Need Fast Acting breakers for Post War transformers

quote:

First of all, a voltage spike does not originate at the site of a short (derailed engine) its the derailed engine that sends increased voltage demand back to the transformer which then sends the spike back out to all your track and it all happens in a nano second.

And a TVS installed inside the engine would intercept that spike.

Or am I missing something?

If your inline breaker can stop the returning spike from reaching the engine, you don't really need one.

Joe

As a circuit breaker only protects from over-current, it will not trip due to a damaging over-voltage spike.

You would need TVS protection to clamp the spikes, for our purposes, of anything over ~ 33 volts. It is possible to get spikes of 100-200 volts or more on a typical O Gauge layout.

As a circuit breaker only protects from over-current, it will not trip due to a damaging over-voltage spike.

I agree.  Same for a fuse. 

And if you check the fuse manufacturers web sites, you'll see "fast-blow" is a misnomer.  Speed of blow depends on percent of overcurrent.

JC642

As you say correctly a voltage spike happens in a nano second. But what you don't say is that no breaker, electronic, magnetic or otherwise, can react rapid enough to control a nano second spike. Overcurrent will trip a breaker, a voltage spike will not. 

Install a TVS folks, inside the engine would be perfect but the average O-gauger is not going to open an engine and work around the fragile components. At the transformer or on down the railpower wire run[s] as near as possible to the track is feasible.

A  jumpered  T- strip for distribution of railpower feeders is good--photo shows 180 watt PoHo power leads connected to a protected strip[white is Common, green Hot].

>>As a circuit breaker only protects from over-current, it will not trip due to a damaging over-voltage spike.<<

Over voltage spikes don't just happen. Over current or over voltage spike are pretty much one and the same and it all originates at the power source. If your fast acting inline breaker placed on the output side trips the returning spike or over current before it reaches the track, why the need for a TVS?

Joe 

Please post the brand and model of a breaker, or fuse, that opens in a nanosecond.

I used nano second more or less as a relative term meaning faster then fast.

That being said, there are lots of really fast inline breakers that will fit the needs of most layouts. I use Lionel locon's. They are faster then internal breakers of the Z4000 and the Lionel 180 bricks and those are fast. They fit my needs.

I'm sure there are other breakers out there much faster if you look, the #91 not even close as being one of them.

Joe 

JC642

We disagree I think you are wrong, you say,"overcurrent and over voltage spike are pretty much one and the same...??". But then I am a good many years obsolete. I will let someone else take up the discussion.

At this point, the thread is going in circles.

Dang CW, going in a circle, isn't that what a majority of us O-gaugers do best?

FOR THOSE OF YOU THAT HAVE ASKED.

Our 5 amp breakers are listed on eBay, item # 360649504830 @ $7.50 each.

On our own website: www.henningstrains.com. Click on the box car at top of page which says "SHOP ON LINE".  Then on LH side click on 'transformers'.  The breakers are listed, pictured and described. There is also a price break for qty.    Harry

This is clearly totally incorrect.  Voltage spikes that damage electronics are in the microsecond or even nanosecond ranges, nothing like an over voltage or over current situation.  Any coil that has a collapsing field can generate a voltage spike, they're not just coming from a power source.

A TVS and a circuit breaker are two totally different components, and they protect against two totally different conditions.

Ok.......one of my "new" #91s arrived in the mail about an hour ago (looks brand new). I alligator clipped it in to my wiring (leaving my marine breakers in series with it) put a consist on the track. Backed the adjusting screw off until the breaker tripped and then added about a full turn. While the consist was running, I put a car on so that the rear truck would short the track. INSTANT trip. Incredible, actually. Tried that several times and each time, it was seemingly instantaneous. The 5 amp marine breakers just sat there. I'll be running more tests on it and report back later, but so far......I'm impressed. If anyone has ideas for other tests for it.....please post them.

Roger

Dewey Trogdon: Caught your pic of the TVS applied to a terminal block,and was wondering where you got the TVS, and what values you used to order the part. I'm looking at a website: www.centralsemi.com and have no idea what part # to order, uni-directional or bi-directional. Is a uni or bi one piece or two. I'm asking this because I've never heard of these devices and it's an embarrasment to me, as an electrician, that I've never heard of these devices for the train world. Although I have to admit that you never can know too much in life. Would love any and all people to add their input as to help out in this situation with info. Thank-You in advance!   

Steam Forever  John   nandwy6b@gmail.com

Here's the TVS you need for Model Train AC Applications. 1.5KE36CA at Digikey

quote:

Backed the adjusting screw off until the breaker tripped and then added about a full turn. While the consist was running, I put a car on so that the rear truck would short the track. INSTANT trip. Incredible, actually. Tried that several times and each time, it was seemingly instantaneous. The 5 amp marine breakers just sat there. I'll be running more tests on it and report back later, but so far......I'm impressed.

Thank you for posting your results.
I hope everybody will keep in mind that the #91 circuit breaker is NOT a substitute for a TVS. It is not designed to protect against spikes. As I posted earlier, if I was running electronic stuff regularly, I would have them set up in conjunction with my #91 breakers. In fact, since I do have a few pieces with electronics, I guess I should get some.

gunrunner john: Thank- You for a quick response, but I'd like to get more specifics if that's o.k. Wiring into( Is it the same as Dewey Trogdon's pic?), uni, or bi-directional. 

Steam Forever    Thank-You  John G.   nandwy6b@gmail.com

I never said they were the same John. What I implied was, on a typical layout there is no need for a TVS if you have good fast circuit protection downstream from the power source. We all know other then internal protection a built in transformer breaker is of no added protection by itself.

