Power Cable Insulation Composition for Low Dielectric Loss
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Solution Overview
Problem
Current polymer compositions used in wire and cable applications, particularly for high voltage and extra high voltage applications, face challenges in maintaining good dielectric properties at elevated temperatures due to non-decomposed catalyst residues and lack of balance between dielectric, thermal, and mechanical properties.
Innovation Solution
A cable with a polymer composition comprising at least 75 wt % ethylene-based plastomer blended with 0.2 to 10 wt % amine or oxide filler, or a combination with 50 to 95 wt % polyolefin such as LDPE, polypropylene homopolymer, or random heterophasic polypropylene copolymer, achieving dielectric losses of 200×10−4 or less at 500V/mm and 90°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ethylene-based plastomer is used to provide softness and flexibility, then mechanical properties are improved, but dielectric properties at high temperature deteriorate due to non-decomposed catalyst residues
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the ethylene-based plastomer and the inorganic filler particles. The silane coupling agent has both organic functional groups that interact with the polymer matrix and inorganic functional groups that bond to filler surfaces, thereby improving interfacial adhesion and reducing the negative effects of catalyst residues on dielectric properties while maintaining mechanical flexibility
Solution Approach 2:
The invention creates a composite material system consisting of ethylene-based plastomer, inorganic filler particles (such as silica or alumina), and silane coupling agent. This composite structure combines the flexibility of the plastomer with the thermal stability of inorganic fillers, while the silane coupling agent ensures proper interfacial bonding, thereby achieving both good mechanical properties and improved dielectric performance at elevated temperatures
2Reliability
If catalyst residues are minimized by careful choice of metallocene activator, then dielectric properties are improved, but manufacturing cost increases
Solution Approach 1:
The silane coupling agent serves as a mediator that allows the use of more economical catalyst systems while still achieving good dielectric properties. By improving the interfacial interaction between polymer and filler, the silane coupling agent compensates for the presence of catalyst residues, enabling the use of cost-effective catalysts without sacrificing electrical performance
Solution Approach 2:
The invention changes the chemical parameters of the filler surface through silane treatment, transforming ordinary inorganic fillers into functionally enhanced fillers with improved polymer-filler interfacial adhesion. This parameter change allows the system to tolerate higher catalyst residue levels while maintaining dielectric properties, thereby reducing catalyst cost
3Reliability
If charge dissipation modifiers are added to improve dielectric performance, then dielectric properties are improved, but device complexity increases
Solution Approach 1:
The silane coupling agent performs multiple functions simultaneously: it improves interfacial adhesion between polymer and filler, modifies filler surface properties to reduce catalyst residue effects, and enhances the overall dielectric performance of the composite. This multi-functionality eliminates the need for separate charge dissipation modifiers, thereby improving dielectric properties without increasing composition complexity
Data Source
AI summary
The invention provides a cable, preferably a power cable, comprising one or more conductors surrounded by at least one layer, preferably an insulation layer, wherein said layer comprises a polymer composition comprising: (i) at least 75 wt % of an ethylene based plastomer; and (ii) 0.2 to 10 wt % of an amine filler, oxide filler or mixture thereof; and wherein said polymer composition has a dielectric loss expressed as tan δ (50 Hz) of 200×10−4 or less, when measured at 500 V/mm and 90° C. as described in the description part under “Determination methods”.