I've plunged for 10 amp W28s for the museum layout. They pop fast enough to suit me under a dead short at 1/4 throttle on the ZW, and there's plenty of margin for running anything up to and including a twin Pullmor GG1... 
Mitch
Here is the AirPax Instant trip times:
Here is the W28 series trip times (I've colored the area where the best of the W28s fall behind the protections of the Instant AirPax above):
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SteveH, bmoran4, GRJ, everyone—
Thanks so much for your kind replies/ thoughts/ advice on picking either the 7.5 or 10 amp rating of the Airpax breakers for my ZW. Right now my layout has totally separate double-track mainline loops. Per loop, I am running only a single engine of various types (Legacy diesels, and steam) with occasional running of 5- 1950’s Santa Fe aluminum passenger cars with TMCC Santa Fe A-A units with a total of 2 motors. Wire feeds to each loop are 14 gauge wire. I also want to be able to run 2 separate trains/ engines on one of the double track loops. Layout is approx 30’ long x 12’ wide.
So I will go with the (4) breakers of 10 amp ratings for each of the 4 outputs of the ZW.
Again, thanks for your help.
Carl J
Wondering if these Airpax 5 amp pp-11-0-5.00A-OA-S breakers are ok to use. I understand the '0' indicates instant, and the 5 amp rating....past that I am not sure if these are suitable for our applications. Thanks in advance, Jeff
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Well, they will limit you to a 5A maximum current on the tracks. If that isn't an issue, they'll work great. 
Thanks John!
@jeffrey O'Brien 082418 Yes those look fine and should operate like the PP11-0-5.00A-OB-V. The difference is the ones you're asking about come with Faston to screw terminals adapters. Where did you find them?
Steve, I found them on ebay. Seller had 4 of them, paid just over $30.00 for all 4 shipped. I thought that I would give the 5 amp a try given the price, then I noticed that the product numbers were not quite the same as in the pictures of the ones you have posted. Thank you for clearing up my concern; and thanks for all the research you have shared with forum members regarding the Airpax breakers.
For anyone wanting the Airpax 7.5A Instant breakers, they appear to be back in stock at Online Components
@jeffrey O'Brien 082418 Thank you for passing along your source for the 5A screw terminal variety.
@SteveH posted:For anyone wanting the Airpax 7.5A Instant breakers, they appear to be back in stock at Online Components
@jeffrey O'Brien 082418 Thank you for passing along your source for the 5A screw terminal variety.
I got some of mine from them and some of them from Sager Electronics.
John
Steve, thanks so much for this wonderful thread. I read it through several times with a good sleep in between to make sure I understood your input. I have ordered the breakers from the sources you listed. I ordered 2 each of 10, 7.5 and 5 amp. Half are back ordered till later this spring, but at least I have a plan. I am just now getting back into trains. When I last ran trains (in the 1970’s) it was O gauge tubular 3 track Lionel’s from the 50s. While my brother now has that set, I have been buying various old stock and accessories from that era. I now have about 100 ft of track and most of the other stuff I need and purchased a refurbished Lionel ZW (R) 275 amp transformer.
Again, it is my intent to run only the old stock, only on the old track. Engines, a few lighted cars and some decouplers, lighted buildings and street lights. I intend to have inner and outer tracks, switches, and a number of sidings. Overall size is about 8ft x 12 ft with several levels (mountain), etc. I was particularly excited to see your thread about running the 4 “terminals” independently and having breakers on each… new idea that was very helpful.
So, with that in mind, here are my questions (and please… excuse the ignorance… any experience I had as a kid was rudimentary and my one electrical engineering class was 35+ years ago). First, I have no clue what that diode is all about. What it does or how it works. Your helpful diagram shows the line coming out of the terminal (and thru the breaker), connecting to the middle track and coming back via the outer track to the common closing the circuit. But tangential to that and not in line with it the diode is just connected across the two lines. What does that do and how does that help. Additionally, there is another one just hanging out on the other side of the track. It is all perplexing… again, excuse my ignorance on the topic.
Secondly, my layout as a kid was an outer and inner loop. One power connection near the transformer and of course loss of power on the other side (and now I know why). But when I added an additional small loop off the side (and put power on it), as the train crossed over into that area the train would immediately reverse direction. I went off to college soon there after and never “solved the issue”. Off to army and life so… here I am building a new one and need to ensure I can hook up my power at multiple points on multiple loops and sidings that I can turn on and off. I’m sure it was a simple fix but… a little help as I begin laying this out to wire would be great.
Final question (for now), I have a number of those Lionel connections and was intending to use them to connect my power by “clamping” them to the track. But I have seen a number of people talking about soldering wires for a more positive connection. Had never seen that done. I have both the skill and equipment to do so… is that how you all suggest I connect power? Thanks again. Wonderful thread!
@Chills posted:...I have a number of those Lionel connections and was intending to use them to connect my power by “clamping” them to the track. But I have seen a number of people talking about soldering wires for a more positive connection. Had never seen that done. I have both the skill and equipment to do so… is that how you all suggest I connect power? Thanks again. Wonderful thread!
Let me say that just about everything you said count me in.
Re the above, the other complicating thing for the CTC lock ons is if you buy new tubular track from Menards, they will not fit without adjusting to the clamping posts, and even then they will sometimes disconnect if you bump them. I've spent a lot of time trying to see why things aren't running only to find out that the lockon is off.
Based on the OPs recommendation I bought 2 'PP11-0-10.0A-OB-V ' from onlinecomponents.com, and they should arrive today.
Sorry, another question already… I won’t have the first of the airpax breakers in till next week so haven’t held them in my hand. How do you all connect them? Is it just a spade style connector?
