AMETEK CTS 3.0 - Manual (Page 28)

Compliance Test System 3.0 User Manual
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party reference impedance networks with the CTS system as the combined AC source and
network impedance may not match the IEC 61000-3-3 requirement. The 1251RP-CTS is always
supplied with a lumped reference impedance built in to the PACS-1 unit as these AC Source
models do not offer programmable output impedance.
In general, programmable output impedance of the AC Source yields higher accuracy compared
to a physical lumped impedance. It also allows testing against other national flicker standards
such as those in Japan where different reference impedance values are called out.
2.6.2 When to Test for IEC 61000-3-3
As mentioned, it may not be necessary to test every product for IEC 61000-3-3. If it can be shown
that maximum power consumption of the unit under test is low, and the surge current level at turn-
on is limited, it can be shown that the product causes insignificant Flicker levels across the
reference impedance. For loads having an rms current draw of more than 5 Amps, it is generally
recommended to verify conformance to IEC 61000-3-3 however.
2.7 IEC 61000-4-11 Voltage Dips and Variations
The IEC 61000-4-11 is an immunity test for low voltage equipment to ensure reliable operation
when connected to the public distribution system. This test requires an AC source that is capable
of generating specific voltage variations and voltage dips. The unit under test must not sustain any
damage from such occurrences nor cause unsafe conditions.
DEPTH DURATION
(Voltage drop in % of
nominal Ut)
10 to < 100 ms 100 to < 500
ms
500 ms to 1
sec
1 sec to > 3
sec
10 %o < 30 % 61 66 12 6
30 % < 60 % 8 36 4 1
60 % < 100 % 2 17 3 2
100 % 0 12 24 5
Number of disturbances per year
The need to test for immunity of products against voltage dips and interruptions was prompted by
studies of electric utility availability. The results shown in Table 2-4 were found in this study
(UNIPEDE study 91 en 50.02). From this data it is clear that most disruptions are short in nature
(about 5 to 10 periods) and no more than 60 % below nominal. Occasionally however, extended
periods of complete power loss occur. It is suggested that this test data also be used as a guide in
selecting appropriate test levels.
2.7.1 Why Do You Have to Test?
The IEC 61000-4-11 affects a large set of products, specifically; "Electrical and electronic
equipment having a rated input current not exceeding 16 A per phase." Thus, most single and
three phase AC powered equipment used in domestic and light industrial settings fall in this
category. In fact, around 95 % of all electrical equipment in household and light industrial
applications, require no more than 16 A per phase. In Europe, this implies real apparent levels of
230 V * 16 A = 3680 VA, with real power either at the same or a lower level. Specifically excluded
are all DC powered products (battery operated devices) and 400 Hz AC equipment. (Avionics)
These products will be covered in future IEC standards. At this time meeting the IEC 61000-4-11
standard is required for most products to obtain the CE Mark, required to market products in the
European Union.
Table 2-4: Average public utility disturbances per annum in Europe