| ElectroFrog is Peco's
term for a Live (powered) Frog turnout, what some people call power-routing.
With most live-frog turnouts, there are three issues you need to be
aware of in order to use them successfully.
- Wheel flange clearance between the stock rail
and open point
- Frog and frog rail changing polarity
- Point vibration causing power/signal problem
Most so called DCC friendly turnouts
address issue 1. Some point out issue 2 and how to cope with it. Most
do not even mention issue 3.
Most Peco ElectroFrog turnouts can
be used right out of the box with no concern about issues 1) and 3).
Only the occasional special need will require some modification. And
even then, the modification will be easy because of the way Peco ElectroFrog
turnouts are made. Issue #2 is the only issue to be concerned about
with Peco ElectroFrog turnouts (and all live-frog turnouts). Peco InsulFrog
turnouts don't even have that issue to be concerned about. All of these
will be discussed below. |
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With power routing turnouts (except for Peco InsulFrog), both
points usually carry the same polarity. Illustration 1 shows how the
power flows on a normal power routing turnout. Polarity is shown with
Red and Green lines drawn over the rails. |
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| You can see that the
open point has the opposite polarity. If the clearance between the stock
rail and open point is not enough to allow the wheel flange to go through
without touching the point, you will have a short circuit. But you can
see with the Peco turnout above that there is plenty of clearance even
for the fattest wheel flange.
Some manufacturers design their turnouts
with this clearance so close that a short circuit is all but unavoidable
(thus requiring modification to the turnout to make it work properly
with DCC). |
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| Note: These short circuits generally
don't matter when operating with DC analog because the typical power
pack doesn't put out enough current to harm anything (they generally
put out only enough power to run one train). When a short circuit happens,
the power pack simply puts out all the power it can for the short period
of time the short circuit is occurring, and no harm is done. But with
DCC having enough current on the rails to run ALL the trains, a short
circuit can cause harm. Therefore, Short-Circuit Protection is built
into boosters. When a short circuit occurs, the booster shuts down and
the trains stop. |
Some people call this
Power Routing, some call it Live Frog. Illustration 1, above, shows
how a power- routing turnout is powered when closed for the through
route. Illustration 2 shows how it is powered when thrown for the divergent
route. |
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| You
can see that all the track pieces in the middle changed from green to
red. With Peco InsulFrog turnouts, all the track pieces stay the same
regardless of which way the turnout is set.
The reason this is called power routing
is that it can make the route not set for dead. In the illustration
above, you can see that both rails of the through route have the same
polarity. This means a loco can't run (the through route is dead). With
DC analog, people used this to be able to run a loco onto a siding to
let a train pass. But with DCC, this is not needed (simply because each
engineer is controlling their trains independently regardless of track
power). |
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With
DCC, it's more important to have good solid track wiring to all rails.
Running power through the point contacts is not as positive as connecting
the siding directly to the track power bus. So to accommodate a power-routing
turnout with DCC, the frog rails must be isolated from the rails that
join to them, as shown in Illustration 3.
Insuring that the frog rails are isolated from the adjoining rail is
all most people ever have to do to use most Peco ElectroFrog products.
However, some ElectroFrog products require a little additional work,
which will be discussed later in this section. |
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|
With DCC, power
to the points is far more important than power to the frog. The typical
turnout provides power to the points via slip joints, brass contacts,
or some other method. The problem is, when your loco is traversing the
points, the points vibrate. And with just that little bit of movement,
power is interrupted. It's only for just a nano second, but just long
enough to mess with the signals. Unlike a spot of dirt on the rail,
a whole truck of your loco will be on it. This means that 1/2 of your
power pickup for that side is gone for that nano second. At first blush,
this wouldn't seem too much of a problem, and usually isn't - after
all, you still have as much power in the other truck as locos use to
have. But, with so many more things that DCC does than you could do
before, this kind of power interruption can cause spikes that can be
disruptive.
Peco turnout points get power from
two contacts. But more importantly, these contacts are more positive
than on most other turnouts.
- The points make contact with the stock rails like
all others. But, only Peco has a spring that forces the points tightly
to the stock rails. Besides providing good solid electrical contact,
it also resists vibration caused from locos running on it.
- The points also have wipers which make contact
to the bottom of the stock rail. So, with the spring holding the
point tightly against the stock rail, and the wiper making contact
to the bottom of the stock rail, it has two points of contact for
power transfer at that end of the point.
- The points also have a unique pivot connection
to the closure rail. It doesn't just ride on the pivot pad as points
do on some turnouts. It has two tabs that stick through a hole in
the pad, and bend over to secure it to the pad. This provides contact
from the tabs to the hole in the pad, as well as between the top
of the pad and bottom of the point (again, two (not one) point of
contact from that end). Since this is where the frog and frog rails
get their power, it's important that these pivot points have good
contact to provide good solid power to the frog and frog rails
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| It's unlikely
you'll need to modify any Peco ElectroFrog turnout. However, if you
do, it's usually very easy. First, the points are secured to a plastic
throw bar. If you need to isolate the points for whatever reason, all
you have to do is make a cut in each of the closure rails, as shown
in Illustration 4.
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| At that point you'll
have to feed power to the frog rails through an independent switch (like
many other turnouts require). Looking at Illustration 5, you can see
wire connections between the closure rails and frog rails. |
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| All you have to do to
feed power to the frog, frog rails, and closure rails on the frog side
of the cuts is to connect a feeder to the wire spot indicated above.
You can't see it in the photo above, but the tie going down from the
feeder connection is hollowed out to accommodate bringing the feeder
out from under the turnout if desired. |
Some ElectroFrog
products have frogs that need to be powered irrespective to a single
set of turnout points: 3-Way Turnouts, Crossings, Slips, and Crossovers
(Scissor Crossing). Refer to those pages for information about them.
Again, if using Peco InsulFrog turnouts,
none of these issues are of concern. |
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