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Lars Lundgaard

Sjefforsker

Lars Lundgaard

Sjefforsker

Lars Lundgaard
Telefon: 930 07 018
Avdeling: Elkraftteknologi
Kontorsted: Trondheim

Publikasjoner og ansvarsområder

Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1816551

The effect of pressure on positive and negative streamer propagation in a mineral transformer oil is studied in an 80 mm point-plane gap under step voltage. Increased pressure causes reduced stopping length for non-breakdown streamers, higher breakdown voltage, reduced background current, reduced br...

Forfattere Linhjell Dag Lundgaard Lars Esben Unge M. Hjortstam Olof
År 2020
Type Tidsskriftspublikasjon
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1807150

This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under negative polarity stress. Stopping length for non-breakdown streamers, breakdown voltages and velocities for various pre-breakdown streamer modes have been studied for a selection of model liquids ...

Forfattere Lundgaard Lars Esben Linhjell Dag Hestad Øystein Leif Gurandsrud Unge Michael Hjortstam Olof
År 2020
Type Tidsskriftspublikasjon
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1807148

This study addresses the dielectric performance of nonpolar hydrocarbon liquids and mineral oils under positive polarity stress. It is of interest to improve knowledge on how functional properties of dielectric liquids vary, as new brands arrive in the market, and existing standards are unsuited for...

Forfattere Linhjell Dag Lundgaard Lars Esben Unge Michael Hjortstam Olof
År 2020
Type Tidsskriftspublikasjon
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1717940

The propagation of positive streamers in a naphtenic transformer oil in an 80 mm point-plane gap has been investigated under an impulse voltage being close to a step voltage and under pressures ranging from 0.1 to 1.7 MPa. As has previously been found in short gap experiments of 1 – 7 mm in various ...

Forfattere Linhjell Dag Lundgaard Lars Esben Unge Mikael
År 2019
Type Del av bok/rapport
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1526050

For transformers in service, aging markers from cellulose in oil such as furans, water, methanol and acids are measured for diagnostic purposes. The content of these indicators, measured in oil, may therefore vary with load, temperature, solid and liquid insulation aging, as well as marker stability...

Forfattere Liland Knut Brede Linhjell Dag Lesaint Cedric Michel Ese Marit-Helen Glomm Lundgaard Lars Esben Mavrommatis Pascal Stjepanovic Nenad Miroljub
År 2017
Type Del av bok/rapport
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1526045

An automated setup for testing dielectric performance of liquids in a small point-to-plane gap is presented. It provides step voltages with rise times around 30 ns, with amplitudes up to 90 kV. Breakdown studies of thirteen different liquids were conducted with a gap distance of 4 mm in a test cell ...

Forfattere Aakre Torstein Grav Lundgaard Lars Esben Unge Mikael
År 2017
Type Del av bok/rapport
Publikasjon
https://www.sintef.no/publikasjoner/publikasjon/?pubid=CRIStin+1526028

A sensitive differential charge measurement technique was used to measure the conduction current from a sharp needle in a needle plane geometry in n-pentane. The current was measured at voltages up to the threshold for streamer inception in n-pentane with a positive needle polarity. The measured cur...

Forfattere Hestad Øystein Leif Gurandsrud Linhjell Dag Lundgaard Lars Esben Samseth Jarl Ø. Unge Mikael
År 2017
Type Del av bok/rapport