Fast Acting Circuit Breaker for DCS / TIU

Classic Toy Trains Forum
1

Hi all,

I have seen several discussions if there is any fast acting circuit breakers that will work with DCS – TUI. I would like to share with you a project that I built and is working very well. This I did learn of this from “Jim Barrett in the Backshop Volume 8”.

The point of this is not to tell you how to build this, but where to obtain the parts to build this on your own. If you need help, the get the video / DVD and this has very good step by step guide for building this.

The Three main parts are:

  1. Fast Acting Circuit Breaker #W28-XQ1A-10 from Newark Electronics
  2. Binding Post # 35N847 from Newark Electronics
  3. Project box #270-1803 from Radio Shack

You can find Newark Electronics at www.newark.com on the web and order on line. This breaker is used in some power supplies made by both MTH and Lionel.

Wire the breaker on the Hot (center rail) line. The box is good for keeping everything together.

I placed the breaker between the track and TIU. I first had it between the power supply and TIU but moved it. It made more sense to me to have it before the TIU. This way the breaker trips without letting the short thru the TIU.

Hope this helps

tom

2

Now Mth suggests that you place the fuses between the power supply and the TIU

I use Lionel’s 180 W Bricks to power the TIU. The bricks have curcuit breakers; I noticed that the Brick’s breakers trip faster than the inline fuses that I placed btween the Bricks and the TIU

I was thinking of placing Lionel’s TMCC Direct Lockons between the TIU and the track

Alan

3

HI Alan,

Yes you are correct, MTH and OGR both suggest placing the breaker between the power supply and TIU. If the derailment is the cause of the short, and the heat resistance of the short is what trips the breaker, then wouldn’t it make sense to have the breaker as close to the short as possible?

If the breaker is between the power supply and the TIU, then the heat of the short has to pass thru the TIU to trip the breaker. Isn’t this what we are trying to prevent, is overheating the TIU from a short.

Maybe I wrong, but it doesn’t make sense to me.

tom

4

Tom

I see what you are saying; it DOES make sense to do as you are doing; and in addition your way would seem to protect the engine’s circuit too.

However, I learned as an engineer that what is intuitive is not always correct!

A short at the track increases the amperage along the line suddenly and thus the force(amps) of the current. That force originates not at the track but at the current supply side i.e. the transformer, so in effect the TIU sees the rise in amps and first gets damaged ON THE SUPPLY or input side (transformer) not the output side (track).

That is why MTH shows the fuses on the side it does.

Alan

5

Thanks Alan,

This is a good point. Maybe I will move mine back to the power side.

tom

6

Hi All,

I found this and though I would pass it along.

It is from Scotts Odd and Ends.

www.scottsodds-n-ends.com/circuit_breakers.htm

Available in different sizes!!

I have not tried this as I build my own.

tom