Testing circuit breaker...Stumped!

I have an older Lionel Type R transformer as my bench supply.  I bought some of the fast acting circuit breakers recommended here.  I have the breaker hooked up in series on the hot line.  In other words.....

 

transformer hot----> breaker--->screwdriver----->Transformer common.

 

I have placed two alligator clips across a screw driver to try and short the circuit and trip the breaker.  While the transformer lights dim and you can here it buzz more, the breaker never trips.

 

What am I doing wrong?

 

Breaker link 

 

http://www.newark.com/te-conne...mp;mckv=sDLTjEFeN_dc|pcrid|72064818035|plid||kword|w28-xq1a-7|match|p&CMP=KNC-GUSA-GEN-SKU-MDC&gclid=CIiI-YiorMgCFYdefgodAFsAtg

 

 

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RA

Original Post
Originally Posted by ADCX Rob:

7 amps is too much. The internal breaker will trip first, especially since these "R" models are known to have weakened/sensitive breakers w/ age(or it won't trip at all). The "R" transformer is rated for an output of about 3-3.5 amps at 24 volts.

Any idea how I can test the breaker and make it trip?  My main transformer is a postwar ZW but I kind of want to bench test the breaker some how.

 

I just want the thing to  trip if I have a derail short.

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RA

Originally Posted by TurtleLinez:

Any idea how I can test the breaker and make it trip?  My main transformer is a postwar ZW but I kind of want to bench test the breaker some how.

Connect the breaker to A-U of the ZW and crank it up.

 

If you want to see at what amperage the breaker trips, put an ammeter in line(series) with the breaker and raise the voltage more gradually watching the meter.

Rob

I have a 1941 Type R.  The internal breaker does not protect every combination of binding posts.  I used it for a bench supply also, having retired it when my parents gave me a ZW in early 50's.  I recently re-retired it, and went to an MTH Z500 for the bench.  It's adequate, cheap, and has a reliable breaker.

 

ON the ZW, do be aware that the internal breaker is in the line from one end of the secondary winding to the U terminals, so it would not protect against a short between any of the A-D terminals, which can occur is a train stops with rollers bridging a gap between power districts.  For complete protection, I'd put a 10-amp external breaker in the Line from U, and a 7 or 5 in the ABCD lines.

FWIW, you can normally use a considerably lower value thermal breaker than the maximum rating of the transformer.  For my test bench, I have a 2 amp breaker, and I've yet to have a normally operating locomotive on the rollers trip the breaker.

 

For tracks, I like something in the 6-7 amp range.  A 10 amp thermal breaker requires considerably more than 10 amps for a significant period of time to trip.

 

Here's a chart for the TE Connectivity Potter & Brumfield Relays W28 series, a very popular type that is used on a number of transformers.  If you look at the 3-20 amp models, for a 135% overload, it'll trip only after one hour!  That being the case, you have 10amp capability using the 7 amp breaker unless you have continuous power draw at the 10 amp range.  The 10 amp breaker won't trip for a loooooooong time with over 13 amps of current.

 

 

cb trip curve

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The Lionel PH180 breakers are nice and fast, one of the primary reasons I'm so high on that transformer.  They also have sort of a two-speed sensor where they recognize the difference between a gradual slight overload and a quick spike that indicates a short.

Given the breaker I have, how can I test it.  Will the 7 amp breaker I have on the track trip before my ZW breaker will?

 

Do I have the wrong size breaker?  All I want is for it to trip in derailments.  Some added or faster protection for the trains as compared to the ZW.

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RA

Almost any breaker 10 amps or less will open before the one in the ZW.  How many trains and lighted cars do you run on the circuit. A good rule of thumb is to use the smallest that handles the trains you run.

 

Among my layout's transformers are 2 old ZWs, each powering 2 TIU channels.  I use 5 amp breakers on these, which are adequate for running 2 trains each (smoke off). I have 2 more circuits powered by a Z4000, and on that I use a 7 amp because I frequently run 3 trains.

 

If you run one train, I'd drop to a 5.

Originally Posted by TurtleLinez:

Given the breaker I have, how can I test it.  Will the 7 amp breaker I have on the track trip before my ZW breaker will?

Test:

 

Connect the breaker to A-U of the ZW and crank it up.

 

If you want to see at what amperage the breaker trips, put an ammeter in line(series) with the breaker and raise the voltage more gradually watching the meter.

 

Originally Posted by TurtleLinez:

All I want is for it to trip in derailments.  Some added or faster protection for the trains as compared to the ZW.

This is a common misconception - the breakers were not / are not intended to protect the trains, they are to protect the transformer and wiring.

 

Rob

Originally Posted by RJR:

Almost any breaker 10 amps or less will open before the one in the ZW.  How many trains and lighted cars do you run on the circuit. A good rule of thumb is to use the smallest that handles the trains you run.

