Further to my previous message, Elliot's original message states that the problem occurs at the switch blade tips. If any sparking occurs here then if the turnout is dead-frog, then it is almost certainly being back fed by a reversed polarity - fed from other end of yard by another controller or a live frog at the other end of the yard ? If sparking occurs and the turnout is live-frog, then it isn't wired properly. See:
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There is also a case to check wheel standards and back-to-backs.
Ok, ok, pedantics - if the poster didn't have an interest in the hobby he wouldn't have a problem!
It wasn't!
then I assume DC is
Why is the short momentary?
This is one of the problems people blame DCC for because it has a
Yeah yeah, we weren't discussing DCC.
stockrail to point touching.
Those are the ones - they are on all HO turnouts that I've looked closely at.
and they certainly don't always misbehave without them.
True, but they are put there for the purpose of maintaining contact when the turnouts get a little dirty, as all turnouts on operating layouts do. You've got about 6 months trouble free operation from new without them.
So how
Yes, but the turnouts only work reliably until the sides of the point blade and stock rail tarnish sufficiently to impede current flow. Put a tiny speck of dust between the two and you get current jumping the tink gap causing sparks.
The turnouts will work without them, but I
Well, from my point of view you've just destroyed one of the best features of Peco turnouts, the automatic current switching.
No!!! If the problem is a miswired live frog turnout then the short will be more than momentary.
Not entirely - the turnout is probably a dead frog turnout and the symptom of sparking is in all likelyhood the cause if it is a dead frog turnout.
Certainly. However, we don't neccessarily have a short. In fact we probably haven't got a short.
however, if the problem is a short, evidently the turnout
Very true, but so far we haven't got a short - you made that up.
- a case for checking wheel standards and back-to-backs.
Agreed, but Peco have covered that point by adding sliding sprung contacts.
All switching should be done
Agreed, but Peco have covered that point by adding sliding sprung contacts, fragile ones admittedly but otherwise reliable over long periods of operation.
And
No - the dead frog and current passing between stock rail and point blade matches the description whereas a direct short does not.
the only way to stop it is
That will NOT fix the problem of damaged point blade contacts, assuming that is the problem. That alteration only provides extra expense and disruption.
The third possibility is that the sparking at the point blade tips is caused by current travelling to the loco motor. That would only occur when the loco was on the track from the point blade on. Live frog Peco turnouts work in the same electrical manner as dead frog turnouts with the exception of the frog wiring. (I think ;-)
Because Elliot described a spark as being observed - which is what happens when a passing short occurs. If it was a long term short (which it wasn't) then the controller would cut out.
Evidently you've only seen code 100 turnouts. None of the code 75 turnouts have them - I know this for a fact because my present layout is full of code 75 in the visible area and has 16 code 100 in the fiddle yard. And Nor do the 009 IIRC. Don't know about code 83. One could argue that all of the 16.5mm gauge turnouts are HO!
the turnouts get a little dirty, as all turnouts on operating layouts do. You've got about 6 months trouble free operation from new without them.
Which is what I said! But as I also said, Peco don't put them on all of their turnouts - have a look at their other ranges.
blade and stock rail tarnish sufficiently to impede current flow.
Which is also what I said!
tiny speck of dust between the two and you get current jumping the tink
gap causing sparks.
Can't say I've ever seen this unless an HF track 'cleaner' is connected.
features of Peco turnouts, the automatic current switching.
Since I mostly use live frogs, I always have switches involved and in my DC days, I always separately fed sidings as isolating sections....which made conversion of the layout to DCC a lot quicker. Relying on turnouts to switch sidings on/off in my view is not good practice. Most layouts I have seen doing this have ended up having electrical problems, especially when live frogs were also in use. Don't forget, even the tabs are not perfect either - I've had several of them fail in the past - that is why I use live frog now (among other reasons).
Greg, do you actually have experience of wiring live frog turnouts ? My layout is full of them, so I know what I'm talking about. If a live frog is not wired properly, it is possible to run out-of-gauge/B2B wheels through the gap between the switch blades and stock rails and get a momentary short, observed by a spark. I have seen this on so many club layouts that I have forgotten how many times I've seen it! I can assure you that as the train passes, it is a momentary short and it certainly isn't enough to trip the cut out on a DC controller. In fact, I have heard people describe it in exactly the same terms as Elliot has done.
symptom of sparking is in all likelyhood the cause if it is a dead frog
turnout.
Sparking is not a cause. It is the result of an electrical fault.
We've either got a short or lost contact. Not sure that we have enough info as yet to confirm one way or the other, but a dead-frog does tend to suggest a lost contact.
Elliot presented a situation which to me and a few others on this list had all the hallmarks of a short. It may be, it may not be. My experience has been that sparking is usually a result of shorting because the voltages and currents we are dealing with are not enough to cause significant sparking unless the track is really dirty. The fact that Elliot described the short as appearing on the tips of switch blades was really a tell-tail. I suppose we do need a confirmation as to whether the spark occurs between the stock rail and switch rail when they are touching or when they are not touching ie being bridged by a wheel.
