Abstract :
Aging of polymeric and composite materials is reviewed mainly from the standpoint of their interfacial performance. Insulating materials can be divided into simple polymers and composites. Polymers for power cables, transformers, insulators and rotating machines consist of thermoplastics such as PE, PET and PPS, elastomers such as silicone, EPR and EPDM, and thermosets such as epoxy. Composites for GIS, rotating machines and insulators comprise epoxy/glass, epoxy/silica/alumina, and epoxy/mica systems. Aging processes are complicated in general, and take place under simultaneous multiple stresses such as electrical, thermal, mechanical and environmental stresses. Some of the phenomena covered in this paper are associated with the degradation by tracking and erosion and the loss of hydrophobicity in case of surface properties, and with PD, electrical treeing, water treeing and combined phenomena. The quality of cable insulation such as XLPE has been improved extensively from the standpoint of design electric strength. Interfacial problems will emerge for modification of cable joints. It is expected that polymers for outdoor use and filled epoxy resin systems should be improved from their environmental stability and from their design stress enhancement, respectively.
Keywords :
ageing; composite insulating materials; insulation testing; organic insulating materials; polymers; EPDM; EPR; PE; PET; PPS; XLPE; aging; cable insulation; cable joints; composite insulating materials; composite materials; design stress enhancement; elastomers; electric strength; electrical treeing; environmental stability; environmental stresses; epoxy; epoxy/glass system; epoxy/mica system; epoxy/silica/alumina system; erosion; ethylene propylene diene monomer; ethylene propylene rubber; filled epoxy resin systems; hydrophobicity loss; insulators; interfacial performance; outdoor use; polyethylene; polyethylene terephthalate; polymeric materials; polyphenylene sulfide; power cables; rotating machines; silicone; thermoplastics; thermosets; tracking degradation; transformers; water treeing; Aging; Cable insulation; Composite materials; Plastic insulation; Polymers; Power cables; Power transformer insulation; Rotating machines; Thermal stresses; Trees - insulation;