Wiring Insulating Multiple Loops?

Yes.

The U or outside rails are connected internally in the ZW, so they can be connected on the layout. A-U loop 1, D-U loop 2.

This is only necessary to create separate power districts when running conventionally. Then, one controls separate trains with different throttles of the ZW.

When you move to DCS, that is when you create "blocks" within a power district by isolating sections from another. This can be for voltage control, but is primarily done to maintain a good DCS signal. Also, you may only need one transformer or power district. Two won't be a problem.

The caution is that when crossing between the two during conventional operation, one should keep the voltages the same to prevent damaging your trains with over voltage. This is called bridging transformers. When the voltages differ, the result is the sum of both outputs. Not a concern with command operation as both are set the same.

A unintended by- product of placing the two diverging tracks together of a pair of switches is that the outside rails (loops) may be isolated if they are pre-wired for non-derail operation. This is not a bad thing.

I would recommend that you wire the layout now for DCS. It won't inhibit conventional operation. Then you just add-in the TIU and run DCS command.

The DCS Companion will get you through this. Well worth it, especially if you are heading to DCS. 

Moonman posted:

Thanks for the detailed reply, Carl!

Moonman posted:

The caution is that when crossing between the two during conventional operation, one should keep the voltages the same to prevent damaging your trains with over voltage. This is called bridging transformers. When the voltages differ, the result is the sum of both outputs...

The voltage is not added, or summed, the voltage is the difference between the two blocks. The problem is actually the current, especially with using a ZW as you have.

With a 6-7 volt difference when bridging from A-U to D-U for example, there is a 20+ amp fault current that is forced to flow through the hardware making the bridge,  your wiring powering the two blocks, and between the secondary windings of the ZW.

You can get away with this for decades running just postwar trains and enough resistance in layout wiring, but the voltage spikes resulting from the collapse of the current surge have a cumulative & sometime immediate damaging effect on semiconductor electronics.

Thanks, Rob. I think I'll just advance with the DCS plan and skip trying to run two conventional trains.

ADCX Rob posted:

Moonman posted:

The caution is that when crossing between the two during conventional operation, one should keep the voltages the same to prevent damaging your trains with over voltage. This is called bridging transformers. When the voltages differ, the result is the sum of both outputs...

The voltage is not added, or summed, the voltage is the difference between the two blocks. The problem is actually the current, especially with using a ZW as you have.

With a 6-7 volt difference when bridging from A-U to D-U for example, there is a 20+ amp fault current that is forced to flow through the hardware making the bridge,  your wiring powering the two blocks, and between the secondary windings of the ZW.

You can get away with this for decades running just postwar trains and enough resistance in layout wiring, but the voltage spikes resulting from the collapse of the current surge have a cumulative & sometime immediate damaging effect on semiconductor electronics.

Rob,

Thanks for correcting the electrical details.

JCRail posted:

Thanks, Rob. I think I'll just advance with the DCS plan and skip trying to run two conventional trains.

JCRails,

No, don't skip running trains that you have in conventional mode. The problem goes away when you change to command operation and all power districts are set to the same fixed voltage.

The cross-over move just requires some forethought and caution, just as it does with a real railroad. Switching always deserves caution.