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[AMPS] Fw: ICAS rating confusion.

To: <amps@contesting.com>
Subject: [AMPS] Fw: ICAS rating confusion.
From: W8JI@contesting.com (Tom Rauch)
Date: Tue, 30 Jan 2001 13:38:25 -0500


> Just what is ICAS rating when compared to CCS.
> Is there an agreed upon standard? 


I haven't seen a standard for ICAS. The rating difference is a DUTY 
CYCLE rating change, not a current rating change. In other words, 
if you draw 800 mA from a bridge you spec the transformer for 800 
mA dc load with a bridge rectifier and then say something like 
"ICAS 50% duty cycle with maximum load period 5 minutes". If 
you don't spec it in detail, the transformer will be underbuilt or 
overbuilt for some load conditions.

Multiplying current times a "fudge factor" does NOT work, because 
of the many variables involved. 
     
When I spec transformers, I spell out the duty cycle of each 
winding as well as the maximum ambient temperature and air flow 
rate. Beside load current, maximum ESR of the HV winding is also 
spec'ed. It's actually an involved process.

I often even tell the manufacturer which winding lays over which 
other winding, so that inrush is limited and regulation of critical 
windings is less impacted.
73, Tom W8JI
w8ji@contesting.com

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