New Railway Modellers Forums

A thought, live frog points and diamonds present ample opportunities for the goblins of short circuits to come out to play.

While this can be managed, especially in a human (or leopard) driven layout unless the driver wanders off to lay in the sun somewhere mistakes can and will occur. add in automation to the mix and the potential is partly mitigated but also partly masked and likely to lead to problems somewhere.

many DCC systems will detect and cut out when a short occurs, however thoughts move to "prevention is better than cure" - this off the back of wondering about reverse loops and twitching at the idea of creating a short so it can be detected and corrected.

on Leopard Street yesterday I wired up a diamond crossing with two points. all electrofrog, typical double junction. the first idea was each point switched its own frog and also one of the diamond ones. it is quite simple to see a situation where a train is manually driven towards the crossing with the points set incorrectly due to driver incompetence. the crossings will now be controlled via relays.

I'm planning to experiment with some electrical interlocking, the idea being to insert a second relay, a DPDT one, to manage the crossing. thus not only can the frog polarity be reversed the whole crossing can also be physically isolated electrically. thus when the points are set so no trains will enter the crossing or there is the chance of a collision the whole crossing can be powered down.

now that won't stop a train pushing unpowered vehicles over it, nor will it stop a train driving on to it, but it should stop short circuits.

said interlock signal for "conflicting movements" can also be used to trigger signals and the associated automatic brake circuits on the approach.

from all of this the question is thus, for those who use electrofrog points, how much of a problem have you found short circuits to be?

Most common cause of shorts on Electrofrog points is because you drive a train into them set the wrong way. If the frog were Insulfrog, for instance, the train would not cause a short but would instead almost immmediately derail with the blades set against it. The short might be a pain, but at least it's preventing a derailment.

oh for sure I know why, "operator error" with going against incorrectly set points, or with the case of a diamond going when its not switched correctly. the idea, mostly for the diamond, is to power the whole thing down to avoid the short - with a loco leading likely also stop the thing before it hits the presumably incorrect adjacent point.

though on the approach from the trailing end I plan to have braking modules and signals anyway, which should catch automated and manual trains.

this is more about when say at a double crossing both routes are set across the points. one or other frog will be wrong and there is the chance of collision

this isn't going in in the first instance, but will be retrofitted later to check if it works as I expect, sort of defensive design, which I'm hoping combined with block detection will provide some suitable interlocking to prevent derailments