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@Don Baird posted:

I’m ready to install fuses on my O gauge layout   Am I right to assume that they go on the bus lines A, B, C, & D, but not the common bus line (U)?  on my ZW. I’m using 3 terminals for trains.

Correct.  You may also want to see basic circuit protection at "Circuit Protection for Toy Trains".

That's where I shared my protection on a very large layout.

Don, actually, installing a fuse in the common would provide better protection for the ancient PW Type Z/Zw transformer, as you can limit the current draw to 10 amps. Do note that all U terminals are connected internally, so you can use one as common for all circuits.  Having said that, the terminals are riveted to a common internal buss, and over the decades these connections may have deteriorated.

I also recommend using breakers rather than fuses.  The latter cost to much, as they'll blow on every derailment.  In a recent thread GRJ has piinted to a source for magnetic breakers.  I currentlyuse thermal breakers, which are slower and cheaper, but am considering whether to switch to the magnetics GRJ recommends..

RJR, this string is very confusing to me, but your comment seems to be at my level. Let me tell you where I’m coming from

in a previous chain I posted questions about my Christmas trains - two trains circling the tree on two circles of fastrack powered by my ZW.  One of the power lines and the carpet melted presumably because of my grand children’s derailments. I replaced the badly worn power lines with 16 gauge for the remainder of the season   I also decided to add some precautions to the permanent layout I’m building using tubular track, my ZW, and and a 1032.
So, I decided some kind of fuses or circuit breaker. Your answer to my question was unexpected and simple if I understand it. Put a circuit breaker on the common bus - U on the ZW. I had assumed it would be a 10 amp breaker on terminals A, B, & D for the three trains and a lower amp breaker for C. Tell me if there’s anything right about that.

with the 1032 I am using variable power  terminals U & B for the trolley. (U to the center rail).  Fixed power from B & C powers some accessories on the trolley lines and is converted to DC for a timer relay to control the stops & starts on the trolley line.

where do the circuit breakers go?

Don, I'll answer your last question first.  Breakers and fuses should always be on the transformer outputs, so they protect everything downstream.

A fuse or breaker in the U circuit has one purpose, to protect the transformer.  A postwar ZW shouldn't be subject to more than 10 amps.  FYI, the ZW internal breaker is in the U circuit, but is very slow acting. It provides no protection if there is a short between any of the ABCorD outputs, which is possible.

A current of less than 10 amps can cause considerable heating on the layout.  Breakers or fuses should also be put in each of the output circuits to protect the layout.    They should have the lowest amp rating that will operate your trains, which is usually less than 10 amps. On my layout, I run 6 TIU channels.  Some channels control areas where probably not more than 1 or occasionally 2 trains will be moving at once, such as yards.  These get 5 amp breakers.  Mainlines where I might have 3 locos running get 7.5 amps.  But I do not turn smoke on.

No fuse or thermal breaker opens immediately upon the current being exceeded.  There is a lag while the thermal elements heat up.  By using smaller amperage breakers, they open sooner on a short.  In another thread, Gunnrunner John mentioned certain magnetic breakers available from Digikey.  Magnetic breakers should open as soon as the rating is exceeded.  Electronic breakers, such as in the Lionel PH-180 Powerhouse,  also open upon exceeding the rating.  I am considering replacing my thermal breakers with magnetics, but have some higher priority matters to deal with.

FYI, I use Blue Sea marine push button breakers, available on-line from Defender Marine.  They are in the $5-$6 range and have worked well.

Hope this helps.

RJR

I don't know what the wattage rating is for that transformer, but I'm sure less than 10 amps is required.  For those old transformers:  Take the wattage rating; multiply times 0.75; divide the result by the maximum voltage the transformer can put out.  The result is the maximum continuous amperage.   Ideally, use that as a maximum rating on the U; on the others, that or some lesser capacity depending on the level of protection you want to afford your wiring and devices.

RJR

The 1032 is a 75 watt transformer generating 115 volts. With U as the hot shoe the results are:

AU 5-16 volts variable

BU 0-11 volts variable.    Others:

AB 5 volts fixed

BC  11 volts fixed

(C  16 volts ?)

I am using UB Variable to power trolley & BC for conversion to DC timer and to provide auxiliary power to accessories

Your formula:  75 (watts) x .75 = 56.25 divided by (16 or 155 volts) equals 3.5 or 0.4 continuous amperage.  Can that possibly be correct?

And even if it is correct, what does that mean for U, B, & C?  
Do I even need to worry when all that is connected is a cheap MTH trolley, three 153IRS and a few accessories (crossing signals, station lights)  

The transformer has a built in breaker to protect itself.

@Don Baird posted:

RJR

The 1032 is a 75 watt transformer generating 115 volts...

The transformer has a built in breaker to protect itself.

The 1032 internal breaker is rated to trip on A-U in 9-35 seconds into .2 ohms , if that will help you.

