On Jun 26, 2006, at 10:51 AM, Will Matney wrote:
> Now what if a designer said they'd carry a 40 amp load at 10
> amperes a piece? How long would they last at this output? Would
> Motorola warranty them at this? What kind of reputation would the
> manufacturer get over their power supplies blowing pass transistors
> under full load? Are they willing to replace the product? Are they
> ready for a law suit from a disgruntled customer? The design falls
> back on the engineer, his license, and liability at worse case.
> Where I worked in mining machinery, it occurred often.
In mechanical engineering, they usually refer to this as a "design
rule". For example, light aircraft are typically designed to
withstand 3.8 positive Gs (in the Normal category). But, you wouldn't
build a structure that can just withstand 3.8 positive Gs and then
fail. No, you'd design a structure that could withstand 1.5 to 2.5
times MORE, depending on the materials and construction techniques.
Aircraft are a good example, because that extra strength comes at a
price: weight. Excess weight costs aircraft dearly in nearly every
performance category. The design rule is purposely kept low.
The design rule allows you to compensate for factors that are beyond
your control, such as differences in assembly, deterioration of
materials, improper use, improper installation.
Design rules vary depending on the type of design. Man-carrying
equipment, for example, requires, by law, design rules of 10 or more.
That's why that clip for your tower belt is rated for 5000 lbs, even
though it isn't even likely to see 500 lbs.
The AL-80A and AL-80B have been around long enough to establish a
positive track record. It's pretty clear, that regardless of what the
manual says, these units are not self-destructing because of
excessive plate current.
Bill Coleman, AA4LR, PP-ASEL Mail: email@example.com
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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