Surprised derailment didn't trip transformer

Did the derailment cause a sustained short?  

Circuit Protection for your engines and cars should be installed between the Z4000 and track.  When circuit protection is sized according to your load (amps your trains use) the track power will shut down.

The 10 Amp protection in the Z4000 is for the Z4000, not the trains.

Will the TVS from Scott's odds'n'ends do the job as well as the PSX-AC one?

I would like to install a ready-built TVS not wanting to build one from scratch.

Should the TVS be installed between the Z4000 and the TIUs or between the TIUs and the track?

I've read both ways; which one is right?

Already fried one Atlas F unit; would rather not cook another one.

The red light did eventually come on the Z4000 channel, but not before the damage was done.

Thanks!

Thank you!

The TIU already has a TVS across each output, so there's no real need for one there.

I have seen pictures of a few them burned to a crisp.Good idea to open it up and check.

Dale H

Using a 3 or 5 amp PTC Resettable Fuse in line between power supply and TIU will protect TIU and engine.  You can use the PTCs with the TVS if you wish.  The advantage to PTCs is they are inexpensive and there is a wide range of values available.

(PTC Resettable Fuses - AKA PolySwitch, Polyfuse, PolyTron, MultiFuse)

Susan,

I clicked on your link and read with great interest your instructions. My question is what rating PTC would I use for both freight and passenger trains?  

The TVS from Scott's Odds and Ends will do the job but it is too expensive for me to buy. I bought some TVS units from Mouser Electronics a couple of years ago and paid around $12.00 for 15 bi-directional 32 volt TVS units, with shipping included.

Lee Fritz

I can not say what the MTH Z-4000 has for circuit breakers or how it works. Let's hope the Z-4000 has a decent current protection on it as it is much newer then the p.w. ZW.

The Lionel post war ZW has a 15 amp circuit breaker hooked up to the common side outputs, so you can almost weld with it before it throws the breaker. My 2 cents!

Lee Fritz

3 to 5 amp?  That seems a bit low to me.

3 or 5 amp is low.  That's why I like to use the PTC Resettable Fuses.  They're inexpensive and if one value doesn't hold the load, I can easily switch to a higher value until I find the lowest value that will hold the load.

If you have to use the 9 and 10 amp ratings to hold passenger train loads a 2 -3 amp PTC Resettable Fuse can be installed in an engine's power supply line for maximum protection.

That makes more sense as it's pretty normal to have more than one consist on a single TIU channel.  Of course, if all the cars have LED lighting, they might be enough.

CIRCUIT BREAKER PROTECTION FOR THE Z4000 OUTPUTS (TIU INPUTS):

I have built custom made circuit breaker boxes to protect the Z4000 outputs. The breakers are 10 amperes each. 

I also have 5 ampere circuit breakers with voltmeters on the outputs of my TIU.

Each feeder to my track also has an individual 3 ampere circuit breaker. The circuit breaker box shown has 10 individual circuit breakers for my track feeds.

These circuit breakers interrupt short circuits only within a block.

Note 1: All my passenger cars have been converted to LED lighting so that the current requirements for passenger trains is much lower than with incandescent bulb lighting.

Note 2: All my turnouts use AUX power (not track power) so there is no additional track power required for switching.

ADDITIONAL EMERGENCY SHUTDOWN CIRCUITS:

I have two ways to shutdown power to the tracks in an emergency.

1. I have a wireless control which I can use to remove power to the TIU inputs in an emergency. I can carry this on my belt when I am anywhere in the room. This control only removes 12 volts to my trip circuit.  This action does not affect power to my Z4000 or any other power source.

2.  I also have emergency stop (E-Stop) buttons mounted along the outside of my layout which will also shutdown power to my TIUs. These would be used if there was a derailment and a possible collision on the track. I have made 4 E-Stop boxes for this purpose. Anyone standing near the layout can hit one of these E-stops and shutdown power. (I can also set a switch to bypass these E-stops and prevent their use if necessary.)

POWER SYSTEM PROTECTION:

I have individual circuit breaker protection on all 120vac to my transformers.

I have the following various transformers:

2 MTH Z4000 transformers

1 Lionel ZW transformer

4 Lionel KW transformers

1 MTH 75 watt brick.

1 Lionel 80 watt transformer

1 custom made AC power source