[Jukebox-list] AMI Carriage junction box RR relay arcing

[Steve Wahl]

On Thu, Mar 08, 2007 at 01:14:39PM -0800, Ron Rich wrote:
> Aaron,
>   As for the fuse--AMi did increase the value of that fuse in later
>   production from the 8/10 to a 1 amp SB. 

1. Since it doesn't stick out very much the way Ron said it, I thought
   I'd stress the *SB*, which means slow-blow.  Aaron, if you've been
   using regular fuses there, the slow blow type will probably cure
   the problem of blowing fuses.  (Slow blow lets you draw much more
   current for a very short time period, but blows for a sustained
   high current draw.)  It won't do anything to cure the arcing, but
   it'll at least keep you going while you fix the problem, if you're
   not satisfied to just leave it that way.

2. Esp. to Ron, if this is in the dynamic braking circuit, is there a
   chance that contacts are mis-adjusted?  That is, as I understand it
   dynamic braking puts a dead short across the motor so it stops
   quickly rather than slowing to a stop (and overshooting the desired
   stopping place).  If the shorting contacts "make" before the
   contacts supplying current "break", that would be a quick dead
   short across the power supply, causing a lot more current to flow
   and thus a larger arc when the contacts separate.

   I haven't looked at the schematics nor the actual relay(s) to see
   if that question makes any sense at all.

3. I've heard of capacitors being put across contacts to prevent
   arcing.  Would this be a possible place to apply this idea?  How
   would one choose the propper size capacitor?

Just trying to be helpful, although I'm paying close attention in case
I ever see this on my F, which for the time being is still running
with the original rectifier, to the best of my knowledge.

--> Steve Wahl
-- 
Steve Wahl    steve at pro-ns.net

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