Booster Connections & Power

In this section, we provide basic information on boosters, how to install them and potential wiring problem to avoid.


BOOSTER BASICS

DCC boosters were designed as follows

1) Each have their own dedicated power supply.
2) The power supply has a power rating (Voltage and Current) suitable to allow the booster to provide full rated power (Voltage and Current) to the track
3) Where not design to work with "common rail wiring".  (Typically found on larger older layouts running DC with multiple operators.)
4) Have short circuit protection and automatic recovery.
5) Shutdown in the even of thermal overload.

The common goal behind rules #1, #2 and #3 it the goal to eliminate high current sneak paths from flowing down the given DCC control bus from the DCC command station to all boosters.
The common goal around rules #4 and #5 is to make the booster survive the real world of model railroads where short circuits are an electrical fact of life on a layout.


POWER SUPPLY RECOMMENDATIONS

More and more DCC vendors are including the required power supply for the DCC system as part of the purchase.  

At the time of this writing, some DCC systems are still sold without a power supply.   In other words you must purchase the power supply separately.  The minimum power supply requirements are found in the system manual or the booster manual.  Most DCC manufactures sell a compatible power supply so you can still do one brand shopping if so desire.   

In the early DCC days, the most common type of power supply was a simple AC transformer.  However both cost and global green initiatives have created a shift away from the common AC transformer power supply to special high efficiency DC power supply.  DCC manufacture have switched to these new high efficiency DC powers supplies which are technically known as "Switching Power Supplies".  They are basically customized notebook computer AC power supply or "AC adapters" of suitable power levels for DCC.

For information on suitable power supplies for DCC system that do not include a Power Supply, go here: DCC Power Supplies/Xmfrs (US)


NO EARTH GROUND WIRING

Simply put:  Don't connect any part of your DCC system directly to Earth Ground.   Any term "Ground" used in regard to the DCC system DOES NOT MEAN YOU connect it to Earth Ground.  This is the hazard of using the word "ground" instead of the better and more accurate word "common" as in Booster Common.

STATIC ELECTRICITY EXCEPTION:  The only time one may consider connecting the DCC system to Earth Ground is when one is living with high static electricity (Electric Static Discharge or ESD) conditions.  However there must be a high value resistor (anything in the range of 100,000 [100K] up to 1,000,000 [1M] ohm) wired in series with the connection to Earth Ground.  NO solid wire connection.

If you decide to buy your own new power supply, your choices will be mostly limited to a Switching Power supply.   If you pick one of suitable power, make sure the power supply AC input only has a 2 prong AC plug (No Earth Ground).   DCC manufacture have moved to these type of Switching Power Supplies.   Avoid using any power supply that requires a 3 prong plug connection.  The 3rd connection is Earth Ground which is not desirable for use in a DCC system.  

Earth Grounding the DCC system can lead to electrical reliability problems when a device like a computer is connected.  This creates what is called a "multiple common" situation which is electrically a very bad thing to do.  

IMPORTANT DCC WIRING TERMINOLOGY

POWER DISTRICT:  
Addresses the problem of preventing global layout shutdown when there is a short on the track.  It is not unlike the circuit breaker function for your house.  Only the local effected area losses power.

a) Power districts are created from a given booster.   
b) It involves some DCC track current protection device(s) that implements a DCC circuit breaker function.   There are many products out there that do this.
c) Power districts are only useful if you have more than one since the goal it to break the layout electrically into smaller areas.
d) Most useful for layout that have more than one operator or one is running multiple trains at the same time.
e) Using DCC circuit breakers avoids the use of using multiple expensive boosters.  They allow you to take full advantage of the high power available of a single booster which is designed to run multiple trains simultaneously.

BOOSTER DISTRICT
Only applies when there is more than one booster use to run the layout.  

a) Each Booster forms its own Booster District.
b) Each Booster can have its own independent Power Districts.
c) Decision driven by power (Large Scale or lots of moving trains) or the layout is so large that it must distribute booster power to achieve consistent performance.
d) Most layouts do not need a 2nd booster which is why Booster Districts are not discussed. 
e) Many people incorrectly call a given booster district a power district which leads to confusion.
f) All DCC "starter systems" have a booster inside what is commonly called a Command Station.  If there are terminals on the system to connect to the track, it has a booster inside.


MULTIPLE BOOSTERS REQUIRE A BOOSTER COMMON.

This section is about the special wiring required when working with multiple boosters.  This typically applies to only large layouts (Club Size) or large scale layouts. 

Basically any DCC box that has track power terminals to power the track, its from a booster.  This section assume you have more than one box.

If just have your whole layout running on the original DCC box you purchased, you only have 1 booster.   It just built inside the command station.   This section does not apply to you.

IF you have more than one booster, Go here for further instructions: Multiple Booster Wiring


10/14/2015