AMETEK CTS 3.0 - Manual (Page 21)

User Manual Compliance Test System 3.0
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2.2.1 Why do you have to test?
In general, these IEC directives do not have the legal force of law. However, the European Union
(EU) has issued Euro Norms in the context of these IEC directives that are legally binding and are
enforced by the EMC Police. The relevant enforceable standards are IEC 61000-3-2 and IEC
61000-3-3, which supersede EN60555.2 and EN60555.3 respectively. These standards are also
known under the IEC designator IEC 61000-3-2 and IEC 61000-3-3. Recently, the universal IEC
61000 convention has been adopted for all IEC standards.
Individual member countries have issued identical national norms, either in their native language
or in English, which carry the same legal enforceability. Other countries such as Japan and the
USA are in the process of adopting similar standards. Penalties for violating these norms range
from hefty fines to jail time. In cases where the manufacturer is not located in the EU, his
distributor or authorized agent will be held liable. Local customs agencies can stop equipment that
does not meet these IEC norms at the border. Compliance testing of equipment is performed by
accredited laboratories run by European government agencies assigned with enforcing these
norms. Also, competing vendors have been known to submit failing test results on competitors'
products to local governments to force prosecution and gain a competitive advantage in the
market place.
Conformance to the EMC low voltage directive is indicated by the CE mark. Note however, that
the CE mark includes MORE than just IEC 61000-3-2 and IEC 61000-3-3.
2.3 The IEC 61000-3-2:2000 Standard
This standard is often referred to as Amendment 14. It is less stringent for class C and D products
compared to the 1998 standard. Effective January 2001, products may be evaluated against this
standard.
2.3.1 Test Classes
CENELEC-A14 changes the definition of Class-D products. Per the amendment, only TV‟s, PC‟s
and PC monitors are to be tested per Class-D limits. This means that many products migrate to
Class-A. Note that there is no change in classification for Class-A, B, and C products, but the
harmonic analysis method for products with fluctuating power is affected by A-14 for these
products as well.
The limits for Class- C & D are proportional. Whereas this doesn‟t cause any difficulties for
products with a constant current/power level, the situation was less clear for products with
fluctuating load levels. Most test systems implemented so-called dynamic limits, with the limits
constantly being adjusted per the measured power (or the fundamental current for Class-C) while
others used some average power level to set the limits. The latter systems determine this average
power/current using some arbitrary method, and pre-test period. Thus different test systems
implement different limits for the same (fluctuating power) products, which can result in one
system PASSING a product while the other REJECTS it.
A second issue for fluctuating loads is the way the existing standard (1998 edition) defines criteria
for passing and failing the harmonics test. The existing standard permits the unit under test to
occasionally exceed the 100 % limit, provided the harmonics never exceed 150 % of the limit. In
fact, the unit under test is allowed to exceed the 100 % level for 10 % of the test time. The test
time for fluctuating loads is to be at least 2.5 minutes, i.e. the harmonics can exceed the 100 %
limit for 15 seconds in every 150-second (2.5 min) period. For longer test times, one can perform
this test in 2.5 minutes “time blocks” but another interpretation is to just take 10 % of the overall
test time. Thus, the testing method for fluctuating loads was somewhat subject to interpretation by
the test equipment manufacturer.