Hello all,
I am finally starting to add TVs diodes and separate circuit breakers to my layout, both at the transformer and the tvs' at various locations around the track. My question is if I do have a voltage spike issue does it blow the tvs' which would make it necessary to replace them obviously? Please advise.
Also, I will be adding 3 amp + 5 amp three wire circuit breakers. Please vice how to hook them up to the transformer.
Thank you very much, Jerry
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The TVS doesn't blow because of a voltage spike, unless it's a really big one that exceeds it's max rating. They will degrade over time, but it will be years before they need replacement. The only way to really test them is with a fairly complex test setup, so if you're nervous, just put a date on the install and swap them every three years. 
You want the TVS across the power as the last thing in the circuit, past any circuit breakers.
John,
Any comment on using this "array" as opposed to the ones we have been using? Better? Not sure if this is a few diodes in series? I know you can figure it out thought. :-)
Apples and oranges, that's not really suitable for our requirements. It's also a 600W instead of a 1500W part as typically recommended for the model train application. Did you check the features?
Littelfuse SM712 Series TVS Diode Array is a 600W Asymmetrical TVS diode array designed to protect RS-485 applications with asymmetrical working voltages (-7V to 12V) from damage due to electrostatic discharge (ESD), electrical fast transients (EFT), and lightning induced surges.
Stick to what works, this is a different application. 
Dear Jerry
Here is an article you might want read up on TVS.
http://www.jcstudiosinc.com/TV...ar-Layout-Protection
John is there a max distance for the TVS from the circuit breaker?
No max distance from the breaker, the closer to the device being protected, the better. For track, I'd put them right on the track feed. If you have a terminal block with multiple drops, put it at the terminal block.
Thanks John.
Thanks all, & a merry Christmas to all.
Best, Jerry
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