I think I didn't explain properly. I meant that my personal opinion is that turnouts should not be used as the means of isolating sidings. Sidings should be separately fed using an isolating section so as not to rely on the turnout or its switching. The tabs are really irrelevant
- I don't wire isolating sections because of the relibility of turnouts
- I do it because (especially with live frog) switching turnouts invariably causes shorts due to unexpected circuits being made - I've seen too many clubs fall into that trap. Of course, with DCC, I don't have any of these issues. I simply power every section of track all the time and make sure my turnouts are not back-fed via the use of insulated joints - life is so much easier!
that is the problem.
True - insulated joint won't fix that problem. Probably should use a meter to get an idea of the currents involved.
Really, all of these problems can be resolved by using sound electrical wiring principals and practices in the first place. The trouble is, electrical systems are considered by many as some unnecessary evil and added as an afterthought instead of a properly intergated part of a layout and installed at track laying time. I don't have any of these problems on my layout.
caused by current travelling to the loco motor. That would only occur when the loco was on the track from the point blade on.
True - I intimated to that effect in my last reply.
turnouts with the exception of the frog wiring. (I think ;-)
Out of the box that is true with the exception that they don't all have the tabs (eg code 75 range). However, the out-of-the-box wiring is incorrect and needs to be modified to
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(Peco actually makes code 75's to have these modifications) for them to work properly - in this condition, the switch blades are electrically bonded to the stock rails so there cannot be any 'sparking' between them. A lot of clubs don't modify live frogs and use them as though they were dead frogs and as a result, get themselves into all kinds of trouble with shorts everywhere!
Without going back to the initial post to check the precise original wording, I think "sparking" was described - this could be either shorting or current across a poor connection. As it was a dead frog turnout being described ...
I use both Code 75 and code 100, the Code 100 for the last 30 years.
None of the code 75
You got me there - I guess I just assumed there were contacts on my Code
75s. And Nor do the 009 IIRC.
I only own a couple of those.
Of course they are - Peco 16.5mm gauge track has always been HO. If you Poms want to run incorrectly scaled models on it then that's entirely your own business. ;-)
So far I've only bought Code 75 turnouts when I've needed them, so I haven't studied them on the bench.
If you've got a loco drawing half an amp sitting on the track beyond the points and powered through the point/stockrail connection with dirty contact faces then of course you are going to get sparking - go check your layout!
Why?
which made conversion of the layout to DCC a lot quicker.
Why would you do that?
Why?
Most layouts I have seen doing this have ended up having
Why? The switching of the live frog is separate from the switching of the points.
I haven't had one fail in 30 years - other than from poor ballasting or fingerpoking, for which reason I will no longer buy secondhand Peco turnouts.
Yes, but I have no experience of miswired live frogs. Perhaps I run my locos slower than you but the reason I've moved to live frogs is to get locos across them at scale shunting speeds without stalling. (0-4-0Ts, 2-4-0s etc)
My
True, but neither of us is sure what we are discussing. ;-)
I agree - the bit I'm arguing is your assumption that live frog turnouts are involved when Elliot specifically said he thought the turnouts were dead frog.
I said "... symptom of sparking ..."
I'm interested here for my own purposes! I've been using the isolating feature of Peco turnouts for the last 28 years without problems. Admittedly that's 6 or so layouts and few if any turnouts would have lasted that long.
Why? Using the Peco isolating feature along with other subterfuges has almost allowed me to eliminate isolating switches entirely.
The tabs are really irrelevant
I disagree based on my experiences.
I agree - I have very few electrical problems, and those mostly stem from turnout failure.
I have to admit that my Code 75 turnouts went straight on to the layout as soon as they arrived. I wired them as simple dead frog turnouts but with the frog wired through the on-motor switch from the stock rails. I didn't get them wrong! =8^D
Hmmm, looks like I'm due for problems in the future - I've learned something! I'm a bit puzzled by your "...the out-of-the-box wiring is incorrect and ..." In what sense is it "incorrect"?
I have seen something similar on our club layout. Since I laid the track in question I took some time to investigate. A spark can be generated not only by a short circuit but also by any current interruption. The sparks you see on SR third rail systems are not caused by short circuits but by the breaking and re-establishment of current connections to the traction motors. The same thing can happen in miniature. With A.C. the spark tend to be extinguished over a cycle but with D.C. it can persist. In the days when trams ran in big cities you could hear some quite hairy tales from the power house of what happened when the traction current (D.C.) was interrupted.
Motors can turn into generators as well; that's what regenerative braking is based on. A miniature D.C. motor won't be much of a generator but it also has some inductance.
