I had one of those Marx circuit breakers on my childhood O27 Marx 999 engine layout that worked great. I opened the CB and saw how it works.
Below is a photo of my control panel Marx copied circuit breaker shown on top. The "Reset" red circuit breaker button on a $3, 6 amp circuit breaker wired in series to one of my Lionel LW transformers. The red lens over the "Short" hides an 18 v light bulb that us wired across the two contacts of the CB. When a short occurs, and the CB opens, power is cut to the trains and all the power to the track goes to the bulb and indicates in red a short has occurred.
This works great for my conventional control, post war O27 layout which runs mostly Marx and Lionel trains. I have no modern trains with newer less rugged electronics that may require faster working protection.
I have three such circuit breaker for my 3 Lionel LW transformers and been using them for over 40 years. I uses these 6 amp circuit breakers for two lighting circuits and a switch operating transformer. I do not need to put a light across the CB contacts as I can tell when they throw (lights go out and switches do not operate).