On my layout I have a couple frogs at the beginning and end of a gantlet track over the Rockfish River bridge. Often when I run a locomotive through one of the frogs the PSX circuit breaker will trip. This is not consistent, only when a locomotive has passed in the opposite direction. So what is going on? Well first, I have the frogs protected with Frog Juicers. These Frog Juicers are a great option for controlling the polarity of turnout frogs in a situation like this one where a switch machine is not used. These small electronic circuits sense when a locomotive’s wheels contact a turnout frog and the polarity doesn’t match. In this situation the circuit automatically corrects the frog polarity before the booster short circuit detection kicks in.
But why did I get a short only after a locomotive passed in the opposite direction. Well that locomotive tripped the Frog Juicer resetting the polarity. So when the next train came from the opposite direction the polarity was incorrect, tripping the PSX and resetting the polarity. This flip-flop went on until I found out that the PSX was tripping before the Frog Juicer could do its thing–why? Actually, the Frog Juicers are (electronically) very slow. The default trip time on the PSX is about 3ms making it faster than the Frog Juicer, so it will trip first. So how do you fix this? On the PSX set CV55=1 and CV65=128, and the PSX delay will be slower and should work with the Frog Juicers.