Development of mixed dielectrics for high voltage power capacitors using mineral oil

Development work in a dielectric system consisting of one layer of biaxially oriented polypropylene film (ppf) and kraft paper impregnated with Hydrocarbon oils has been described in detail to replace the use of PCB in power capacitors. Three sample capacitors have been tested with different percentage composition of ppf and kraft paper. Extensive theoretical and experimental work was done and it has been suggested that a combination of 65% ppf with 35% kraft paper will give an optimal design from an economical point of view. The behaviour of capacitance and tanδ with temperature, time and voltage gradient, has been explained.