@gunrunnerjohn posted:As I've frequently said, the absolute best place for the TVS is inside the locomotive directly across the track power feed. Obviously, this is also the hardest place to install them, and you have to modify every locomotive. Of course, while you're in there, you can add the 22uh choke in the track power feed for any TMCC/Legacy locomotives to minimize any effect the their electronics on the DCS signals. If you choose to do that, the best way is to put the choke in the center track feed and then the TVS diode across the feed after the diode. That way the DCS signal isn't significantly affected by the bulk capacitance of the TVS diode in the locomotive.
John, Thank you for your reply. I do remember your previous assertions about the best place inside a locomotive to install TVS diodes would be across the track power feeds and your cautions about excessive TVS diodes diminishing the DCS signal. This assertion combined with thinking about @Adrian!'s recent explanation (quoted above) I'm wondering if the following may be better on a non DCS layout and if not, why?
If motor coils are one of the primary sources of voltage spikes in a derailment scenario, wouldn't clamping these spikes at the point where the motors connect to the motor driver board reduce the spikes before they pass through all the circuit boards' electronics on their way to previously suggested TVS diodes connected at the other side of all those electronics at the track pick-up connections?
As I understand it, another major source of voltage spikes in the derailment scenario would be from the transformer coils. So in addition to installing TVS diodes on the loco's motor driver side of the locomotive, also connecting TVS at the transformer outputs would seem to be optimal (non DCS), as well as accross each accessory with coils.
