Polymeric material draws a great attraction in the development of insulation for High Votage Direct Current (HVDC) applications. Insulation material is the deciding key factor to increase the operating voltage and to transmit the bulk power with minimized power loss. Premature breakdown, high withstanding temperature, and impacts of space charge accumulation are all issues faced by the insulation material. Material qualities such as dielectric, electrical, structural, and mechanical properties are directly affected by the issues. Therefore, this paper provides an overview of the dielectric properties of polymeric materials and their composites under various stress conditions. The stress includes AC, DC, superimpose and combined (AC and DC) stress under which the dielectric constant, dielectric losses, electrical strength, and space charge distribution of polymeric insulating materials such as low‐density polyethylene, high‐density polyethylene, cross‐linked polyethylene, polypropylene, and random copolymer (RCP), as well as their composites, are explored. Polypropylene and RCP outperform all other polymers in terms of breakdown strength and space charge suppression under various stress conditions. RCP is a developing material that also has the potential to be an effective thermoplastic insulation material in the future.

Polymeric insulation for HVDC cable is attracting more attention in the modern power transmission system. Especially, the thermoplastic material is desirable for power cable insulation because of its recyclability and ease of processing. Thermoplastic material development is a good alternative to cross-linked polyethylene in the future. Polypropylene has the advantage of avoiding by-products during cable production, which can minimize space accumulation and degassing costs. Therefore, this study investigates the influence of nanofillers on the structural properties of isotactic polypropylene. In addition, the proposed composite material’s morphology, melting, dielectric permittivity, and breakdown strength are examined. Different weight percentages of inorganic nanofillers such as TiO2 and ZnO are used to make nanocomposite thin films. With increasing filler concentration, the dielectric constant of the nanocomposite thin film increases. Apart from that, the dielectric loss of the TiO2 nanocomposite thin film increases with weight percentage initially and it falls nearer to virgin material at a higher frequency. The breakdown strength of the nanocomposite materials shows a similar variation with filler concentration. TiO2 is more resistant to deterioration than ZnO composite. Based on the results of the complete investigation, the TiO2 nanocomposite is better suited for the insulation of HVDC cables.