Powering sidings- Part 2 for tubular track?

@patternpilot posted:

I used my AIU to control the sidings. Since the AIU cannot handle the current needed to power track I installed relays to switch on track power to the sidings. I then installed watchdog signal generators for all the track. When the siding is turned on the engines sees the signal and will start up when commanded. This all allows me to control power to the sidings from my remote.

Ummm; the relays in an AIU are all rated at 10A 250V. How is that not enough to power track all by itself? Or did I miss something?

And look at the size of those traces!

Rod

The AIU underwent several revisions, some of them have 5A relays.  We had a big discussion about this several years back.

hokie71; It's worth mentioning that my operation is all DCS, TMCC, Legacy. So in this scenario the siding UCS's are useless as all yard car placement is done with an, umm, uh, switcher(?). In a non-command scenario they would likely be very handy, and of course in 1998 I was all conventional operation. If there is ever a need or reason to tear up track in my yards, the USC's will be gone for sure. The ones out in the switching/make up area will remain because they get used quite a bit, and there are several dump cars that the grandkids like to operate in that area also. Well, ok, so do I.

Rod

@gunrunnerjohn posted:

The AIU underwent several revisions, some of them have 5A relays.  We had a big discussion about this several years back.

Probably patternpilot is referring to the 5 amp version. Still I would have no issue using them for powering sidings, yard tracks etc. Was the 10 amp version earlier or later? My AIU's were bought in 2016, so likely 2014-15 production.

Rod

I suspect the 5A was earlier, and the AIU spec says 4 amps I believe.  Here's a shot of one of mine from 2015, so it's obviously older than that as I bought it used.

OK, some are quoting my post asking where I was coming from with the relay use. It has been a couple of years but there was a thread on here regarding using the AIU ACC ports to power sidings and yard tracks. At the time someone pointed out that ACC ports could not handle the amperage the tracks may draw so they should be turned on using relays. I was very new to command control so while I was only a reading participant to the thread I took what was said as gospel and went with it. I tried to find the thread but no joy. It may hay been because the ACC ports are only momentary and non latching. All of my sw ports are used. Correct me if that is incorrect.   

@patternpilot posted:

...

It may hay been because the ACC ports are only momentary and non latching. All of my sw ports are used. Correct me if that is incorrect.   

The AIU ACC ports can be either momentary OR latching.  For momentary action an AIU ACC relay is triggered only for as long as you press and hold down the "ACT" button on the DCS remote.  For latching action, the AIU relay is triggered when you press the "ON" button...and stays triggered until you press the "OFF" button.

The AIU SW ports are only momentary and non-latching.  There are two relays inside the AIU for each SW port.  One relay fires for exactly 1/2 second when you press the "DIVERGE" button on the remote.  The other relay fires for exactly 1/2 second when you press the "STRAIGHT" button.  There have been OGR threads on how to add an external latching relay to an SW port so that the SW port becomes latching...for example to drive a Tortoise or similar "slow speed" switch machine that requires continuous power.  And if you run out of AIU ACC ports...but have a few unused SW ports, the same method of an external latching relay could be used to effect ACC port functionality ... albeit you activate the external relay ON and OFF using the "DIVERGE" and "STRAIGHT" buttons which may be awkward!  Or just buy another AIU and get 10 additional genuine ACC ports since a TIU can support 5 AIUs.

All my sidings are automatically powered on using a Triac relay that is controlled by the position of the turnout to that siding. That eliminates the need for additional controls and also prevents an engine on the siding from joining the main track if the turnout is in the "wrong" position.

@Bruce Brown posted:

All my sidings are automatically powered on using a Triac relay that is controlled by the position of the turnout to that siding. That eliminates the need for additional controls and also prevents an engine on the siding from joining the main track if the turnout is in the "wrong" position.

So throwing the turnout to the siding turns power on to the siding as well? That seems like a nifty idea and quite foolproof too. Can you provide any details for the "Triac relay" please?

Rod

Rod,

Here is a schematic of the Triac schematic I've used for all my sidings. It's important to use it with a thermal circuit breaker in series with the "hot" (non-common) output of your transformer or TIU for protection of the Triac. (It's always good practice to use a circuit breaker for protection of all your electronics.) Note that you need to use switch contacts that are built into many turnout switch motors. You can also do siding block control with a SPDT mechanical relay but that typically requires a separate fixed power source to energize the relay. I can also provide you a schematic of that approach. The advantage of the solid state approach is that no separate power source is needed but the minor disadvantage is that you get a voltage drop/loss of about 1 volt AC (i.e., an output of 18 VAC from the transformer results in about 17 VAC delivered to the track.) This has never caused a problem on the sidings using conventional, DCS or Legacy/TMCC operation.)

For people using the DZ series switch machines, a DZ-1008 Relay Module can simply be used to apply power to the siding making things very easy!

Bruce