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Lars Lundgaard

Chief Scientist

Lars Lundgaard

Chief Scientist

Lars Lundgaard
Phone: 930 07 018
Department: Electric Power Technology
Office: Trondheim

Publications and responsibilities

Publication
https://www.sintef.no/en/publications/publication/?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 ...

Authors Linhjell Dag Lundgaard Lars Esben Unge Mikael
Year 2019
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?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...

Authors Liland Knut Brede Linhjell Dag Lesaint Cedric Michel Ese Marit-Helen Glomm Lundgaard Lars Esben Mavrommatis Pascal Stjepanovic Nenad Miroljub
Year 2017
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?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 ...

Authors Aakre Torstein Grav Lundgaard Lars Esben Unge Mikael
Year 2017
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?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...

Year 2017
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1526026

Third mode streamers have been studied in the mineral oil Nytro 10 XN, gas-to-liquid oil Diala S4 ZX-1 and the high viscosity white oil Primol 352, in an 80 mm point-plane gap under step impulse voltage. Third mode streamer velocities were in the range 4–60 km/s. The "acceleration" of the ...

Authors Linhjell Dag Lundgaard Lars Esben Unge Mikael
Year 2017
Type Part of a book/report
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1385663

For introducing power converters at ambient pressure at large sea depths, dielectric liquids are proposed as insulation for power electronic converters. This paper presents statistical analysis of short time tests of partial discharge and breakdown voltage on the trench between metallized edges of p...

Authors Abdelmalik Abdelghaffar Amoka Borge Malin Drevdal Nysveen Arne Lundgaard Lars Esben Linhjell Dag
Year 2016
Type Journal publication
Publication
https://www.sintef.no/en/publications/publication/?pubid=CRIStin+1385622

To facilitate operation of power electronics for subsea operation at ambient pressure components have to be submerged in a liquid. Equipment and schemes for testing of long term properties have been developed. Several techniques were used to investigate compatibility between a silicone gel and vario...

Year 2016
Type Part of a book/report