Re: Reality Check Needed - See File and/or Read Description
Vollrath, Don <dvollrath@...>
You said “As for isolating the section under the overpass: I was under the impression that a DCC engine operating in a district that experiences a polarity reversal will continue to follow directional cab commands independent of polarity--what then is the advantage of isolating that area?”
You are totally correct in your understanding of train direction control with DCC. The only advantage of isolating a switching yard and powering it through a separate circuit breaker is that this is the area of the layout where operators tend to make mistakes and train cars are most likely to derail and cause short circuits. By isolating power to the tracks and switches in a yard with a separate circuit breaker (CB) district one operator can cause a track short circuit and power to trains on other parts of the layout being used by other operators or simply set up for continuous running will not be interrupted. This is a hot issue on large club layouts. Some folks go overboard. There are arguments either way. But putting in insulated track joiners for sectionalized ‘block or district’ wiring is easy while you are first laying down the track. Cutting in track gaps and re-wiring is more difficult later, when you (may) decide to add CBs. Ditto for breaking the mainline into detection blocks for signaling.
From: WiringForDCC@... [mailto:WiringForDCC@...] On Behalf Of allison.public@...
Sent: Wednesday, February 05, 2014 12:41 PM
Subject: RE: [WiringForDCC] Reality Check Needed - See File and/or Read Description
Thanks, you're very kind about the drawing.
All your recommendations make good sense, and isolating at max train length in either direction from crossover B should work well, as I'm not looking to run anything over 90" max. Leaving the crossover A and the upper portions of B at matching polarity with the loops they connect to will simplify the set-up and lessen the need to worry about two trains conflicting an auto-reverser. Excellent.
Yes, I'm planning to use plenty of drops, and single controls for each of the crossovers, but am glad to hear that advice reinforced.
I will give some thought to the multi-operator scenario, though at the moment it's just me and mine. As for isolating the section under the overpass: I was under the impression that a DCC engine operating in a district that experiences a polarity reversal will continue to follow directional cab commands independent of polarity--what then is the advantage of isolating that area?
I may produce an updated drawing based on your (and Ed's) guidance and put it up to have you confirm I've understood properly, and if so, it may be of future use to anyone else crazy enough to try a layout like mine.
Again, thank you for the explanations & input. VERY helpful.