The breaker on the 1032 is to protect the transformer.

@Don Baird posted:
(C  16 volts ?)

A-C is 16 volts fixed.  "A" is common on the 1032 and has the breaker in it's feed(except in relation to B), C-U is 11-0 volts(yes, backwards), but like A-B, there is no breaker protection.

Last edited by ADCX Rob

3.5 amps would be the max continuous amps, aggregate for the transformer.  I don't know where you got the 155 or 0.4 figures.  115 volts is the input from the wall receptacle; it is not something generated by the transformer.

FYI, the 75% continuous rating was given by Lionel itself in its Model Railroading paperback back in the 50's/60s.    Also, the breakers in those old postwar transformers were not particularly good.  I will leave it to others to comment of the maximum continuous rating for modern transformers.

A handy gadget to have is a cheap AC ammeter.  You can ascertain the draw of each device.

Googling, I dug out the section of the Greenberg repair manual covering the 1032, including the schematic.  Quite frankly, I can't figure out which combination of terminals are protected by the internal breaker.  I'd fuse or breaker all leads

The manual does say the internal breaker when new would open in 7-8 seconds on a dead A-C short, but aging will increase that duration.   No mention of protection for other post combinations, such as A-B, B-C, etc.  The manual does say that not more than 50 watts should be drawn continuously.  This would equate to 0.67 rather than the 0.75 figure I used.  But it also says to limit continuous amperage to 4-4.5 amps.  If you have much older Lionel equipment, the Greenberg Repair & Operating Manual for Lionel Trains is a worthwhile investment.

Having said all this, in my younger days, back around 1950, I use a Type R (100 watts) to run two locos (#224 & #736), 2 022 switches, and a #97 coal elevator.

@RJR posted:
Quite frankly, I can't figure out which combination of terminals are protected by the internal breaker.

A-B and C-U are not protected by the internal breaker.

@RJR posted:

Rob, Manual says the breaker is 4 amps

Manual says the breaker is set to carry 4 amps continuously, but will hold a slight overload when the transformer is cool.

How to test it though is a different procedure. The manual gives an acceptable time - 9-35 seconds into .2 ohms using A-U.

Last edited by ADCX Rob

I think TVS has been covered really well lately. 1500W 33.3V TVS at Digikey

So while we're on the subject of fuses and breakers, would anyone like to offer some specific product recommendations for panel mount ultra-fast inline manual reset circuit breakers, such as can be achieved with solid state protection devices in the 5 to 10 Amp range suitable for 10 to 20V AC?

Last edited by SteveH
@RJR posted:

Somewhere on the Forum are recent posts by Gunrunner John about push button reset magnetic breakers, reasonably priced.

Thanks, RJR.  A quick internet search of Magnetic breakers on OGR turned up these posted by John:

Sensata-Airpax R11-62-7.50A-B01CV-V 7.5A

Sensata-Airpax R11-2-5.00A-B06CV-V, 5A

Sensata-Airpax R11-2-10.0A-B06CV-V, 10A



https://www.onlinecomponents.c...00aobv-10090622.html

Are these what you're thinking about?

They are definitively less expensive than the PSX-AC and according to that other thread better at lower voltages.

https://ogrforum.com/...afely-run-tmcc-power

Last edited by SteveH

For really fast action, the PSX-AC Circuit Breaker modules are probably the king.  THe Airpax Snapak Magnetic Circuit Breakers are very good, but I can't seem to find the fast acting ones without the hydraulic delay anywhere, those are the model you'd like to have.

Here's the Sensata-Airpax Breaker Datasheet, so tantalizing close, yet seemingly unavailable.  You used to be able to get the instant trip models from Digikey, but now they only stock the slow ones.

Attachments

Steve, I think the push button variety is easier to mount in a panel.  Problem is that if one looks into the catalog where it describes the numbering system, there are a huge number of variations, and no one can stock them all.

Over the years, several forumites have designed various electronic packages for train use, and they or others have packaged component kits which they sold.  I wish someone would do that for an electronic breaker such as is found in the PH-180 transformer, the circuit for which has been posted on the forum.

The -0 models are the instant trip models.

John, Thanks very much for your help.  I just ordered 12 of the -0 (instant trip) for the price of 3 PSX-ACs.

@RJR posted:

Steve, I think the push button variety is easier to mount in a panel.  Problem is that if one looks into the catalog where it describes the numbering system, there are a huge number of variations, and no one can stock them all.

Over the years, several forumites have designed various electronic packages for train use, and they or others have packaged component kits which they sold.  I wish someone would do that for an electronic breaker such as is found in the PH-180 transformer, the circuit for which has been posted on the forum.

RJR according to their site there were 29 (push-button panel mount 10A breakers) in stock before my order, so there should be about 17 left.  Get em while they're hot.

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