Circuit protection for SB5

[gregc]

wdcrvr

My thought being that if a short occured in one zone, that 1156 bulb would draw the power and shut down just that zone while the other zones would still be up and running?

yes, and if there were shorts in multiple zones, the EB1 would protect the SB5

the 1156 bulbs limit the current (~2.1A)

245

[wdcrvr]

Thanks for all the inputs.  Just for the record I do understand that the SB5 is now the power source and the power cab is acting as a controller.

Update:  I am somewhat confused by some comments to just rely on the internal circuit protection in the SB5?  The story here is that I was using the SB5 when a short happened in the layout.  Because (as was later explained to me) I did not correct the short or shut down the power quick enough, the SB5 shorted out.  After testing all other possibilities it was obvious that the SB5 was shorted internally.  I sent the SB5 to NCE and they graciously repaired it at no charge and had it back to me in about 6 weeks.  I was very happy.  Then, 2 days after I got it back, I foolishly let my two grandsons each run a train of their own at the same time.  I let myself get distracted and involved in a conversation with the eldest whilst the youngest ran his train into a turnout that was thrown in the wrong direction.  This, of course, created a short, which I was not aware was happening.  So, because I had not put any protection between the SB5 and the track and did not quickly clear the short, the SB5 once again shorted out internally.  Now I was no longer happy.  Fearing the worst, I sent the SB5 back to NCE again.  They sent it back to me in 4 weeks, again fully repaired and again at no charge.  THREE CHEERS FOR THE NCE FOLKS.  Such amazing service!!  However, this time they added a page to the no charge invoice they sent me.  They really emphasized that you should always some form of protection.  "Myth:  DCC circuit breakers protect decoders.  Fact:  DCC circuit breakers protect boosters."  I have learned my lesson and have ordered an EB1 circuit breaker. 

So, now I am wondering, after I install the EB1 to protect the SB5, could I then later break up my layout into several seperate zones and have them individually protected by putting a 1156 auto bulb in series for each of the zones.  My thought being that if a short occured in one zone, that 1156 bulb would draw the power and shut down just that zone while the other zones would still be up and running?

Sorry for the long drawn out story.  Hope no one fell asleep before they got to this point.

I really appreciate this forum and all of the people out there who give so generously of their wealth of information.  There really isn't anyone around me that I am aware of that could answer my many questions.

Thanks

wdcrvr

[gregc]

Renegade1c

The internal circuit breaker on the Power cab and SB5 will actually turn power off to prevent components from heating up and having this issue. 

when used with an SB5, the power cab does not provide track power and is simply a controller.   the SB5 becomes the command station and booster

[gregc]

the 1156 auto bulb draws ~2.1 A.   the NCE SB5 can provide 5 A

if 2 locos operating at the same time draws less than 2 A, there's no need for 5 A and a single 1156 bulb would work.

more likely, you can divide your layout into several power districts (easier to locates shorts), each with an 1156 bulb in series with the track limiting the current to each district to ~2A.

presumably, the SB5 will shutdown if 5A is exceeded.   so you could have 4 power districts, each limited to ~2A each.   but the sb5 would shut down if the total power drawn by all districts excedes 5A

 

[Renegade1c]

Both units have on board short circuit protection. Let the internal protection do its job unless you are trying to break up layout into seperate power districts in which case there are many choices of circuit breakers. 

Bulbs just create a zone of known resistance that is typically greater than any other location and output it as light and heat in case of a short. It doesn't prevent short or kill power if a short occurs. If another component ends up having a higher resistance than the bulb it was generate heat and melt. We had this happen on one of club locomotives when it was left for a few minutes. The truck on the loco melted but the bulb never came on to indicate a short. 

The internal circuit breaker on the Power cab and SB5 will actually turn power off to prevent components from heating up and having this issue. 

Not trying to dissuade from doing it but its a method better suited to DC operations than DCC since DCC has live tracks all the time. 

 

[wdcrvr]

With an NCE Power Cab system with an SB5 booster, what type of auto light bulbs should you use to protect the system from damage due to short circuits?  And is one bulb enough or should you use more than one?

thanks

wdcrvr