Why do I need a breaker? Myth vs. Fact

You can have a short circuit in a decoder but there is no guarantee it will trip a DCC circuit breaker or shutdown a booster.

 

Myth:  DCC circuit breakers protect decoders.

 

Fact:  DCC circuit breaker protect boosters.

 

The goal of the DCC circuit break is to protect THE BOOSTER by isolating the short locally within the breakers power district so the booster can remain powering the OTHER power districts to keep the other parts of the layout running.

 

For the DCC circuit breaker to act, a short circuit has to meet specific criteria.

 

a) The short circuit current must be above the trip point of the DCC circuit breaker.

b) The short circuit current must last for a period of time.

 

There is nothing in the design of a given decoder that is designed to comply with these requirements when they fail.  Failure is not a design parameter.

For the Powercab Starter Set you are limited to the CP6 ONLY.

ALL other boosters and command stations can use the CP6 or the EB1.

*** Note - If you have a Powercab and a Booster remember that the Booster is now what is running trains NOT the Powercab.

The SB3 and DCC Twin are 3 amps and can use the CP6 or the EB1.

The SB3a, SB5, and all Power Pro systems are 5 amps and can use the CP6 or the EB1.

You MUST use some form of Protection!

The SB5 and Powercab have built in over current sensing for basic self-protection that will continuously try to reset until destroyed if left uncorrected. They do not have manual breakers that will trip or fuses that will blow.  

The reason you would add protection of some sort is that you don’t want the entire railroad to shut down if you have a short. You break it up into smaller pieces. All of our systems including the Powercab will only protect itself and not your locos. Use the CP6 or Multiple EB1's to divide up your layout and protect your trains! Think of this like the breaker panel in your house.

Basic current limiting via the CP6: You get 6 sections (power districts) outputs each protected by an 1156 bulb that limits current to 1 amp per section without shutting down the other 5 sections.

Electronic Circuit breaker EB1 - NOT FOR USE WITH POWERCAB . The EB1 provides true electronic protection that is configurable for reaction time, overload limit and reset. Protects one Power District.

CP6 - https://ncedcc.zendesk.com/hc/en-us/articles/201045719-CP6

EB1 https://ncedcc.zendesk.com/hc/en-us/articles/201400305-EB1-Circuit-Breaker

 EB1 vs. CP6

Short circuit protection is done different internally between systems. This is due to the construction of the power supplies in the Powercab and the PH Pro.

The EB1 has no current limit protection. A single block item. It will draw the full current capacity of the booster if dead short. It cannot be set low enough to be used with a Powercab. Lowest breaker setting on an EB1 is 2.5 amps.

CP6 is a current limiting device. Full 2 amp in from Powercab, output is 6 - 1 amp power districts with current limiting. Bulbs are in series with load. CP6 will not make Powercab reboot. Will allow 1 amp to pass thru, rest of load (up to 12 amps) will burn off as heat / light. Multiple sections of CP6 can be used in parallel to create larger limits. 1.75 amp bulbs are available.