Ken Finney wrote:

snipped


I knew I was too close to the problem, and that there had to be a simple
solution. Your solution is likely what we will use.

As for the why, we are testing a switch to ensure it won't set off an
explosive atmosphere. The test method isn't too clear other than we need to
test the switch at maximum current into an inductive load. Rather than try
to justify why this really means "a partially inductive load", we'd rather
worst-case the test conditions.



Now, even more than I posted to this thread an hour ago, I think you
really need to find out just what inductance the authority governing the
certification on your "switch" requires for that test, and also the
composition and temperature/pressure conditions of the "explosive
atmosphere".

It sounds like a job for UL, Factory Mutual or CSA to me.

Years ago I used to design "intrinsically safe" monitoring circuits for
use in hazardous locations like the inside of gasoline storage tanks and
had to get my stuff certified by actual tests at those three agencies.

They had pretty involved standards and procedures for testing such
things and used carefully controlled mixtures of gasses and air they
tried to get our stuff to set off. The same kind of gas test cells along
with standardized loads were used for testing "explosion proof"
equipment such as switches.

So forgive me if I'm misunderstanding your requirements, but the answer
to your question may not be as simple as you hope it is, particularly in
today's litigeous world.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"