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A couple months ago I posted my thoughts on the electrical circuit needed to get safe power from the transformer to the tracks.  After some great input by Dale H, HOSO&NZ, and Dale M, this was the finished diagram:

 

PH180 – TIU (Rev L) – terminal block – TVS 30V 1500W – track – car/engine rollers – 22uh 0.5 amp choke – TMCC board/other DCS signal killers

 

Shortly after this, I read about the passive TIU mode where track power did not go through the TIU.  This interested me because I have a fairly long mainline in my new track plan where I can run multiple long passenger trains.  I now think a TPC400 with 20 amps would meet my needs better than the 10 amp limit on the TIU, and I understand the arc welding concern expressed by some when using the TPC with two PH180s.  I don’t need the TPC for conventional control, I’m just using it for the higher amps.  My new power circuit looks like this:

 

TPC400 (powered by two PH180) – terminal block – TVS 36V 1500W – track – car/engine rollers – 22uh 0.5 amp choke – TMCC board/other DCS signal killers.  The TIU (Rev L) would be connected between the TPC and the terminal block (with the TIU red post connected to the TPC post A, black to U).

 

My questions are 1) what wire size should I use and 2) will the 36V TVS be adequate for this new circuit?  Any other comments would also be appreciated.

 

Thanks.

Ron

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Why did you move from a 30V TVS to a 36V TVS?  The output voltage from the bricks remains the same.

 

I don't get the reasoning behind needing a TPC to connect 2 bricks to the track.  With a TPC, the two transformers are connected directly together at the input to the TPC, and the only protection that the TPC provides is a 20 amp thermal breaker that you can buy for a few dollars.  What is the TPC adding to the equation if you aren't running Conventional?  Remote On/Off?

 

The wiring inside a TPC is:

Transformer Neutral/Common tied directly to U at the terminal strip

Tranformer Hot to circuit breaker

Circuit breaker to Triac

Triac to A

Dale,

 

I will keep the 30V TVS in the circuit.  Thanks.

 

Also, while I run command nearly all the time, I do want to maintain the capability to run conventional when friends drop by. I cannot use the TIU for conventional when it is wired in passive mode, so the TPCs will provide that.

 

That said I did not now I could just wire two PH180 bricks directly to the same track terminal posts and get 20 amps total to the track. Obviously my electrical knowledge is somewhat lacking, but would not the 10 amp CBs in the PHs trip when more than 10 amps starts going to the track?  Assuming I can find appropriate CB protection it sounds like if I want more than 20 amps, I can just add a third PH.  Boy, I wonder how many powered engines I could do in a lash-up if I had 30 amps

 

Ron

I run command only but find being able to turn track power on/off from the remote - or by computer - extremely handy.  Plus shutting track power off with the emergency stop button on the CAB-2 or DCS handheld.

 

That said, I am a little unclear about the statements that a TPC isn't useful for paralleling two bricks.  On some other threads there are dire warnings not to do so WITHOUT a TPC, since the two bricks may not output exactly the same voltage.

 

See, e.g., https://ogrforum.com/d...ent/9173459952817787

 

Is this not really a problem?

Last edited by Professor Chaos

I am wondering if anyone has ever measured the current capability of the track they are using? I mean, in todays environment of 20 plus amps available to the rails just how much current can the track handle before it starts to heat up. You have people putting trains with 4 or 5 engines all motored and a string of passenger cars on the track and the train may be drawing between 15 and 20 amps just running. All that current is traveling down a single center rail which, if the layout has super O track, may be a rather small strip of brass, not copper. Other track has more substancial rails but again they are made of tin or what have you but not copper. Then add the resistance caused by a balckening agent and you may have a case for track heating. I admit not a common occurance but some that run high current draw trains may have a reason to be cautious.

 

Al

I had been cautioned that my hook up was potentially dangerous. I was running a 180 brick to the TIU and then an additional 180 brick after the TIU putting 20 amps to the track. Each 180 goes to a Lionel lock on breaker before it hooks up anywhere (overkill). TVS are in place. I only run in command both DCS and Legacy. I do not use a TPC at all. 

 

After watching video and reading all posts I decided 20 amp was too much. Over the weekend I broke my layout into 3 blocks, each powered by a 180 brick into the TIU then to the block. I added SPST switches to power down yards so lighted cars were off as well as engines in the yards. I had been running my entire set up with every piece of track always powered. I have about 175 feet of track. 

 

I never had a problem the old way, ran it for two years almost. I do feel better about the new wiring. Was it worth the effort? 

Originally Posted by Professor Chaos:

That said, I am a little unclear about the statements that a TPC isn't useful for paralleling two bricks.  On some other threads there are dire warnings not to do so WITHOUT a TPC, since the two bricks may not output exactly the same voltage.

If they don't put the same voltage out connected directly to the tracks, they won't do it connected in parallel to the input of the TIU.  What's the difference?  Any problems paralleling them would be identical.

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