Not so fast there

The PSX power managers and other kinds of circuit breakers are popular for dividing a layout into several sections, and prevent the entire layout from shutting down in case of a short circuit. These units are designed to trip before a command station or booster’s short detection circuitry can act. However that approach is dependent on the circuit actually being more sensitive and acting faster than that of the command station or booster. If instead it is slower, then the command station or booster will shut down first.

I ran up against this while installing a PSX4 with my Digitrax DCS100 command station a couple years ago. I ran a switcher through a closed turnout to test the setup and sure enough the command station shut down instead of the PSX. Fortunately, there is a way to prevent this from happening. Digitrax units have OpSw settings that can be used to customize their operation. In this case OpSw 18 comes in handy.

Under the default setting for OpSw 18 the command station’s short detection circuit will shut down faster than the PSX4. The solution was simple, just change OpSw 18 to its alternate setting which results in a slower reaction time of 1/2 second. This gives the PSX time to shut down the block with the short and keep the rest of the layout running. So if you run into a situation like this, no matter what DCC system you own, check to see of there is a way to change the sensitivity, it may save you some headaches.

The same thing can happen with a Frog Juicer. These are slower to act than the PSX units. Consequently, the PSX can trip before the Frog Juicer has a chance to correct the polarity of a turnout frog. The solution is to slow down the PSX and give the Frog Juicer enough time to do its job. On the PSX set CV55=1 and CV65=128, and the PSX delay should work with the Frog Juicers.

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