Development and Implementation of test cells to perform DC and LI breakdown testing of materials used in HVDC cable accessories
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Electric power engineering (MPEPO), MSc
Publicerad
2025
Författare
Selvasekar , Nehru Selvan
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
Abstract
The thesis work is to develop,build up and verify a test circuit for measurements of DC breakdown strength and LI testing. The work contains both practical and theoretical elements, focusing on optimizing the design of electrodes as well as the size and shape of samples and to determine the Optimal dielectric properties of the insulation test medium using COMSOL Multiphysics. The aim of the work is to develop methods and design test setups for measuring both DC breakdown strength and Lightning Impulse testing, as a function of electric fields. EPDM insulation and FGM are used in cable accessories considering EPDM rubber has low dielectric loss, making it ideal for high-voltage applications. FGM rubber can be produced by incorporating specific fillers and is designed to control and distribute electric fields within electrical insulation systems. Its main purpose is to prevent high electric field concentration, which can cause insulation breakdown and device failure.Rubber material is being tested using mechanical, chemical, and electrical methods. The dielectric test is one of the electrical testing methods used to determine the dielectric strength of rubber materials. Short-time and long-time tests are being carried out for dielectric testing. AC breakdown testing, DC breakdown testing, and LI breakdown testing on insulation EPDM and FGM samples are conducted using two different insulating liquids with variable permittivities to avoid surface flashover during a short test under international standards. Designing a test cell for a dielectric test with an applied voltage of up to 150kV. Design the test cell (CAD model) and choose the electric field simulation with COMSOL Multiphysics software. To enhance development, the molded electrode test setup has been designed to eliminate the influence of the surrounding medium and facilitate future endurance testing.
Beskrivning
Ämne/nyckelord
Keywords: NKT, Cable accessories, AC breakdown testing, DC breakdown testing, LI breakdown testing, Mineral oil, Silicone oil, EPDM, FGM, COMSOL Multiphysics.