Hi Jim,
You are absolutely correct.
Many clients want to know at what the threshold level the E.U.T. 
exhibited degradation
before/or component failure. Don't forget about EN61000-4-4 Electrical 
Fast Transients
Best Regards

-----Original Message-----
From: Jim Hulbert [mailto:hulbe...@pb.com]
Sent: Thursday, August 19, 1999 10:07 AM
To: emc-p...@ieee.org
Subject: EN50082-1:1997 & EN55024





Immunity test standards EN50082-1:1997 and EN 55024 call out the basic 
standards
EN61000-4-2 and EN61000-4-5  for ESD and Surge.

EN61000-4-2, Section 5 starts out "The preferential range of test 
levels for the
ESD test is given in table 1.  Testing shall also be satisfied at the 
lower
levels given in table 1."   EN61000-4-5, Section 5 contains similar 
wording.
This is how we perform our compliance tests.   We start at the lowest 
test
voltage levels from the respective tables and step up to the test 
levels called
out in EN50082-1/ EN55024 (or higher, depending on our own in-house 
product
spec.)

However, I have noticed that some test labs go straight to the levels 
called out
in EN 50082-1/EN55024 and skip testing at the lower levels.  I believe 
this
approach is incorrect because it does not conform to the requirements 
of the
basic standard and is simply not a complete test.   As explained in 
EN61000-4-5,
the non-linear current-voltage characteristics of the equipment under 
test
should be considered and the test voltage should therefore be 
increased by steps
up to the test level specified in the product standard or test plan. 
  The same
rationale applies to ESD testing where current-voltage characteristics 
are also
non-linear.

How do others approach these tests?  Are we adding unnecessary test 
time by
starting at lower test voltages and stepping our way up or are the 
test labs
that go straight to the maximum test levels overlooking an important 
aspect of
the testing?

Jim Hulbert
Senior Engineer-EMC
Pitney Bowes



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