UCS and constant voltage?

In conventional operation track voltages are usually low in yards or sidings or just to position the operating cars over the UCS.  So you would typically stop the engine, then crank the voltage up to 14V (or so) to properly drive the operating car, then lower the voltage before moving the consist to position the next car, etc..  If you are using the uncoupling function the same 
"extra" step applies as lower slow-speed track voltages may not be enough to fire the uncoupling magnet.

There are two main benefits:
1. ability to use track without having a potential train in neutral- prevents smoke unit overheating and allows for independent use of accessories/ car unloading
2. no reduction in speed/voltage due to higher current draw of the magnet- leads to easier uncoupling "on the fly" and (potentially) stronger "pull" due to higher voltage

Additionally you can use your UCS as a lock-on to supply power the "normal" track rails.

Please tell me more. Does that mean if I run constant voltage to the UCS, it will power the track and, by extension, the entire block? 

That might be ok except I’m using a separate transformer (a KW) for constant voltage to switches, lights, and UCS. I want the track power to come from the other, bigger transformer (ZW). Trying to keep things separate to maximize power to trains. 

Normally the UCS gets it power from the track.  If you connect wire 3 of the controller to an aux power, the ground return goes to the outside rails of the UCS.  If you are using a separate power supply for the UCS, then its common for the aux power  must be tied to the common of your track power (Phasing the transformers together).  Wiring the UCS with an Aux power supply does not make it a lockon to power the track.

@Joe Fermani is correct. However, now that terminal 3 is not connected at the ucs, you can take your variable voltage and back feed it like a lock on to the block as an additional power drop as an often overlooked convince, but it is not necessary to do so.

The following diagram I made for a different thread might help (or not )

This is for an MTH UCS but the idea is the same.  As shown, the 3rd terminal supplies center-rail track power to the controller box.  The lever switch in the controller routes track power to the uncouple or unload mechanisms.

If you instead route the controller's 3rd wire to an Accessory transformer, the UCS unload and uncouple will now operate from Accessory power.  And in breaking the connection to the 3rd terminal of the UCS, that terminal is now "free" to be used as a "lockon" to supply center-rail track power to the UCS track (and any track sections connected to the UCS).  At least this is what I think broman4 meant.

Note Joe's key point that if using an Accessory transformer to power the UCS functions, the two power sources must share a common ground (outer-rail) connection.  Most transformers that have both track power and accessory power outputs make this connection for you.

Joe Fermani posted:

Normally the UCS gets it power from the track.  If you connect wire 3 of the controller to an aux power, the ground return goes to the outside rails of the UCS.  If you are using a separate power supply for the UCS, then its common for the aux power  must be tied to the common of your track power (Phasing the transformers together).  Wiring the UCS with an Aux power supply does not make it a lockon to power the track.

Thanks, that’s what I needed. 

stan2004 posted:

The following diagram I made for a different thread might help (or not )

This is for an MTH UCS but the idea is the same.  As shown, the 3rd terminal supplies center-rail track power to the controller box.  The lever switch in the controller routes track power to the uncouple or unload mechanisms.

If you instead route the controller's 3rd wire to an Accessory transformer, the UCS unload and uncouple will now operate from Accessory power.  And in breaking the connection to the 3rd terminal of the UCS, that terminal is now "free" to be used as a "lockon" to supply center-rail track power to the UCS track (and any track sections connected to the UCS).  At least this is what I think broman4 meant.

Note Joe's key point that if using an Accessory transformer to power the UCS functions, the two power sources must share a common ground (outer-rail) connection.  Most transformers that have both track power and accessory power outputs make this connection for you.

Very helpful, thanks. I currently have the ground terminals linked together between the KW and the ZW. I think that’s what you mean. 

Thank you everyone! Bought a soldering gun to get started with wiring UCS and controllers. Definitely going with constant voltage. At the same time, wiring each siding with blocks and making this panel. Getting into the heart of this layout build.. such fun!

Kevin

Another point worth knowing is that you can power more than one ucs from each controller, which can make wiring a bunch of sidings simpler. This idea has been covered here before.

Rod

Rod Stewart posted:

Another point worth knowing is that you can power more than one ucs from each controller, which can make wiring a bunch of sidings simpler. This idea has been covered here before.

Rod

Thanks, Rod. I did a search and could not find any thread on this. Am I correct to assume that one could just daisy-chain the UCS's and then one controller will operate all of those connected sections at the same time?

You would want to wire them in parallel. Wire the first one up to your controller, then jumper all connection over to the second UCS, etc. I would think no more than 3 per controller would be ok. I have not done this myself but I know I read about it on this forum.

Rod

Rod Stewart posted:

You would want to wire them in parallel. Wire the first one up to your controller, then jumper all connection over to the second UCS, etc. I would think no more than 3 per controller would be ok. I have not done this myself but I know I read about it on this forum.

Rod

This sounded good until I realized that it could uncouple the string of cars in two places sometimes when I didn’t want it to.  Good tip, though!