@Chills posted:Sorry, another question already… I won’t have the first of the airpax breakers in till next week so haven’t held them in my hand. How do you all connect them? Is it just a spade style connector?
It depends on the configuration of the breaker. I know of at least two variations. One has screw terminals, and another has tabs. I believe the tabs can accept TE FASTON connectors, or a soldered connection.
Answers follow:
@Chills posted:Steve, thanks so much for this wonderful thread. I read it through several times with a good sleep in between to make sure I understood your input. I have ordered the breakers from the sources you listed. I ordered 2 each of 10, 7.5 and 5 amp. Half are back ordered till later this spring, but at least I have a plan. I am just now getting back into trains. When I last ran trains (in the 1970’s) it was O gauge tubular 3 track Lionel’s from the 50s. While my brother now has that set, I have been buying various old stock and accessories from that era. I now have about 100 ft of track and most of the other stuff I need and purchased a refurbished Lionel ZW (R) 275 amp transformer.
Thank you for the kind words and I'm glad you found this thread to be helpful. If you would like to order the out of stock breakers, there are other distributors besides Online Compnoents. Domestically, Octopart.com is a good resource for showing which distributors sell various electronic components. Just type in the exact make and model number of the part you're trying to find.
I think you mean a 275 Watt ZW transformer.
@Chills posted:First, I have no clue what that diode is all about. What it does or how it works. Your helpful diagram shows the line coming out of the terminal (and thru the breaker), connecting to the middle track and coming back via the outer track to the common closing the circuit. But tangential to that and not in line with it the diode is just connected across the two lines. What does that do and how does that help. Additionally, there is another one just hanging out on the other side of the track. It is all perplexing… again, excuse my ignorance on the topic.
TVS diodes (link here) clamp high voltage spikes which is why they connect in parallel with the Hot and Common. The way they work is they become conductive only when the voltage across them exceeds their threshold. Derailments lead to rapidly changing voltage differences on the track circuit which causes electric coils (found around the layout in motors, transformers, solenoids, relays, and electromagnets) to force current to continue flowing as the voltage fluctuates rapidly due to the bouncing of train wheels, especially at switches. These voltage spikes are well above the component ratings on sensitive electronics found in newer command control locomotives and occur at a very high frequencies. The reasons for multiple TVS diodes around the layout is that even though the TVS diodes clamp the voltage to a safe level in one place, just inches away the high frequency voltage can be approaching a hundred volts. Unless, you're using MTH's DCS control, more distributed diodes are best (however if using DCS, the capacitance of multiple TVS diodes can degrade the DCS signal). My example showing only two was just to show how they connect. As far as where to connect them, the closer they are located to the sensitive electronics they're intended to protect, the better. I like to actually install them in more expensive locomotives right at the Control Circuit boards' power inputs from the track. Other good places are near transformers, any other coils and switches on the layout.
@Chills posted:Secondly, my layout as a kid was an outer and inner loop. One power connection near the transformer and of course loss of power on the other side (and now I know why). But when I added an additional small loop off the side (and put power on it), as the train crossed over into that area the train would immediately reverse direction. I went off to college soon there after and never “solved the issue”. Off to army and life so… here I am building a new one and need to ensure I can hook up my power at multiple points on multiple loops and sidings that I can turn on and off. I’m sure it was a simple fix but… a little help as I begin laying this out to wire would be great.
This sounds like it may have been a brief power interruption caused by a short unpowered or insulated section of track (maybe in the switch). These can be easily diagnosed with a multi-meter to find out where power is being interrupted.
@Chills posted:Final question (for now), I have a number of those Lionel connections and was intending to use them to connect my power by “clamping” them to the track. But I have seen a number of people talking about soldering wires for a more positive connection. Had never seen that done. I have both the skill and equipment to do so… is that how you all suggest I connect power? Thanks again. Wonderful thread!
Soldering is a great way to make secure track connections. Which method you choose is a matter of personal preference.
@Chills posted:Sorry, another question already… I won’t have the first of the airpax breakers in till next week so haven’t held them in my hand. How do you all connect them? Is it just a spade style connector?
The models of breakers provided in the original Topic Post at the beginning of this thread all have "spade" connectors. The female connector that attaches to them is a 0.25" Faston connector.
I was about to fire up my track with my brand new CAB-1L and BASE-1L, with my ZW with tvs diodes connected across the pairs of the 4 posts, and connecting my ppii-0-10.0a-ob-v circuit breaker. This would be to run my brand new TMCC capable 18565 loco. I remembered this thread, so I went back to look at your diagram. I didn't notice the first time that you have 2 diodes connected. I'm guessing that's not a mistake, but is it necessary? Then again, I don't want to fry my new stuff.
The closer the TVS diode is to the engine the better it works. Ideally it should be installed in the engine. Short of that, putting them on the tracks in multiple locations is a close second.
John
@texgeekboy Please see the second part of my post just before yours to see an explanation of where TVS diodes should go to provide optimum protection of the electronics in locomotives. To answer your question, extra TVS diodes are not necessary but are good insurance.
Sorry, late in replying... busy week or so. back to the TVS diodes. so if I connect them along various places on the track (I'll be running about 70 ft in total), I am (for example) using a snap link and then wiring this up between the two connections? sorry, again this type of protection is new to me. secondly, it is "absorbing" the extra voltage to reduce it? does it burn up (ie I have to replace it after each event) or somehow dissipate the voltage after? this may work even if the breaker doesn't blow? thanks for tolerating the many questions. I appreciate all the help this thread and the members have provided.
A circuit breaker protects against current overloads. It goes in line with one of the power leads to the track. You only need one.
A TVS diode protects against voltage overloads. It goes across the power leads to the track. Several, spaced around the layout are recommended.
Mike
