[RE-wrenches] Transformer inrush

[William Miller]

Friend:

Thanks for the responses.  They have all been valid on offered good 
options.  There is one possible solution that will be easier to implement 
and is worth a brief description here:

Breakers have an AIC (Ampere Interrupting Capacity).  This is a 
quantification of how much fault current a breaker can handle before it 
explodes (in lay terms).  Residential AC power distribution drops have a 
finite ampacity under short circuit capability.  Sure, you drop a wrench 
across a bus expect a lot of amps to flow until your main opens.  A higher 
amperage commercial service can deliver more instantaneous amps, so a 
breaker with a higher AIC is required in commercial applications.  Typical 
values are 10,000, 22,000 and 65,000.  The lower values are found on garden 
variety breakers.

I have learned that the higher AIC breakers also have a higher 
"instantaneous trip" value.  A Siemens 2 pole 100 amp breaker with a10,000 
AIC rating has a 600-900 amps instantaneous rating.  The same breaker with 
a 22,000 AIC rating has a rating of rating of 1,000 -1,2000 instantaneous amps.

I am thinking that the higher instantaneous rating my prevent nuisance 
trips.  My supplier has asked Siemens to comment but we receive a very 
non-committal answer.  My supplier has offered to sell me breakers with the 
higher AIC and accept them back if they don't solve the problem.  That is 
the direction and I will report back.

Thanks again.  I hope this exchange was beneficial for many of you and 
prevents some of you from repeating my mistakes.

William Miller
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachments/20100513/678212e6/attachment-0004.html>