| 1. |
- Lundmark, Martin, et al.
(författare)
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Increased levels of electrical fields in buildings
- 2002
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Ingår i: Biological effects of EMFs : proceedings, Rhodes, Greece, 7 - 11 October 2002 : [International Workshop on Biological Effects of Electromagnetic Fields]. - Rhodes : University of Ioannina. - 960-867333-X
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Annan publikation (populärvet., debatt m.m.)abstract
- In order to save energy and improve the performance, various electrical apparatus are equipped with power electronics. Normally power electronic equipment produce harmonics and high frequency noise. To handle noise emission, power electronic equipment uses EMC filters and are tested according to EMC standards. But the question is whether these tests are enough to avoid noise emissions in buildings? It has been shown, that electrical equipment distributes electrical fields inside a building using the PE wire. In order to avoid or limit electrical field it is necessary to find the sources and stop the distribution. The levels of electrical fields in the frequency range between 10 kHz and 30 MHz in office buildings and homes are rather unknown. One reason is lack of civil standards, another is lack of and difficulties in measurements. In this paper results from measurements of electrical fields in the frequency range between 10 kHz and 30 MHz at different locations is shown. An interesting result from these measurements is that the level of the electrical fields from a HF-fittings are approximately 10 times the level from video display units (VDU). This paper also shows a method to analyze sources of electrical fields.
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| 2. |
- Lundmark, Martin, et al.
(författare)
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The use of protective earth as a distributor of fields and radiation
- 2000
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Ingår i: Biological effects of EMFs : [Millennium International Workshop on Biological Effects of Electromagnetic Fields] ; Heraklio, Crete, Greece, 17 - 20 October 2000 ; proceedings. - Heraklio : Workshop on Biological Effects of Electromagnetic Fields. - 960-867330-5
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Annan publikation (populärvet., debatt m.m.)abstract
- Apart from being a safety arrangement, the protective earth, PE, is also defined as an equipotential plane which serves as a reference voltage for a circuit. Interest in the PE for EMC reasons is focused on an equipotential point. Still, most PE installation on site is carried out as a safety arrangement. In order to fulfill EMC standards regarding low emission, equipment is shielded and the shield is connected to the PE wire. The purpose of this paper is to show that electrical equipment distributes its electrical fields using the PE wire. Measurements have been taken on light fittings.
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| 3. |
- Andersson, Marcus, et al.
(författare)
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Interfering signals and attenuation potential problems with communication via the power grid
- 2006
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Ingår i: Proceedings of Nordic Distribution and Asset Management Conference : NORDAC 2006.
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Annan publikation (populärvet., debatt m.m.)abstract
- This paper will give a general overview of the potential problems associated with remote-meter reading via the power grid and describe some of the technologies available. A comparison will be made between the power grid as a communication channel and other, dedicated and shared, channels. Examples will be given of practical cases in which the communication channel does not function in the intended way.
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| 4. |
- Bollen, Math, et al.
(författare)
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Harmonic emission from installations with energy-efficient lighting
- 2011
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Ingår i: Proceeding of the International Conference on Electrical Power Quality and Utilisation, EPQU. - Piscataway, NJ : IEEE. - 978-146730379-8 ; 797-802
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Annan publikation (populärvet., debatt m.m.)abstract
- This paper presents the results from a number of measurements of the harmonic emission from installations that contain a large number of energy-efficient lamps. Two of the measurements concern the replacement of incandescent lamps with CFL and LED; the other measurement concerns an installation with up to 48 fluorescent lamps with high-frequency ballasts. The paper also contains a discussion on why the (total) power factor is not a good measure to quantify the performance of lamps or installations containing large numbers of lamps
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| 5. |
- Bollen, Math, et al.
(författare)
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Limits for voltage distortion in the frequency range 2 to 9 kHz
- 2008
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Ingår i: I E E E Transactions on Power Delivery. - I E E E. - 0885-8977. ; 23:3
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- This paper addresses voltage distortion in the frequency range 2 to 9 kHz, above what is normally considered in harmonic studies. By extrapolating the voltage-distortion limits that exist in international standards for distortion up to 2 kHz, it is concluded that 0.5% of nominal voltage per 200-Hz band is a safe limit. This limit is next used to estimate the number of small generator units (1-10 kW) that can be connected to a low-voltage grid. It is concluded that in some cases the connection of one or just a few units already leads to a distortion level above the limit.
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| 6. |
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| 7. |
- Gil-de-Castro, A., et al.
(författare)
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LED street lighting a power quality comparison among street light technologies
- 2013
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Ingår i: Lighting Research and Technology. - Sage Science Press (UK). - 1477-1535.
