Airpax Snapac "Instant" Hydraulic-Magnetic Circuit Breaker

I can’t answer your questions, but I will say that those 10A breakers might be too slow.  I got some Airpax Snapak breakers a few years ago.  They were too slow.  Mine are PP11-2, so your PP11-0 breakers may be faster.  I ended up replacing them with Eaton-FAZ-B breakers (3, 4 and 5 amp) and I’m happy with them.

@Lehigh74 posted:

I can’t answer your questions, but I will say that those 10A breakers might be too slow.  I got some Airpax Snapak breakers a few years ago.  They were too slow.  Mine are PP11-2, so your PP11-0 breakers may be faster.  I ended up replacing them with Eaton-FAZ-B breakers (3, 4 and 5 amp) and I’m happy with them.

Thanks for that insight and a good point. The second part of the model number indicates the trip delay.  The -0 is supposed to be "instant".

The time delay plots are on page 65 of the data sheet.

It was offered as a rebuttal to the notion that we need to immerse ourselves in never-ending hand-wringing over trying to make the electric toy train hobby resemble NASA projects.  If electronic components of toy trains are not robust enough in their design or applications, then we need to rethink the design and applications, not fret over multi-dollar protection devices that the manufacturers apparently didn't seem to feel necessary.

As has been explained many times by the electronic experts here, there are only a few things we can do to protect the fragile electronics inside a locomotive, should a fault occur outside the locomotive. The cure to the perceived or real volatility in the electronic components is to source them and design their circuitry so as not to be susceptible to external faults.

My remarks were offered, as are most here, in the spirit of getting a conversation going. They were not made to deride "modern electronics" whatever that means. They were, however, made to try to poke the manufacturers into getting their act together.  My favorite "fix" has been the "add a light bulb and see if that helps" mentality.

@Arthur P. Bloom I want to thank you for your opinion.  You are certainly welcome to manage your model train layout in the way that you'd prefer.  There is no intent on my part here to tell you or anyone else otherwise, and I respect everyone's decisions even if I may not agree.  I'm not trying to tell anyone to over-complicate the way they might desire to wire their layout.  I'm also not trying to convince you or anyone to change their way of thinking about this.  I am trying to learn specifically about how these breakers function.

Rather than continue debating your points of view on this thread, would you please consider starting your own topic to discuss your grievances about your opinions on complexity?

For the sake of any newbies who may be following this thread:

(1) Fuses and circuit breakers are neither new nor novel.  In particular they have not been introduced in recent years as "band aids", and have never been considered such at any time.  They are a fundamental part of electrical safety and have been so since electricity was first harnessed in the 1800's.  This is very, very mature technology and is depended upon every day in thousands of applications, in industry, transportation, offices, homes, and yes even toys. 

(2) Safety does not concern only whether your locomotive or accessory quits.  Your electric train has the capacity to, and very likely has in at least one case in the past, burn(ed) down a house, or at least started a significant fire.  (If it hasn't, or couldn't, why would a safety organization like Underwriter's Laboratories (UL) be so involved with toy train transformers for all of these years?)

My apologies for elevating the discussion.  This is not a political rant.  These are hard-and-fast technical facts.  (This forum has proven to be very helpful in disseminating the important technical facts if you just let it.)

M.H.M.

Well said Steve.

Mike

This is an important discussion as I am always looking for better ways to protect the very  expensive electronics in my trains.   An ounce of prevention versus the pound of cure.  Anytime I see a post on this topic I read and reread making notes that could possibly protect my trains and my layout.

Thanks for bringing this up.

@Arthur P. Bloom posted:

As has been explained many times by the electronic experts here, there are only a few things we can do to protect the fragile electronics inside a locomotive, should a fault occur outside the locomotive. The cure to the perceived or real volatility in the electronic components is to source them and design their circuitry so as not to be susceptible to external faults.

The Lionel PowerHouse 180 has a fast acting (maybe instantaneous?) breaker.  However, none of the postwar transformers have these, nor do many other modern transformers. There have been multiple discussions about this these Sensata/Airpax magnetic and magnetic-hydraulic breakers, as well as similar ones from Carling Technology.  The goal, as I see it, is to add a comparable level of protection to these older transformers. 

While TVS diodes are a good idea, and highly recommended, in the case of a short circuit, the safest and surest way to avoid damage is to remove the electrical current as quickly as possible.  That is the purpose of these circuit breakers.

Why toss/junk a perfectly good transformer, and spend $100+ when a $20 breaker can remedy this?

@rplst8 posted:

... when a $20 breaker can remedy this?

in quantity of 12, these cost me less than $12.50 with ground shipping.  Some other models are closer to $20 individually.

Steve, I had a link for octaport.com but I’ve lost it, ....lots of data on that page........I too found them too slow, but have not tried the -0 TBT,....I’ve tried these in the automotive world for different applications and found the release too slow holding voltage on the consumer as it tripped,....didn’t like that, especially with sensitive components that don’t react well to voltage drops,....hope that helps,..

Pat

@harmonyards Pat, thanks for the tip about Octopart.com.  It looks like a good resource for finding who has what parts.  I'll look at it some more to see if I might be able to find a link to a cut-away for the Airpax.

@SteveH posted:

@harmonyards Pat, thanks for the tip about Octopart.com.  It looks like a good resource for finding who has what parts.  I'll look at it some more to see if I might be able to find a link to a cut-away for the Airpax.

