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Protecting Against Short Circuits

Posted by on Dec 19, 2014 in Miscellaneous, Tony's Tips |

Electrical short circuits are one of the major concerns when operating with Digital Command Control.

DCC boosters provide first line of defence against shorts. When a short circuit occurs on the layout, it will draw more Amps than typically needed. This will be sensed by the booster which in turn will trip the breaker.

Most boosters will reset automatically in a second or two. But the part of layout where a short has occured will stop operating until the short has been corrected. To avoid having the entire layout shut down, divide it into sections.

Why Shorts Happen?

1. Poor Wiring
The short caused by poor wiring may be nearly impossible to find. The best, but seemingly drastic, solution is to rewire the entire layout and doing it carefully.

2. Driving a Train Into A Block of Track Where a Turnout’s Points Are Set Against It.

3. Freight Car or Locomotive Whose Metal Wheels are Out Of Gauge (or derailed)
coming into contact with the point rails when they pass through a turnout.

Turnouts With Non-Insulated Frog

The frog with non-insulated turnouts should be fabricated from rail and connected to all adjoining rails.

The most common form of short circuit happens when train enters the turnout from the frog and is driven past tan electrical gap. If the turnout’s points are set against the direction on which the train is traveling, the loco will “bridge the gap” between the electrical block it is leaving and the electrical block it’s entering. The locomotive becomes “confused” because one set of wheels is receiving power differently than the other set.

As a result, every train in the booster’s district will stop. Until the train is moved away from the turnout or the turnout is thrown so the points are in correct position, a short will occur.

Turnouts With An Insulated Frog

Insulated frog turnout means that the frog is plastic or cast metal completely insulated from all adjoining rails.

A short will happen when a train enters a turnout from the frog end and the points are set against the direction in which the train is traveling. The train will continue until it gets to the points, eventually derailing and fouling the turnout.

As a result, every train in the power district will stop.

Controling Short Circuits

You will never be able to completely eliminate short circuits. The only really effective way to reduce the effect of shorts circuits on your railroad is to divide it into power districts. Dividing your layout into power districts by adding more boosters is the simplest way to control the effect of a short circuit on the rest of the layout. More boosters will also ensure that each power district has enough amperage to control all the locomotives, switch machines, and other accessories.

You can avoid purchasing additional boosters and still section your layout by using PSX DCC Circuit Breakers and Reversers.

Adapted from “DCC Made Easy”, by Lionel Strang, with permission of Kalmbach Publishing Co.