Summary

Dielectric liquids, in combination with solids, have been used for insulating power transformers for more than a century. While mineral oils have dominated the market, new liquids with different molecular structures are now in common use. This brochure addresses the dielectric performance of the liquids as used in a transformer - including the potential influence of solid insulation on the behaviour of prebreakdown streamers in the liquid. Topics discussed include how the chemical composition of liquids influences the streamer velocities and breakdown, and how the electric field configuration may govern breakdown modes. The aim of this brochure is to review the dielectric requirements and test standards of dielectric liquids as seen from a transformer designer, to review the behaviour of dielectric liquids under various electric stresses, and finally, to identify knowledge gaps.

Additional informations

Publication type Technical Brochures
Reference 856
Publication year 2021
Publisher CIGRE
Study committees Materials and emerging test techniques (D1)
Working groups WG D1.70 TF3
File size 11 MB
Pages number 130
Price for non member 240 €
Price for member Free

Authors

LILJEGREN, Fijalkowski

Keywords

materials, emerging test techniques

Dielectric performance of insulating liquids for transformers
Dielectric performance of insulating liquids for transformers