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:
formatting link
There is
also a case to check wheel standards and back-to-backs.
Graham Plowman
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.
Agreed :-)
Regards,
Greg.P.
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 ;-)
Regards,
Greg.P.
Greg,
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.
Suggest we wait for input from Elliot.
Graham Plowman
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
formatting link
(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!
Regards,
Graham Plowman
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 imagine we've frightened him off!
=8^)
Regards,
Greg.P.
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"?
Regards,
Greg.P.
Now that I've taken a good look at your rewiring diagramme, I have to
ask why you break the links maked in yellow???
(Peco
Where can one get shorts???]
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.
HG from the left hand side of the Atlantic.
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.
HG from the left hand side of the Atlantic.
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.
Peter A
Montarlot
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
2. 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.
Regards,
Greg.P.
Greg,
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.
Graham Plowman
Greg,
Re
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.
Graham Plowman
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