HomeRoast Digest


Topic: Caffe' Rosto profiling >was Re: +Puerto Rican Yauco Selecto City (2 msgs / 56 lines)
1) From: Jeffrey A. Bertoia
EskWIRED wrote:
<Snip>
Go oversized.  SCRs/TRIACs tend to fail shorted at least until they burn 
out.
<Snip>
If the fan was in series and it draws 2 amps at 20 volts that winding is 
(v*i = 100*2 ) 200W.
<Snip>
Making the same assuptions from above the winding is about 50 ohms 
making the new power
(v*v/r = 120*120/50) 288 watts.  Be careful, that's about 40% more power 
than rated.  In general
good design practice is to leave 20-40% margin on an item like that.  So 
you'rw right at the limit if
not over.
The surface temperature of the element will increase substantially also, 
potentially endangering the
element holder and case, and thus your workbench, home etc...
<Snip>
Please also consider this in rev 2.0 also
jeff
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast

2) From: Jeffrey A. Bertoia
EskWIRED wrote:
<Snip>
No actually I was referring to the heater winding.
<Snip>
Again I was referring to the heater winding.
<Snip>
As long as you are right there it is probably not an issue.  But the 
roaster may eventually melt.  There is
very little question that the smaller winding will fail in significantly 
less time than it normally would.
<Snip>
Total wattage would be original wattage + 88  (additional wattage from 
the short element) - 40 (watts
for the fan).
jeff
<Snip>
-- 
Jeffrey A. Bertoia                      jbertoia
Slalom Services, Inc.                   www.SlalomServices.com
Telephone: +1 (810) 220 - 1174          Mobile: +1 (586) 854 - 7312
homeroast mailing listhttp://lists.sweetmarias.com/mailman/listinfo/homeroast


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