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Derating of resistor/capacitor

P

Pon

Jan 1, 1970
0
How to derate a resistor in series,parallel resistor in a signal
Similarly for a capacitor in series, parallel.

Is there any standards / formulae of the derating of
Capacitors,Resitors, and inductors?
 
P

Phil Allison

Jan 1, 1970
0
** Yawn - more Google Groper crap !!

How to derate a resistor in series,parallel resistor in a signal
Similarly for a capacitor in series, parallel.


** What does this arrogant, GG wog idiot think the term "derate" means
????

Maybe this uppity DARKIE would care to en-LIGHTen us all.

Don't hold your breath.






....... Phil
 
J

Jon

Jan 1, 1970
0
Pon,
In the aerospace industry it is common to derate resistors and
capacitors to 70% of their room temperature power, voltage ratings
respectively. This varies somewhat depending on the type of component.
All resistors have a temperature derating spec. It is usually
specified as something like "Derate X% per deg C above 70 Deg C". For
more on derating of components, see
"Parts Derating Requirements and Application Manual" AFSC Pamphlet
800-27. This publication is available from Global Engineering
Documents.
 
K

Klaus Kragelund

Jan 1, 1970
0
ehsjr skrev:

Actually it is a good point. A robust design is best implemented with
margin from the datasheet limits. The trouble is that one does not
always design the circuit optimum in this case. For example if the
datasheet limits really are limits - or if the designer of the part has
used his/her own derating rules.

In our company we have been designing accordingy to the conservative
space derating rules (derated power to 60%, voltage to 80% current to
80%)

For example for a ceramic capacitor this would perhaps be overkill
since I have never seen a ceramic cap damaged by running at 100%
voltage rating. Anybody else have experience of this?


Regards

Klaus
 
P

Pooh Bear

Jan 1, 1970
0
Klaus said:
ehsjr skrev:


Actually it is a good point. A robust design is best implemented with
margin from the datasheet limits. The trouble is that one does not
always design the circuit optimum in this case. For example if the
datasheet limits really are limits - or if the designer of the part has
used his/her own derating rules.

In our company we have been designing accordingy to the conservative
space derating rules (derated power to 60%, voltage to 80% current to
80%)

For example for a ceramic capacitor this would perhaps be overkill
since I have never seen a ceramic cap damaged by running at 100%
voltage rating. Anybody else have experience of this?

I've seen 100n MLC's rated at 50V 'burn up' when used for decoupling on 30V
supplies. It just happens occasionally. I concluded that it was 'inrush current'
as the psu switches on. Polyester 100V ( mylar wound ) types were better but
still failed once in a while.

Graham
 
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