This section talks about how DCC Booster and DCC circuit Breakers work in terms of protecting our equipment. It also applies to how Decoders can drive motor efficiently.
BASIC PHYSICAL SOLUTION: If you limit the time duration that the current flows, you can then limit the temperature rise of any device or wiring that is involved in the current's path. If you can keep the temperature rise below any destructive temperature of any devices or wiring involved, you will not cause any damage to the device or wiring.
KEY PART OF THE BASIC SOLUTION: DCC Circuit breakers set to a trip threshold of 5A or below will limit the TIME duration of the any current flowing above the trip threshold. DCC CIRCUIT BREAKERS DO NOT LIMIT THE ACTUAL CURRENT. The booster does that all by itself. DCC Circuit Breaker "BREAK THE CURRENT" which is why they have that name in the first place. To be clear, the full current of the booster will flow through the DCC circuit breaker to the load or short circuit. Some heat will still be generated. The question is how much and where.
KEY PART OF THE BASIC SOLUTION RELIABILITY: The weakest point in the current path that has the highest resistance will see the majority of the heat. Stated another way, any wiring or connection that is to weak to work with the high current rating of the booster reliably can become thermally damaged. Hence when you go below HO, the wiring and connections inside the locomotives involved become to weak for high current. The heat can become so concentrated so fast it will find a single point of potential failure. I have seen the wire insulation melted in a HO locomotive even though it did not reach the point of burning. It is a time bomb waiting to happen. So the limiting the scale to HO or above and make sure all the wiring is designed for high current where ever possible will minimize that risk.
LONG EXPLANATION:
CURRENT: In the electrical world, current is what does the actual work for that involves actual "electron current" flow. It is the movement of electrons.
ENERGY: Voltage (V) is just the Potential Energy. Voltage put pressure on the current (I) to attempt to force it to move through resistance (R). Current cannot flow unless there is some voltage present and a complete circuit for it to flow in. [Ohms law says: V = I * R]
POWER: When current is forced by the voltage through a given resistance, it converts the potential energy into "work" given in units of Watts. It is a unit of energy. Watts is also known a Power (P). [Power = P(watts) = I^2 * R]
When you have Power/Watts present over time, it create heat.
The damage starts with heat. If one has enough heat, it can do anything from burn your fingers, melt plastic or at worse start a fire.
In other words for a given votlage, current = heat. More current = more heat.
When we talk about heat, we are talking about Watts. W = V x I. A low watt soldering iron puts out less heat than a high watt soldering iron.
Heat Energy is watts over a period of time. We call this Watt/Seconds or Joules.
We also know from life experience about the mass of the object and it ability to absorb heat.
We know form experience, the large the mass a given object has, the more heat it takes to raise it temperature. It is not unlike the boiling water in a pot on an electric stove. For a given burner size (watt/current rating) a small pot of water will come to a boil faster than a big pot of water. to get the big pot to boil as fast as the small one will take a bigger burner (Higher watt/Current Rating.
the bigger the pot, the more time to get the temperature to the boiling point unless you put it on a bigger burner.
Everything has mass to it and like all object, mass can accept or disapate heat. The whole idea be