Page 40 - Power Quality in Electrical Systems

Power-Quality Standards 23

120
EN55022A QP
EN55022A AVG Pl-1623-111695
100
EN55022B QP
EN55022B AVG
Amplitude (dBµV) 60
80

40

20

0
0.01 0.1 1 10 100
Frequency (MHz)
Figure 2.12 EN55022 conducted EMI limits [2.9].
[© 1996, Power Integrations, reprinted with permission]

One widely used standard in the European Community (EC) is the
EN55022 standard [2.12] (Figure 2.12), which is based on the require-
ments set forth by CISPR [2.13] and covers the frequency range from
150 kHz to 30 MHz.
Other agencies such as the German VDE in document VDE 0871
set requirements for the German market. When applying high-
frequency switching supplies, one must be mindful of the various
limits set forth by the regulating agencies [2.14 and 2.15]. For a power
supply to comply with these limits, the peak of the spectral lines
must fall below specified limits. In addition to conducted EMI, CISPR
and the FCC mandate limits on the radiated noise emitted from power
supplies as well.

Summary

Power-quality standards address limits to harmonics and power-quality
events at the point of common coupling in power systems. In this chap-
ter, we have covered standards addressing 60-Hz harmonics (most
notably, IEEE Std. 519 and 1159) as well as high-frequency standards
that address harmonics created by high-frequency switching power sup-
plies. Other standards, such as the CBEMA and ITIC curves set accept-
able limits for sag and swell durations for computers and other
information technology equipment.