How quick trip does a breaker need to be to protect PS-2 or 3 in conventional?

Faster than light! 

I would think the faster, the better here? I might be overlooking something. Maybe "the guys" will answer soon.

It is more important to have voltage spike protection via TVS diodes to protect modern electronics in a conventional environment rather than  over current protection protection.

Everything you wanted to know (and more) about TVS diodes:

https://ogrforum.ogaugerr.com/...uts-thoughts-on-this

TVS Diodes and Circuit Breakers should be used in conjunction with each other to cover over current and over voltage situations.

"How fast should the break occur?"

How fast does it take to weld something to the rail? Faster than that...

Well yes & no.  I have a very fast PH180.  I also have 2 switches, not readily reachable of course, where some cars do a quick short as they pass through.  Breaker opens immediately. Almost impossible for these old bones to reach and no obvious reason fr the quick short.

Lionel #91 postwar adjustable MAGNETIC breakers are likely the fastest for conventional. Any break in the flow pops the connection mechanically.

Dial it in startiñg low, and adjusting until it stops popping.

CW Burfle used to always swear by their reliability in conventional (rip) 

https://www.tandem-associates....el_trains_91_acc.htm

(I think the #91 prewar metal signal box type may be thermal. Also thermal is the #92 "normally closed" direction button/breaker (looks like a hefty, less rounded #90. Likely only good for 25w though)

TVS add on is for boards and is more akin to a filtering of something that might occur once in a blue moon, than a necessity..low price insurance.  A good high voltage static shock from carpet can wipe a board sometimes. During derails shorting/sparking/fields moving/etc. can create a micro-second of anything lol... a tvs should grab and eat any hi- volt shock danger a breaker doesn't care about. An external breaker /fuse is still a good idea to protect wiring from the power supply amperage.

When you fuse or breaker you have to ask "what and where is being protected.

If your trains never use more than 3a constant , your ideal breaker point is 3a.

Also in play are peak amps present in motor starting or under heavy load changes, so you actually likely pull a bit more amps than any random readings you take, unless you have a good meter with max. reading recall/peak hold.

To protect wiring you fuse/breaker below it's max rating. That may or may not be the same fuse rating above depending on strength or weakness in wiring gauge choice in relation to the power available.

I.e.  How many amps? You tell us.

Adriatic posted:

(I think the #91 prewar metal signal box type may be thermal. Also thermal is the #92 "normally closed" direction button/breaker (looks like a hefty, less rounded #90. Likely only good for 25w though)

Actually, the pre-war $91 is a magnetic breaker, and very fast.  I actually use one on my test bench when I'm powering up something that may attempt to draw excessive current as it's quick to react.  I also have a 2A thermal breaker on the bench test supply, and the #91 beats it every time if there's a short.

Tom Tee posted:

How quick trip does a breaker need to be to protect PS-2 or 3 in conventional?

 If you mean to protect the electronics in the trains from transient voltage damage, a breaker should trip just before the damaging voltage spike occurs.

That's impossible, so I would recommend Transient Voltage Suppression instead.

The breaker should be sized for the intended load, and the capacities of the electrical circuit & transformer for overload protection.

ADCX Rob posted:

Tom Tee posted:

How quick trip does a breaker need to be to protect PS-2 or 3 in conventional?

 If you mean to protect the electronics in the trains from transient voltage damage, a breaker should trip just before the damaging voltage spike occurs.

That's impossible, so I would recommend Transient Voltage Suppression instead.

The breaker should be sized for the intended load, and the capacities of the electrical circuit & transformer for overload protection.

Transient voltage spikes do not always occur under situations that would also trip a circuit breaker. It would be foolish to solely rely on even the fastest circuit breaker. As such you need to protect with both circuit breakers and TVS diodes.

As others have suggested, the TVS is more important for protecting the electronics.  They kill the spikes that are dangerous the electronics that post-war engines don't care about.  As for breakers, they are there to protect your transformers and layout wiring mor than anything.  They also can save the day if you get a derailment that would damage the wiring in an engine or, more often, a lighted car.  

As for sizing a breaker there are pretty much two routes you could take, and the choice has more to do with your preference than anything. I prefer the second option here which is more common.  

First, you could choose the current rating based off of the highest load you expect to have.  For example if you know you'll never draw more than 4 amps unless there is a problem, you choose a 4 amp breaker.  This option is just a bit less likely to have you damaging anything, but limits what you can run if, say, you pick up some new/old engines/cars that draw more current.  

Option 2 is to choose the breaker based on the maximum current that your layout can safely supply.  Assuming you used suitably gauged wire, this is most often about 10 amps, as that is the limid per channel on most modern transformers.  This approach will let the breaker do it's primary job, protecting the track, wire, and transformers, but may not protect the smaller wire in an engine or lighted car if for example you derail and have the center rail pickup on one truck land on the outer rail.  

In either case it's worth mentioning that most breakers have a response curve, meaning that the speed they trip varies depending on how much they are over loaded.  if you want them to trip near instantly at 10 amps, you probably want to use a 7 amp breaker, which may allow 8 amps to flow for some time.  

When it comes to types, any cheap modern breaker is good enough to do its job.  If you want something faster, the old magnetic breakers seem a popular choice, but for something new you need something like the PH180 or similar device that actively monitors the current.  Honestly I don't see much point in the extra cost in electronic breakers.  They are great when they are pretty much free as is the case with the PH180, but I don't see enough benefit in them to pay over $50 each.   If I were that concerned about protecting the engines I think I'd opt for putting a TVS and a couple amp fuse inside each engine for a couple pennies.  

I agree the TVS and perhaps a 2A PTC in each locomotive would be great protection, but who wants to open 150 engines to install them?

gunrunnerjohn posted:

I agree the TVS and perhaps a 2A PTC in each locomotive would be great protection, but who wants to open 150 engines to install them?

If I thought it mattered enough to spend hundreds of dollars on circuit breakers like some folks do, it seems like a better use of time and money.  I'd probably do the job when I acquired each new item and wouldn't mind the 15 minutes it took for each one.  it's also the sort of thing I'm surprised the manufacturers haven't bothered to do from the factory when it is common place in most all consumer electronics.  

Of course that's the sort of job I imagine someone else doing.  For my self, I only have a dozen engines and know how to make my own electronic breakers for a couple bucks per channel.  Also have never actually had the electronics fail in any engine I've owned, running them off a ZW with no added protection, maybe after one dies on me I'll be more concerned.  

Folks just keep in mind the simple fact that a Circuit Breaker only protects the transformer and and its wire runs from current overruns and surges.

The TVS is necessary to protect the electronic equipment as well as the locomotive's fragile wires and solder traces from voltage spikes. As our EE friend Dale Manquen (RIP) several times reminded us, a voltage spike won't trip a transformer's current-responsive breaker and protect your electronics.

TVS are cheap--buy a bunch.

As in my opening question, my concern IS the electronics.  So more on the TVS please.  Source, cost,  exactly where to mount?  Between   the Z-1000 and the terminal  board like the circuit breaker?

Will it also be applicable for DC?

bmoran4 posted:

It is more important to have voltage spike protection via TVS diodes to protect modern electronics in a conventional environment rather than  over current protection protection.

Everything you wanted to know (and more) about TVS diodes:

https://ogrforum.ogaugerr.com/...uts-thoughts-on-this

TVS Diodes and Circuit Breakers should be used in conjunction with each other to cover over current and over voltage situations.

Tom, click on bmoran4’s link above, and the thread will give you all the info you need including product specs, etc.  If you have further questions, of course ask.