1. IEEE Trial use standard general requirements and test code for oil immersed HVDC converter transformers, IEEE Std C57.129-1999, IEEE USA.
2. Recommended dielectric tests and test procedures for converter transformers and smoothing reactors;Kennedy;IEEE Trans. Power Deliv.,1986
3. Influence of carbon particle on the breakdown voltage of transformer oil;Krins,1996
4. Particle initiated breakdown in quasi uniform field in transformer oil;Carraz;IEEE Trans. Dielectr. Electr. Insul.,1995
5. Behaviour of free conducting particle and their role on breakdown in oils under AC and DC voltage;Rain,1992