Topics

Divide or not

andymsa2
 

hi all,

last night i installed my dcs240 after some initial issues it's working ok now. The issues was it was shutting down imeadiatly with 4 beeps indicating a short. There was no short the shutdown was caused by inrush current. I was surprised at this considering its able to provide at 8 amps, and the current demand is at half of the 8 amps available, I increased the short circuit shutdown time which resolved this, the supply power is the ps2012 so this is up to the job and the current draw is around 4.5 amps which will increase. I should add the dcs240 only powers my signals which are digital and als provides power for the electronics of the accessory decoders. A DC supply provides power for attached accessories.

now I have given an explanation of how I got to this question, I am wondering should I drive the dcs240 to near to at least 3/4 of its full power output, I have wondered if to divided this power with my old dcs100 in booster mode of course.

i look forward to your thoughts

andy

Mark Gurries
 

Inrush current has no numerical value because there are a lot of variables..  But in all cases, it will exceed the current draw of just about any booster made.  The question is how long does it draw this current.  If it exceeds the rating of the booster longer than it shutdown timer will allow, the booster will shutdown.

This problem is no new.  This same EXACT problem happened when sound decoders made their appearance.  The more sound decoder were added to the layout, the worse the inrush current go until the booster could not support it and shutdown.

Today most DCC circuit breakers are design to deal with the high inrush current problem when there is a short circuit.  Recovery problem solved.

To your question, should you drive the DC240 harder.   I understand that changing shutdown increased the inrush capability, but Digitrax has no specification.  This is the same question as “ How many more sound locomotive can I add to my layout".   Every time you add another signal controller, the inrush will go up some amount as you need to charge the capacitors on each additional signal board.  As you keep adding more, at some point your problem that you just solved will reappear.  So it is not how much steady state current draw you can you push, it how much inrush current can the booster support.  There is no valid answer because there is no specification nor DCC standard for inrush in which one can use figure the answer out.


On Jun 9, 2019, at 11:51 AM, andymsa2 via Groups.Io <Andymsa2@...> wrote:

hi all,

last night i installed my dcs240 after some initial issues it's working ok now. The issues was it was shutting down imeadiatly with 4 beeps indicating a short. There was no short the shutdown was caused by inrush current. I was surprised at this considering its able to provide at 8 amps, and the current demand is at half of the 8 amps available, I increased the short circuit shutdown time which resolved this, the supply power is the ps2012 so this is up to the job and the current draw is around 4.5 amps which will increase. I should add the dcs240 only powers my signals which are digital and als provides power for the electronics of the accessory decoders. A DC supply provides power for attached accessories.

now I have given an explanation of how I got to this question, I am wondering should I drive the dcs240 to near to at least 3/4 of its full power output, I have wondered if to divided this power with my old dcs100 in booster mode of course.

i look forward to your thoughts

andy

Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com



andymsa2
 

Hi mark,

thankyou for for the reply and understand your explanation. Leaving aside the inrush issue, the part that f my question relegating to having two command/ boosters was to not have the dcs240 running at near to capacity but to share the load more than evenly.

andy