I’ve read many of the posts about adding a TVS to wiring. One that was recommended was the 1.5KE36CA. From looking at the datasheet, the breakdown voltage is right around 36 volts. I run older locos ('20’s -30’s), and I’m using a type R transformer (because it goes to 24V).
In light of that higher output, would I need to choose a different TVS with a higher breakdown voltage (e.g. 1.5KE43A)?
Also, can I just install this by wrapping the leads around the terminals on the back of the transformers?
On a related matter, how would one determine the rating for an added inline breaker on a circuit? I have no idea what the current draw might be for one of these locos, or for a train with 5-6 lit cars.
The peak voltage is the RMS voltage (24 in your case) multiplied by the square-root of 2. This is 34 volts, still under 36 volts. However, there is virtually no risk in going to a slightly higher rating and you eliminate any worry about the tolerance of the part; so go for it.
However, be sure you have the correct part number. I notice that your example is the 1.5KE43A. That is a unidirectional TVS, which is useless for an AC circuit and which your transformer will probably destroy immediately. The “C” in the part number is essential, to get a bidirectional TVS. So “1.5DE43CA”.
Yes, the back of the transformer should work fine.
It is hard to estimate the electrical load of a train. But I usually go with 5 amperes. You should be able to find breakers with 5-ampere and 7-ampere ratings.
Crucial typo, that was.