Emission by modern energy-efficient equipment and possible impact on communication

Content: Distortion at electronic loads Measuring technology from 2 to 150 kHz Analyzing techniques Measurements of light equipment Trends of harmonics and power consumption at LAN-parties 2002-2008

Remains from switching Scheme of SMPS for power conditioning

Diversity of current drawn by electronic loads Examples of small electronic devices containing power electronics (plus an incandescent lamp).

Fig. 2.3 Harmonic spectrum of the current waveforms shown in Fig. 2.2.

Diversity of current drawn by similar electronic loads Current drawn by 6 different ballast powering 2x49 W tubes

Measuring technology 2 to 150 kHz

Standards covering different frequency range Harmonic range (up to 2 kHz) is covered by IEC 61000-4-7, IEC 61000-4-30, IEC 61000-3-2 2 to 9 kHz is covered by IEC 61000-4-7, Annex B 9 kHz and up is covered by CISPR 16

Some features of IEC 6100-4-7 Annex B (2 to 9 kHz) Prescribes time domain based measurements A band-pass filter is prescribed between 2 to 9 kHz. The attenuation below 2 kHz is used to damp the fundamental > 560 times (55 dB). The attenuation above 9 kHz is used to avoid anti-aliasing. This can be skipped if the dynamic range of the instrument is large enough The sampling frequency should be chosen in accordance with the established rules of signal analysis A 200 ms rectangular window of the signal should be taken, not necessary synchronized with the fundamental

Some features of IEC 6100-4-7 Annex B (2 to 9 kHz) A DFT should be used resulting in 5 Hz frequency separation. These frequency components, Yc,f, should be grouped into 200 Hz band according to: This to comply with CISPR band A between 9 and 150 kHz.

Some features of CISPR 16 (9 to 150 kHz A-band) Prescribes measurements of the frequency domain using measuring receivers The resolution bandwidth should be 200 Hz Different types of detectors is prescribed QP, RMS, Peak, Average

Different types of instrument to use for this frequency range

Measurement at lower frequencies PQ instruments

Measurements at higher frequencies Measuring receivers

Oscilloscopes

Memory recorders

Analyzing technology

Ex. signal

Resulting DFT

Short Time Fourier Transform (STFT)

Short Time Fourier Transform (STFT)

Time-frequency separation

Ex. Measurement on fluorescent lamp

0 to 48 lamps project

Measurement setup Individual lamp current is also measured Itot and U is measured

Resulting voltage spectrums 51 kHz 28 kHz

Resulting total current spectrums

Resulting lamp current spectrums

Circuit theory model of the remnants of the lamps

, IL1 and IL2 in phase IL1 and IL2 in opposite phase Iem Vem

, IL>2 in phase and opposite phase to IL1 All IL in phase Iem Vem

Measured result from the “0 to 48 lamp project”

Trends of harmonics and power consumption at LAN-parties 2002-2009

Mean power per computer in Watt

Relative neutral current magnitude

3rd, 5th and 7th harmonics over the years

Conclusion Different types of electronic loads shows diverse frequency spectrums, both in harmonic range and in the higher frequency range. Also same type of equipment shows differences Measurements using time-domain sampling instrument is useful. It is more flexible to use and provides the opportunity to use different types of analyzing methods In the frequency range above 2 kHz the STFT has been shown as a useful analyzing tool to achieve information about signals Cont->

Distortion generated at HF-ballast equipped with active PFC can be categorized into, narrow- and broadband- distortion. Also these ballast creates recurrent oscillations close to the zero-crossing The distortion from switching seems to stay within the groups of lamps instead of traveling towards the transformer Conclusion of measurement on LAN-parties Between 2002 and 2009 is: no change in current amplitude no change in power consumption large reduction in harmonic distortion