Transient Voltage Suppresion

[Koala]

I am using a couple of old ZW transformers to power up some newer Legecy trains.  I realize the circuit breaker in the ZW is only for it's own protection so adding TVS diodes to each output makes sense to protect the electronics in the engines.  I have two questions.  First does it matter where you place the TVS diodes (at the transformer output posts or anywhere on the track?)  Second, is one TVS diode per output enough protection or would more be better (300 foot mainline?)  Thanks

[lionelsoni]

Actually, the ZW's circuit breaker won't even protect the ZW itself if you get two outputs connected together, since none of the fault current will flow through the U terminals.  In any case, the TVS protects not against overcurrent, but overvoltage, which is what will damage modern electronics.  It doesn't matter where you put it, from inside the transformer box to inside the locomotive.  You need only one per output circuit; but it makes some sense to have one inside the locomotive and one outside the locomotive, so that your locomotive is protected when running on anyone else's layout, and guests' locomotives are protected when running on your layout.

[KRM]

Check this post for more.

http://cs.trains.com/ctt/f/95/p/213224/2337625.aspx#2337625