 

Among my layout's transformers are 2 old ZWs, each powering 2 TIU channels.  I use 5 amp breakers on these, which are adequate for running 2 trains each (smoke off). I have 2 more circuits powered by a Z4000, and on that I use a 7 amp because I frequently run 3 trains.

 

If you run one train, I'd drop to a 5.

Crap....OK I will lower the breaker.  I run one train.

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RA

Originally Posted by ADCX Rob:
Originally Posted by TurtleLinez:

Given the breaker I have, how can I test it.  Will the 7 amp breaker I have on the track trip before my ZW breaker will?

Test:

 

Connect the breaker to A-U of the ZW and crank it up.

 

If you want to see at what amperage the breaker trips, put an ammeter in line(series) with the breaker and raise the voltage more gradually watching the meter.

 

Originally Posted by TurtleLinez:

All I want is for it to trip in derailments.  Some added or faster protection for the trains as compared to the ZW.

This is a common misconception - the breakers were not / are not intended to protect the trains, they are to protect the transformer and wiring.

 

Ok thanks.  It looks like I need a 5 amp breaker as typically I only run one train.

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RA

They're cheap enough.  FYI, on a circuit powered by a Z4000, which has a fast breaker, on a derailment the 5-amp usually opens before the Z4000.  I wanted to protect the fine gauge wiring in cars, and pickup roller springs, from overheating.

I have the zw hooked up.  With the 7 amp breaker in series.  I put a screw driver across the rails.  I get a spark.  However the breaker never trips.  I am only holding the screw driver down for a second or so for fear of frying the zw.

 

It seems at this point that I have no circuit protection.  I am trying to have a modern breaker trip before the old zw one.

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RA

Originally Posted by gunrunnerjohn:

A brief short, especially with any resistance in the loop, won't trip a thermal breaker. 

How long?  Do 5 seconds then 10 then 15....I mean if I smell burning Bakelite this would be kind of dumb.

 

I had a bad component from an order recently so I just want to hear the breaker trip.

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RA

If you short it right at the breaker, and you have good connections from the breaker to the transformer, you should get a pretty quick trip, within a couple of seconds.  If you have sized the breaker correctly, doing that shouldn't damage the wiring or transformer.

 

Once you connect to the track, and run through a bunch of track joints, you'd be surprised how the resistance adds up.

 

Originally Posted by TurtleLinez:

I have the zw hooked up.  With the 7 amp breaker in series.  I put a screw driver across the rails.  I get a spark.  However the breaker never trips.  I am only holding the screw driver down for a second or so for fear of frying the zw.

 

It seems at this point that I have no circuit protection.  I am trying to have a modern breaker trip before the old zw one.

That's not long enough for a test. Lionel specified something like 10-14 seconds for the ZW. Why are you testing with track and wiring, & without an ammeter? We have no way to see what resistance is in your circuit... depending on the wire, it may never trip.

 

To test the breaker(s), connect the breaker to A-U of the ZW and crank it up.

 

If you want to see at what amperage the breaker trips, put an ammeter in line(series) with the breaker and raise the voltage more gradually watching the meter.

Rob

Originally Posted by ADCX Rob:
Originally Posted by TurtleLinez:

I have the zw hooked up.  With the 7 amp breaker in series.  I put a screw driver across the rails.  I get a spark.  However the breaker never trips.  I am only holding the screw driver down for a second or so for fear of frying the zw.

 

It seems at this point that I have no circuit protection.  I am trying to have a modern breaker trip before the old zw one.

That's not long enough for a test. Lionel specified something like 10-14 seconds for the ZW. Why are you testing with track and wiring, & without an ammeter? We have no way to see what resistance is in your circuit... depending on the wire, it may never trip.

 

To test the breaker(s), connect the breaker to A-U of the ZW and crank it up.

 

If you want to see at what amperage the breaker trips, put an ammeter in line(series) with the breaker and raise the voltage more gradually watching the meter.

The breaker is coming off the terminals.  I just put some track in there after the circuit.  Figured that is a more real world test.  The 7 amp breaker never tripped.  However at full bore the zw only pulled 5 amps.  So I guess I need more of a load?

 

I am using test leads so the wire is probable 20 gauge.  My layout runs on 16 gauge.  But I don't pull a lot of amps.  A short would though.  That's why I want the breaker.

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RA

Originally Posted by TurtleLinez:
The breaker is coming off the terminals.  I just put some track in there after the circuit.  Figured that is a more real world test.  The 7 amp breaker never tripped.  However at full bore the zw only pulled 5 amps.  So I guess I need more of a load?

 

I am using test leads so the wire is probable 20 gauge.  My layout runs on 16 gauge.  But I don't pull a lot of amps.  A short would though.  That's why I want the breaker.

Too much resistance in the circuit - the breaker will never trip.  Your test leads are 100 watt heater wires in this circuit - way too small for a 7 amp breaker.

Rob

I am a fan of the PW ZW transformers and recently I have added Eaton Miniature In Line Circuit breakers, part number WMZS1C03. They are rated for 3 amps and work very efficiently. These have replaced my 7amp fast blow glass auto fuses.

