Shunt diode Barriers

[Clayton]

I need a barrier to meet the following entities:
10.8 millihenries
1.44 microfarads
15 volts RMS
75mA

The people at MTL and pepperl fuchs were unable to find a barrier with
enough current. Any voltage over 6 Volts would be workable and hoping
for current over 40mA. I was wondering if any companies have
adjustable barriers or will custom make some, or if there is some
other way to make the circuit intrinsically safe? And if someone could
explain how the capacitance and reactance come into play here it would
be appreciated.

 

[Spehro Pefhany]

On 14 Oct 2004 12:26:51 -0700, the renowned claytonis@hotmail.com
(Clayton) wrote:

I need a barrier to meet the following entities:
10.8 millihenries
1.44 microfarads
15 volts RMS
75mA

The people at MTL and pepperl fuchs were unable to find a barrier with
enough current. Any voltage over 6 Volts would be workable and hoping
for current over 40mA. I was wondering if any companies have
adjustable barriers or will custom make some, or if there is some
other way to make the circuit intrinsically safe? And if someone could
explain how the capacitance and reactance come into play here it would
be appreciated.

There's probably no way to make something like that intrinsically
safe. You'll need to put an explosion-proof housing and purge on there
or something like that. There are limits for inductance and
capacitance as well as voltage and current flow across the barrier-
the idea is that it should be *impossible* to store enough energy to
cause a spark that would cause an explosion. That's the "intrinsic"
part. The exact requirements (limits) vary with the environment- see
the standards for the classification that you're dealing with. You
can't just put something nasty on the other side of a barrier have it
magically become intrinsically safe- it, and the connecting wire, have
to be incapable of storing much energy, so that limiting the flow
across the barrier prevents anything bad from occurring.


Best regards,
Spehro Pefhany
--
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