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Tidskriftsartikel (övrigt vetenskapligt)abstract
- High-pressure sodium lamps are currently the main lamps used in public lighting. However, the possibility of using high-power light emitting diode (LEDs) for street lighting is growing continuously due to their greater energy efficiency, robustness, long life and light control. The aim of this paper is to study the power quality of high-power lighting networks based on LED and high-pressure sodium lamps. Both electromagnetic and dimmable electronic ballasts, which can dim the lamp output smoothly and uniformly, have been used connected to high-pressure sodium lamps. High-pressure sodium lamps connected to electronic equipment have been tested with different arc power levels using dimming on a 230 V power supply. The study presented in this paper is completely based on measurements, including harmonic currents in the frequency range up to 150 kHz for all the technologies. The main results show a broadband spectrum in LED lamps which confirms other research in fluorescent lamps powered by high-frequency ballasts. Results also indicate a decrease in the harmonic value with increasing harmonic order, and a decrease in the harmonic value at half load (60%) compared with full load (100%). Although total harmonic distortion of the current is lower with high-pressure sodium lamps connected to electronic rather than electromagnetic ballasts, LED lamps achieved the lowest total harmonic distortion of curren
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| 8. |
- Lundmark, Martin, et al.
(författare)
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EMC filter common mode resonance
- 2009
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Ingår i: 2009 IEEE Bucharest PowerTech : Bucharest, Romania, 28 June - 2 July 2009. - Piscataway, NJ : IEEE. - 978-1-424-42234-0 ; 2312-2317
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Annan publikation (populärvet., debatt m.m.)abstract
- This paper discusses the possibility that high common mode voltages occur in low-voltage distribution due to oscillations between parallel connected EMC-filters. It is shown that such oscillations may occur in the frequency range between 2 kHz to 150 kHz. Simulations and measurements have been carried out with different types of parallel connected power inlet filter, a common EMC Filter, and the circumstances giving oscillations have been highlighted.
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| 9. |
- Lundmark, Martin, et al.
(författare)
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Förstudie gällande förekomst av elektriska fält i kontorsmiljöer inom frekvensområdet 10kHz - 30MHz
- 2002
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Rapport (övrigt vetenskapligt)abstract
- Projektet EMC on SITE i Skellefteå har av SIF erhållit ett uppdrag att undersöka nuläget gällande förekomst av elektriska fält i kontorsmiljöer inom frekvensområdet 10 kHz - 30 MHz. Mätningarna utfördes under senvåren - sommaren 2001. En mycket intressant iakttagelse är, i de fall belysningen består av lysrör med högfrekvensdrift (HF-drift), att det elektriska fältets styrka till största delen bestäms av belysningen, och inte av bildskärmar. Vid lysrörsanläggningar med konventionell drift (med reaktor som förkopplingsdon) var nivåerna typiskt lägre än nivån från de bildskärmar som förekom på mätplatsen. De typiska nivåerna från lysrör med HF-drift var tio ggr starkare än de från de katodstrålerörbaserade bildskärmar som fanns på mätplatserna. En annan mycket intressant iakttagelse är att bakgrundsfältet (det elektriska fältet som kvarstår när olika källor som belysning och bildskärmar slagits av), har en sådan karaktär att skyddsjordsystemet kan ha distribuerat signaler från jordade apparater i andra rumi byggnaden, till det rum där mätning skedde. I projektet har vi tidigare visat att på det sätt som skyddsjordning är utfört i våra byggnader, så kan elektriska fält av nätfrekvens (50Hz) i de flesta fall hanteras via anslutning till skyddsjord. Konsekvensen av att använda skyddsledaren för att eliminera elektriska fält för högre frekvenser, kan dock i många fall vara att den totala nivån av det elektriska fältet i byggnaden ökar. Höga nivåer av elektriska fält i luft eller höga nivåer av högfrekvent brus i våra ledningssystem (kraftnät, datanät mm.), kan allvarligt störa tekniska funktioner eller t.o.m. förstöra dem. Om vi med trovärdighet skall fortsätta med att testa och godkänna bildskärmar gällande elektriska fält, så måste de i detta fall förhållandevis höga nivåerna från lysrör med HF-drift uppmärksammas och hanteras på ett bättre sätt. Inte minst därför att ljuskällor förekommer i alla typer av lokaler, i ett betydligt större antal än bildskärmar totalt sett, samt att ökningstakten för HF-driftär mycket stor.
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| 10. |
- Lundmark, Martin, et al.
(författare)
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Harmonics and high-frequency emission by small end-user equipment
- 2006
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Ingår i: International Conference on Harmonics and Quality of Power. ; :12
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Konferensbidrag (övrigt vetenskapligt)abstract
- This paper discusses different treatments of harmonics in three phase systems, especially passive and active power factor correction (PFC). The change from harmonics below 2 kHz to above 2 kHz is described. Measurements have been carried out with two types of computer load together with LCD and florescent light driven by electronic ballast: on a large number of devices during a LAN party and on individual devices in the laboratory. Also some aspects of increasing numbers of equipment are illustrated.
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