 

You can get then online anywhere from $9.00 to $18.00 dollars each.

 

I need to do more studying on these TVS items.

 

jeff

I was wondering about whether it is wirth the effort to test circuit breakers on Lionel transformers.  I just had an inquiry about that from a buyer to whom I sold a KW.  So I did  query on this forum and found this long discussion from several years ago.  

I have a few follow-up questions.

It seems like a spectacular short is needed to test the breaker on a ZW.  I don't want to play with making a 10 amp short.

My conclusion is that testing isn't worth the trouble.  When I sell a transformer on Ebay, I note that I have no way of testing the breaker.

I don't use circuit breakers at all on my layout, which si a 7x11 teswt loop and a few sidings.  IF I do have a short, not unusual, I can hear, see or smell it and occasionally my RW breaker trips.

I'd be interested in any comments that those with more experience than me may have about my observations

Turtle,

   You are making to much of this, use the ZW and use 5-7 Amp Resettable Breakers for your test.  In fact I use 10 Amp Breakers to safe guard my layout and have never had a problem, they pop when they need to, and keep my layout safe.  If I had to do it again I would keep the 7 Ampers I gave away, instead of the 10's I kept.

Your problem right now with the test, is your transformer is to small.

PCRR/Dave

 

Never worry about what other people think, be strong and walk in the way of the Lord.

I agree with PCRR/Dave.  Not worth checking the internal breakers, which weren't much good even when new, but DO USE external breakers.  Your technique on your layout is not conducive to safe operation, but heck, it's your house.

 

 

Anybody can perform a basic circuit breaker test by putting the ZW on a switched outlet (off). Set one pair of terminals to max voltage, and put a heavy gauge wire across the terminals.
Turn the power on and time how long it takes for the breaker to trip.
Compare your results with the tables in the test bench instructions that can be found in the Lionel service manual. (use the tables to also determine how long to wait before interrupting the test)

As far as keeping layouts safe: that is not what the internal breaker in a large transformer is supposed to do. It is there to protect the transformer itself. Use external circuit protection to protect your layout wiring and trains. Don't put the external breaker on the common leg. Put one breaker on each "Hot" terminal that is in use: "A", "B", "C", and "D".  And if your trains have electronics, use TVS devices.

When servicing a Lionel transformer, don't forget to:
Check the cord
Check the rollers
Check for A.C. leakage
Make certain the whistle control(s) operate smoothly and do not hang up. *

I guess we all have our own standards. I would not use or sell a transformer that wasn't 100 percent in proper operating condition, as sold by the manufacturer, including the breaker.

* - had a ZW on my bench that had the whistle control hang up due to a broken centering spring.  It created a short that was not protected by the internal breaker. The owner reported that lots of smoke was generated, and I could see evidence of parts like one of the the roller arms being overheated.

C.W. Burfle
mlaughlinnyc posted:
My conclusion is that testing isn't worth the trouble.  When I sell a transformer on Ebay, I note that I have no way of testing the breaker.

My conclusion would be that your conclusion is wrong, at least IMO.

CW, my breakers are wired exactly as you describe, BUT, even though I don't do it, there should also be a breaker in the common.  If, for purpose of discussion, the max current that should be allowed in a ZW is 10 amp, and you have 7-amp breakers in each of the 4 outputs, then one could have up to 28 amps flowing through a portion of the windings.  Just a thought.

gunrunnerjohn posted:
mlaughlinnyc posted:
My conclusion is that testing isn't worth the trouble.  When I sell a transformer on Ebay, I note that I have no way of testing the breaker.

My conclusion would be that your conclusion is wrong, at least IMO.

What would you suggest that I do with, for example, a KW, ZW or 1033 ?

mlaughlinnyc posted:
gunrunnerjohn posted:
mlaughlinnyc posted:
My conclusion is that testing isn't worth the trouble.  When I sell a transformer on Ebay, I note that I have no way of testing the breaker.

My conclusion would be that your conclusion is wrong, at least IMO.

What would you suggest that I do with, for example, a KW, ZW or 1033 ?

Sorry I threw out that question before I noticed the other answers.  Thanks to all who replied to my question - you've given me some good stuff to think about

RJR posted:

CW, my breakers are wired exactly as you describe, BUT, even though I don't do it, there should also be a breaker in the common.  If, for purpose of discussion, the max current that should be allowed in a ZW is 10 amp, and you have 7-amp breakers in each of the 4 outputs, then one could have up to 28 amps flowing through a portion of the windings.  Just a thought.

Any transformer that crosses my bench has a properly working internal breaker, hence there is no need for an external breaker on the common.

Having a fifth breaker on the common side wouldn't hurt anything. The important point is that having a single external breaker on the common side is not a good solution because it is very easy to accidentally create an unprotected short between two "hot" terminals.

C.W. Burfle

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