So the sparking you see is most likely caused by a momentary interruption in the current supply to the locomotive. This can be caused by the dead frog of the point or a combination of track irregularity and loco pick-up geometry. I have noticed that Peco points don't keep the exact same gauge all the way through.
Another factor is the dirt that inevitably builds up on the wheels and track. I noted that, because of the bump in the track going through a point dirt tended to accumulate at that very spot where sparking occurred making the electrical connection even more tenuous.
My partial solution has been to add as many pick-up points to my locos as I can and to keep the track, wheels and pick-ups clean. I have not experienced any pitting of the point blades nor have my Lima Class 73s burst into flames.
I have seen something similar on our club layout. Since I laid the track in question I took some time to investigate. A spark can be generated not only by a short circuit but also by any current interruption. The sparks you see on SR third rail systems are not caused by short circuits but by the breaking and re-establishment of current connections to the traction motors. The same thing can happen in miniature. With A.C. the spark tend to be extinguished over a cycle but with D.C. it can persist. In the days when trams ran in big cities you could hear some quite hairy tales from the power house of what happened when the traction current (D.C.) was interrupted.
Motors can turn into generators as well; that's what regenerative braking is based on. A miniature D.C. motor won't be much of a generator but it also has some inductance.
So the sparking you see is most likely caused by a momentary interruption in the current supply to the locomotive. This can be caused by the dead frog of the point or a combination of track irregularity and loco pick-up geometry. I have noticed that Peco points don't keep the exact same gauge all the way through.
Another factor is the dirt that inevitably builds up on the wheels and track. I noted that, because of the bump in the track going through a point dirt tended to accumulate at that very spot where sparking occurred making the electrical connection even more tenuous.
My partial solution has been to add as many pick-up points to my locos as I can and to keep the track, wheels and pick-ups clean. I have not experienced any pitting of the point blades nor have my Lima Class 73s burst into flames.
Graham has said it precisely. If the under blade contact spring plate is weakened then all current passes via the blade tip. Loco passage and / or stock will inevitably work the bladeand cause small sparks as the blade parts from the fixed rail ( being inductive can be quite noticeable.) Apart from stroking the conductor spring plate back into shape ( as one did with the old type 3000 PO relay blades) there is not much else to do. If the conductor plates are too weakened then it is a case of replacement for the point.
Because if you don't break the links marked in yellow you will have a dead short when you add the links marked in red. Keith
NB. I thought Grahams page would explain it, but the idea is to divide the point up into 3 pieces, left and right stock rail/blade sets and the frog so that the frog polarity can be externally switched. The red links provide power to the blades at the same polarity as the adjacent stock rail so that, 1. you are not reliant on blade contact for power
the blade remains at stock rail potential when open so you can't get shorts through the back of flange contacting the open blade.
His page says _what_ to do, but not _why_. As I'm apparently trying to achieve an end that he has rejected, I need to know why he says each modification should be done.
but the idea is to divide
I can see that that could be a problem for me long term as I hadn't noticed the lack of under-blade contacts.
I've never had that problem so I'm not sure I need to fix it. :-)
I don't want to fix the problem of following track isolation through insulated fishplates because I consider it to be a positive function.
points and powered through the point/stockrail connection with dirty contact faces then of course you are going to get sparking - go check your layout!
This is a problem I just don't have because I don't rely on switch blades as the switching mechanism for exactly the sparking reason.
Because in DC days, if there was a loco already in a siding, it would spring to life when a turnout was changed unless it was separately isolated.
Because in the conversion from DC to DCC I simply connected the isolating section to the main bus and this made the siding live all the time, regardless of the turnout position and because of the insulated joints, the live frogs were already correctly protected against back feeding.
Unreliable switch blade contacts. In DC, everything springs to live in the siding when you change the turnout
The switch is usually attached to the turnout. The point I was making was that I don't believe sidings should spring to life when a turnout is changed otherwise in DC, everything in the siding springs to life. In DCC it just isn't an issue.
fingerpoking, for which reason I will no longer buy secondhand Peco turnouts.
I have.
Hmmm. But in other e-mails you ask the question about breaking the switch rails and connecting the switch blades to the stock rails. You even said you don't break the switch rails. So you do have experience of incorrectly wired live frog turnouts!
frogs is to get locos across them at scale shunting speeds without stalling. (0-4-0Ts, 2-4-0s etc)
Absolutely agree and I do the same.
Yes, but in DC you end up having this constrained operation where you have to keep locos away from each other if you don't have isolating sections and rely on turnouts to isolate them.
I'm a bit puzzled by your "...the out-of-the-box wiring is incorrect and ..."
Because the switch blades are not electrically bonded to the stock rails, the switch rails are not broken and the crossing V is not properly isolated. The reason Peco supply them the way they do is so that they (sort of) function if you use them out of the box. If they were wired properly, they wouldn't work out of the box because they would need an aux switch to handle the crossing V.
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