of the circuit breaker.

Connect the other terminal of the circuit breaker to the other terminal of the TVS and to the center rail.

Repeat for each of the other tracks, each with its own circuit breaker and TVS.

[ChiefEagles]

Follow Bob's instructions and you can feel safe.  I followed them and now I don't worry.  He knows his "stuff".

[4 8 8 4]

 Thank you all I am sorry that i have been pestering you guys about all this but you guys rock

Thanks ever so much for helping me out 

Bobbie

[4 8 8 4]

 one last question the left handle on my zw that we just fixed does not shut all the way off is there a way to adjust it so that it shuts off