Author Topic: Wiring A Dual DC/DCC Wye  (Read 914 times)

TwinStar

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Wiring A Dual DC/DCC Wye
« on: December 16, 2018, 11:12:25 AM »
My Dallas Union Terminal Module set as most of you know is designed electrically to use both fixed DC and DCC. My use of Dallee dual current detectors allow it to have the signal system, MSS, work in either configuration. The issue now is wiring a wye. I just laid the Kelly lead turnout (this was the name of the mainline turnout that lead to the wye on the north end) and will soon begin laying the rest of the wye and the electrical side of things have become a concern.

The wye is electrically isolated for current detection purposes (the mainlines are detected) and each turnout is Tortoise powered. I thought I had a simple solution but it just moved the reversing section.

I know there are others here more electrically gifted than myself. Thanks in advance.
Jacob Damron
Modeling late 1950's Dallas Union Terminal in Free-mo+ modules

Texas Railway Modeling and Historical Society trmhs.org
trmhs.org

TwinStar

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Re: Wiring A Dual DC/DCC Wye
« Reply #1 on: December 16, 2018, 11:51:40 AM »
The coffee is starting to kick in. Couldn't I isolate the tail section, turnout included, and wire the entire thing off the Tortoise just like the frog? This way with the switch lined properly for either leg the wiring polarity would be correct.
Jacob Damron
Modeling late 1950's Dallas Union Terminal in Free-mo+ modules

Texas Railway Modeling and Historical Society trmhs.org
trmhs.org

Alan

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Re: Wiring A Dual DC/DCC Wye
« Reply #2 on: December 16, 2018, 12:49:10 PM »
Is this the wye?

wye.PNG
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

TwinStar

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Re: Wiring A Dual DC/DCC Wye
« Reply #3 on: December 16, 2018, 12:53:43 PM »
Yes, 'southeast' corner of that pic.
Jacob Damron
Modeling late 1950's Dallas Union Terminal in Free-mo+ modules

Texas Railway Modeling and Historical Society trmhs.org
trmhs.org

Alan

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Re: Wiring A Dual DC/DCC Wye
« Reply #4 on: December 16, 2018, 01:03:19 PM »
Well, depending upon the level of protection you want, you should align the entire wye polarity to the turnout on the main that is thrown reverse. That means preventing one main turnout from being thrown reverse if the other main turnout is already reverse.

Controlling polarity by the wye frog alone means the wye would always be correct for one main turnout and incorrect for the other. An engine entering the wye with the wye turnout thrown against it would cause a short.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

TwinStar

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Re: Wiring A Dual DC/DCC Wye
« Reply #5 on: December 16, 2018, 02:21:46 PM »
Well, depending upon the level of protection you want, you should align the entire wye polarity to the turnout on the main that is thrown reverse. That means preventing one main turnout from being thrown reverse if the other main turnout is already reverse.

Controlling polarity by the wye frog alone means the wye would always be correct for one main turnout and incorrect for the other. An engine entering the wye with the wye turnout thrown against it would cause a short.

I don't think I described things very well. My apologies as I'm still recovering from a redeye turn. I don't recover from those as well as I did when I was younger.

The entirety of the wye is isolated and independent of the main. The prototype, and the model, allowed and allow, respectively, for turning passenger cars and power without fouling the main once clear. Electrically the entire wye, as well as every other non-main track, is gapped or insulated from the mains as not to trip the main line current detectors. The only electrical issue that I see is on the tail of the wye. I was thinking of power routing both rails of the tail in a fashion similar to powering the frog but not through the frog. Circuitron lists the Tortoise as been able to carry 4-5 amps through its builtin DPDT switch. With the tail being 86" I don't think the current draw would exceed the capacity.

I've attached two pics. One a screen shot showing a better look at the wye. The second an illustration literally using kindergarten materials on hand to show the polarity and gaps.

I would normally use either a DC auto reverser or a DCC auto reverser but this module will be using both at different times.
Jacob Damron
Modeling late 1950's Dallas Union Terminal in Free-mo+ modules

Texas Railway Modeling and Historical Society trmhs.org
trmhs.org

Alan

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Re: Wiring A Dual DC/DCC Wye
« Reply #6 on: December 16, 2018, 04:22:40 PM »
I get it now. Yeah, control the tail and wye frog with the Tortoise contacts. Only concern may be sound and light drop out on equipment on the tail when the Tortoise is flipped. The contacts in a Tortoise are break-before-make with quite a wide band gap.
Alan

LK&O Railroad website

When I was a kid... no wait, I still do that. HO, 28x32, double deck, 1969, RailPro

TwinStar

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Re: Wiring A Dual DC/DCC Wye
« Reply #7 on: December 17, 2018, 02:52:20 PM »
I get it now. Yeah, control the tail and wye frog with the Tortoise contacts. Only concern may be sound and light drop out on equipment on the tail when the Tortoise is flipped. The contacts in a Tortoise are break-before-make with quite a wide band gap.

Thanks Alan. I guess that may be the one compromise in a dual DC/DCC compatible module.
Jacob Damron
Modeling late 1950's Dallas Union Terminal in Free-mo+ modules

Texas Railway Modeling and Historical Society trmhs.org
trmhs.org