# How much power is enough?



## rreiffer (Jan 14, 2009)

All,

I have been wondering how much voltage, amps, power is enough? Is there a reason why we would want to push the envelope on the voltage specification? 

Greg, I know you tend to lead with high voltage, high power DCC setups. What are your reasons for going this direction? Is it the number of trains you desire to run? Is it the speed you need? 

I tend to run logging trains in 1:20.3 scale so speed is not my issue. 

Just looking for some very open thoughts on why you might want to exceed the factory settings of any given device? 

Now please don't take this as being critical of the high voltage, high power group it's just I want to know more. (yes, I am even working on the design for a 25a booster.)

Thanks all.


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## Greg Elmassian (Jan 3, 2008)

I have some extreme grades. 50 cars up 3.4% is about 4-5 amps... that's one train. Not a lot of speed, it's a freight, but remember the train weighs 200 pounds. 

I also have a passenger train, 10 USAT cars, 3 E8's, and with all lights on up the same grade pulls 9.97 amps on the digital DCC meter. 

If it wasn't for the issue of how to handle shorts in trains, I'd have 30 amps available on each main line. 

As it is, I'm using 10 amp boosters and cutting the "main" main line into 2 pieces, and another for the switchyard (because you can have 10 or so locos idling). 

I'll be looking at the new Zimo offering. 

Greg


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## krs (Feb 29, 2008)

As Greg eluded to, the hardest part with the design of a high current DCC booster is how to handle any fault currents. 
Or better how to detect them reliably since the "handling" part is to shut down the output. 

The issue that needs to be adressed is the detection of a fault current at a relatively low power output. 
Say you have a 25 amp booster and you're running a small switching engine with a few cars that draws say 500ma or an amp. 
Something derails and you get a short. 
You want a booster design that detects that short and shuts off the power at say the 1.5 amp level - you don't want the short circuit protection to only trip at over 25 amps which would be the case with a typical over current protection circuit. 
So you need to be able to detect a short at low current levels but still be able to deliver the full current, ie 25 amds in your design, if there is no short. 
The Zimo Central Station and Booster apparently does that - don't know about any others. 
In addition, you also do not want to trip the short circuit protection with every mometary short. 
This all gets a bit complicated when it comes to the design. 

In general, if I were to design a DCC booster, first thing I would do is to write up a set of requirements and have "people in the know" comment. You should have all the requirements clearly in your mind before you even look at the design concept. 

Knut


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