For your notes, on the flip side, we found the reset to be very clean, zero lag, leap years ahead of any thermal breaker,...( normally used in our world) it’s the release we had issues with.....holding voltage on sensitive, and expensive fuel pumps in the performance world.......we were looking for alternatives to ATO’s and fast blows that don’t always react at their “advertised load rating” ........we’ve settled on Eaton breakers and found them a lot faster on the release side, .......I believe another fella mentioned them above as well,....

Pat

I couldn’t find anything in stock at Digikey or Mouser that was instantaneous from Eaton when I looked a few days ago, but this doc below has a cut away of their AR series breakers and they specifically talk about extinguishing grids to control arcing. Is that sort of the feature you were looking for @SteveH?

https://www.eaton.com/content/...eries-ca130003en.pdf

Arthur... I'm not speaking for you OR your wise observations.  However, electronics has grown since the early days of RADIOSHACK. So have the complexity of our trains.

I know there are many, a lot of my friends, that wish to go back to those early days where the most advanced electronic gadget was a door-bell circuit. Once again, those days are over and done.

To advance the hobby, a few of us not all, need to get our heads out of the sand.

@harmonyards posted:

For your notes, on the flip side, we found the reset to be very clean, zero lag, leap years ahead of any thermal breaker,...( normally used in our world) it’s the release we had issues with.....holding voltage on sensitive, and expensive fuel pumps in the performance world.......we were looking for alternatives to ATO’s and fast blows that don’t always react at their “advertised load rating” ........we’ve settled on Eaton breakers and found them a lot faster on the release side, .......I believe another fella mentioned them above as well,....

Pat

Pat, unless I'm misunderstanding your meaning, I think we might be talking apples, oranges, and bananas here on the time delay.  The other mention above was for a slow trip time Airpax with the number 2 in the second part of the model number ( PP11 - 2 - **** ).

There's also the "fast" delay option ( PP11 - 1 - **** ) with a trip curve that sounds like what you could be describing.

If you look closely at the picture in the original post, its a PP11 - 0 - 10.0 - OB -  V which is the instant fruit (I mean delay) . The  - 0 = "instant" PN designation Airpax breaker is supposed to disconnect the load in less than 0.001 second ( 1 millisecond ) if current flow to the load rises above its rating.

Do you think the ones you were using might have been the ( PP11 - 1 - **** ) "fast" that has a curve like this?

@SteveH posted:

Pat, unless I'm misunderstanding your meaning, I think we might be talking apples, oranges, and bananas here on the time delay.  The other mention above was for a slow trip time Airpax with the number 2 in the second part of the model number ( PP11 - 2 - **** ).

There's also the "fast" delay option ( PP11 - 1 - **** ) with a trip curve that sounds like what you could be describing.

If you look closely at the picture in the original post, its a PP11 - 0 - 10.0 - OB -  V which is the instant fruit (I mean delay) . The  - 1 = "instant" PN designation Airpax breaker is supposed to disconnect the load in less than 0.1 second if current flow to the load rises to above about 135% of its rating.

Do you think the ones you were using might have been the "fast" that has a curve like this?

The -1 is the one we tried on a 12-14V circuit, ( 13.90 running ) on a 20 amp service,.... ....I believe you’re correct, we’re probably comparing apples to oranges,....when we forced a trip, and observed the drop out, it was not instant, almost as if the arc was holding load as it moved away from the contacts,.....we bought them since they were cheap, and  I could certainly cut one open if that’s the exercise of the thread,......  

Pat

@harmonyards posted:

The -1 is the one we tried on a 12-14V circuit, ( 13.90 running ) on a 20 amp service,.... ....I believe you’re correct, we’re probably comparing apples to oranges,....when we forced a trip, and observed the drop out, it was not instant, almost as if the arc was holding load as it moved away from the contacts,.....we bought them since they were cheap, and  I could certainly cut one open if that’s the exercise of the thread,......  

Pat

Pat that would be Great!

Having a look inside would certainly answer the main 2 of the 4 questions.

@SteveH posted:

Pat that would be Great!

Having a look inside would certainly answer the main 2 of the 4 questions.

When I go back to work on Monday I’ll grab the one that looks very similar to the one pictured at the top of this thread,...when my customers spend 900-1100 bucks on fuel pumps, they’re very interested in circuit protection ( obviously why) ......we designed an overkill circuit that consists of ATO fuse ( which most of us know can be pathological liars ) , breaker, and inertia breaker ( another Eaton product) for case of collision.....FoMoCo already uses the inertia breaker in circuit so we cheat like heck and borrow their plans,....😉

Pat

Steve I have enough knowledge about electrical to be dangerous and I have not heard arc shoots in twenty years.  I will try to answer your questions about that since you have waded into the area of serious circuit breakers.

A couple of simple observations. No such thing as an instantaneous breaker. The breaker has two pieces of metal and when bad things happen they open.  There is always an arc between the contacts until they are far enough apart. In large heavy duty breakers it takes a serious gap for the arc to stop. Hence the need for shoots. I would guess a minor factor in train applications.

Back  to your original questions go back to Pat and John, speed and the curves on time.

Back feed well we have had cases when motors turned into generators and that wreaked havoc but not a concern with train motors.