EAM insulation for medium-volt power cable applications

Traditionally, medium-volt (MV) power cable producers had two choices for insulation. These broad categories are cross-linked polyethylene (XLPE) and ethylene-propylene rubber (EP), and include all of their variations, such as tree-resistant XLPE (TRXLPE), ethylene-propylene rubber (EPR), ethylene-propylene-diene (EPDM), etc. Over the last several years, technology has developed that has allowed polymer producers to offer a new category of material for use in electrical insulation: EAM (ethylene-alkene copolymer). These materials include components other than the traditional ethylene and propylene building blocks and offer advantages in processability, flexibility, and performance. The broad range of melt flow rates, densities, and molecular weight distributions available allows compound producers to find the right properties to balance optimal distributive mixing with extrusion performance. The biggest challenge facing EAM resins as an insulating material is acceptance by a fairly conservative industry. Cable producers must be able to take advantage of materials with improved processing as well as physical and electrical properties in the cost conscious deregulated utility industry. This work will examine the suitability of filled EAM as an insulation category, and will discuss specific types of materials that fall into that category. The paper will provide cable test data in comparison to traditional XLPE and EPDM formulations available today. Test data will include Association of Edison Illuminating Companies (AEIC) Qualification data, Accelerated Cable Life Test (ACLT) results, and ICEA testing, among others.