Maybe you could enlighten me and post an example of a real situation that could happen on a layout that only a TVS  and not a fast breaker would protect? 

Joe

Roger, I suspect that you had set that breaker for an amp or 2.  Rarely does a modern freight consist pull more than 2 amps.  The test you used, adjusting to the trip point, is meaningless as a basis for comparison. 

GRJ hit the nail squarely on the head:  overcurrent and overvoltage are two different things.  The fuse or breaker protects against the former; a TVS the latter.

How does one tell if a TVD has blown?

RJR,

I respectfully disagree. I was running a Postwar 2343 set pulling a long consist. It was running at around 4.5 amps. The 91 did not trip. Either did my 5 amp thermals. When I shorted the track, the 91 tripped instantly.....the thermals sat there. They and the TVS diodes are the protection I've used for years. I do think that's a good comparison.

Roger

I never said, or even implied, that a circuit breaker wasn't necessary.  In point of fact, I said just the opposite, perhaps you missed this statement?

A TVS and a circuit breaker are two totally different components, and they protect against two totally different conditions.

Yep, right across the track feed, just like he pictured.

quote:

You'll be impressed until the day you forget to re-adjust it down for a lighter load and you lose all protection.

Everything you add or take away from the power load on the track requires a re-adjustment to remain protected. 

That's one of the little secrets of the trade.  

Seriously, there is no easy way in normal operation to see if a TVS has expired.  If they fail shorted, which is the more common failure mode, you'll know for sure!  However, if they fail open, which happens as well, and the short current can also result in cooking it open.  Here's a paper on failure modes of TVS devices.  As they describe in the paper, having the circuit protection before the TVS is preferred, as that will most likely trip when one shorts and the short will remain for easy diagnosis.

Failure Modes and Fusing of TVS Devices - Vishay

gunrunner john: 1 other question; How does one know if the TVS is bad and needs replacing. Is their a way to hook something into the circuit, or check it with a meter, or what do you suggest?  Steam Forever Thank-You  John G.

There is no easy way to test for an open TVS, testing for a shorted one is very easy, it'll be shorted!

If there are any doubts, you can replace them, although they're quite robust and also rarely fail in an open state.

Harry H,

   I like your 5 Amp auto resettable breakers are they slip fit or must they be soldered, also do you have any 7 Amps auto resettables, in your inventory?   I take it they auto reset once the problem is removed, and the power is turned off.

PCRR/Dave

I told you!

CW, what is the basis for this statement, in which you finger me as providing information on the #91.  I provided nothing.  My only mention was to question Roger's method of setting it.  Please revise to finger someone else.

Where are RJR and JC642 getting their information on the #91 breakers?

John, you could check for defective diodes with a scope, but as you say, it's not simple.

All this talk about breaker ´speed´ has me wondering... would these 5A breakers work with a Model Z transformer if I´m only planning on running my PW locos, or would they be too slow?

Thank you,

KenL

quote:

CW, what is the basis for this statement, in which you finger me as providing information on the #91. 

The basis was your statement in which you assumed that since the breaker worked so well, it couldn't possibly have been a valid test

quote:

Roger, I suspect that you had set that breaker for an amp or 2.  Rarely does a modern freight consist pull more than 2 amps.  The test you used, adjusting to the trip point, is meaningless as a basis for comparison. 

It seems that several people have gone out of their way to try to discredit my suggestion to use a postwar #91 circuit breaker as a supplemental, external circuit breaker, not as a replacement for a TVS or anything else.

No, you misunderstood.  Not knowing what amperage they were set for, how can you compare them to a breaker of known rating?  Roger has now explained with more facts.

The bi-polar TVS is kind of a special case.  You need to exceed the trigger voltage for it to conduct, and that's in either polarity.  You could drive it with a signal greater than the trigger voltage and observe the voltage and determine if it was working.  I'd probably use a resistor to avoid beating up the TVS.

Truthfully, even in the aerospace industry, we never came up with a good way to test all the TVS components we used, it was "assumed" that they'd increase the MTBF of the equipment sufficient to attain the desired numbers before they failed.  I think I've seen more failed TVS diodes in the model train world than in the aerospace world.

Guy's, now I'm really lost! I've taken the advice of some of you, pertaining to TVS',and I have to say that it was a valuable learning experience, just to find out about the spiking, in a short circuit situation. At the advice of a forum member, I contacted Digikey.com to place an order for some TVS'. But before I ordered, I asked to speak to a tech and ask some questions. Turns out,with the part number that I gave him, he states that the TVS' that I'm looking to install on the layout are for D.C. power. I told him my voltage range and that we use A.C. power for 3 rail "O"gauge model trains. He told me that I should be using an M.O.V.(metal oxide varistor-I think that's what he called it), to solve the spiking issues for A.C.power. HELP!

Steam Forever  Thanks in advance  John G.

I don't see anything about the PSX-AC Breakers. Did I miss it already? Do they do what they are advertised to do? They are supposed to be lightning fast. Anyone using these?

That tech is wrong.  Both will protect against some transients, but the MOV is much slower reacting, and it also wears out.

John J Giuliano

I was away and responded late to your question. My first response did not make it so here is another:

The supplier of my TVS was Mouser Electronics 1-800-346-6873

                            or

Mouser Electronics, Clayton Carter,1000 N.Main St. Mansfield ,Texas 76063

Ph. 1-817-804-3800

The Mouser part number: 576-1.5KE36CA. Cost about $.40 each for 100 units.

They are bi-directional and are wired directly across-the-line like a short.

 Photo: 3 as shipped.