AMETEK MX CTSL - Manual (Page 16)

User Manual MX-CTSL Compliance Test System
California Instruments Revision J 16
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 EN61000-3-2 and EN61000-3-3, which supersede
EN60555.2 and EN60555.3 respectively. These standards are also known under the IEC designator EN
61000-3-2 and EN 61000-3-3. Recently, the universal EN 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 EN 61000-3-2 and EN 61000-3-3.
2.3 The EN 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.