# Electrical protection



## Carl (Feb 19, 2012)

Just a thought for all...............A surge protector seems to be an excellent idea for protecting the electrical side of your layout. In the part of Texas that I live in, we have power surges on a fairly regular basis. The surge protector has saved electrical damage a number of times.


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## MarklinMan (Feb 29, 2012)

Carl,
Very good point to bring up.

Coming from field TV production and being a Hi-Fi buff as well, I can assure you: yes, surge protectors and line conditioners are very good things. 

Your basic house current is not as clean or stable as you might think, and it can lead to a lot of gremlins in different types of gear, depending on surges, brownouts and other interferences.

MM.


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## gunrunnerjohn (Nov 10, 2010)

If you really value your trains, especially the ones with electronics, I'd consider installing a TVS protection diode in each locomotive.

I personally use these for O-gauge stuff: Digikey 1.5KE36CALFCT-ND

The best surge protection is right at the target of the spikes.


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## raleets (Jan 2, 2011)

I am using a high-end audio system surge protector with 8 AC outlets. All of my transformers (3) and lighting power supplies are plugged into it. 
This means I can power up/down my entire layout via one switch. It also means EVERYTHING on the layout is protected from surges and spikes.
We get short term power outages around here at least every couple of months so I feel much better knowing I've offered some protection to my trains.
Bob


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## gunrunnerjohn (Nov 10, 2010)

That doesn't protect individual items on the layout, which is why I use the TVS for each command/control locomotive.


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## raleets (Jan 2, 2011)

John,
I guess I'm missing something here. The ONLY way power can reach the "individual items" on the layout is by running through my VERY high end surge/spike protector. Further, I'm not running DCC, just simple DC on four tracks powered by four seperate MRC transformers.
Can't imagine why I shouldn't feel reasonably comfortable.
Bob


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## gunrunnerjohn (Nov 10, 2010)

If you're running plain DC, you probably don't have a problem.

As for how spikes can reach the equipment past the transformers, that's pretty easy, and it happens all the time. When you have a derailment and a short and draw high current, then remove the short. The flyback effect of the transformer can generate a spike of 100's of volts under the right conditions. Also, any accessory where you're switching it on/off and it has a motor or coil, a similar voltage spike can be generated.


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## JohnAP (May 4, 2011)

Gunrunner,

Will those diodes fit in all scales, and how do you wire them in, inline with one of the pickups?


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## gunrunnerjohn (Nov 10, 2010)

They will work on any scale, and you wire them directly across the incoming power. In the case of HO or N, across the rails. I'm not sure you'd fit this into an N-scale locomotive.


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## JohnAP (May 4, 2011)

Gunrunner,

I have both HO and N, could you show a schematic of how you would install these diodes for each? Thanks, I can't picture in my head how placing a diode "across the rails" would do much for surge protection. I was an Electronics Technician in the Navy, but that was 30+ years ago (closer to 40!) Thanks.


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## gunrunnerjohn (Nov 10, 2010)

I mean directly across the incoming track wires. A transient has to have a common reference, that would be across the rails.


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## JohnAP (May 4, 2011)

Incoming to the power supply, and/or out to the tracks? So the surge energy gets used burning up the diode rather than your equipment?


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## Carl (Feb 19, 2012)

The limited number of folks that I have talked about surge protection, one being an electrical engineer at our local power transmission company, tell me to put the surge protection in front of any electrical stuff that I have for the layout. So, I have mine coming straight off the wall outlet that I use. From there it feeds to the layout power sources, etc. Basically, protect everything.


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## gunrunnerjohn (Nov 10, 2010)

It's not a bad idea, but coming from an EE that designed aerospace equipment for many years, the best place to nuke the spike is right before it gets to the delicate stuff. Many spikes are generated past the input of the transformer, those are the ones I'm trying to stop.


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## Carl (Feb 19, 2012)

I think you are correct. As I now recall, I had a AC powered device on the boat that failed to operate. The repair guys told me that the DC to AC converter had some sort of a problem. Someplace on a model train layout there is a device for going from AC to DC, and that device could develop problems. Now I need to find a power protector that goes on the line, between the transformer and the track.


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## gunrunnerjohn (Nov 10, 2010)

You can use the same TVS that I previously posted there. I put one on every power district output, and also in each command/control engine.


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## plandis (Oct 5, 2011)

I think gunny is right. putting TVS "in front of everything" seems like the thing to do on the surface but it does not protect for a TVS generated from within your layout. those "power guys" have a different way of looking at things. best to do what gunny suggests me thinks...


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