Research on the Electric Breakdown of Fully Impregnated Paper Insulation for High-Voltage Cables [includes discussion]

Research on the dielectric strength of high-voltage cables can be very conveniently carried out on "models". Either plate or cylindrical capacitors can be used for this purpose. This paper reports the results of many tests both at power frequency and at impulse, which have the purpose of investigating the separate and combined influence of a series of different factors affecting the dielectric strength of a fully impregnated paper insulation as used in high-voltage cables. The main factors investigated are the following: Paper impermeability, Paper density, Paper thickness, Oil viscosity, Oil pressure, Electrode surface shape, Electrode surface nature, Butt-space thickness, Butt-space position with respect to electrodes. Butt-space relative position. The paper ends with a comparison of results obtained on models and on actual oil-filled cables, which show a good agreement if certain assumptions are taken into consideration.