Electrical Breakdown Mechanism of ENB-EPDM Cable Insulation Based on Density Functional Theory

Area of Science:

• Materials Science
• Electrical Engineering
• Computational Chemistry

Background:

• Ethylene propylene diene monomer (EPDM) is crucial for high voltage direct current (HVDC) cable accessories due to its excellent insulation.
• Understanding EPDM's behavior under intense electric fields is vital for ensuring the reliability of HVDC systems.

Purpose of the Study:

• To investigate the microscopic reactions and space charge characteristics of EPDM under varying electric field intensities using computational methods.
• To elucidate the impact of electric fields on EPDM's molecular structure, stability, and electrical properties.

Main Methods:

• Density functional theory (DFT) was employed to simulate EPDM's response to electric fields.
• Analysis included changes in total energy, dipole moment, polarizability, molecular geometry, and electronic band structure.

Main Results:

• Increasing electric field intensity decreased EPDM's total energy and stability, while increasing its dipole moment and polarizability.
• Molecular chain elongation and decreased structural stability led to diminished mechanical and electrical properties.
• Conductivity improved as the energy gap decreased, with shifts in active sites causing varied charge trapping.

Conclusions:

• EPDM's molecular structure is compromised and eventually destroyed at high electric field intensities (0.0255 a.u.), evidenced by significant spectral changes.
• These findings offer a theoretical foundation for developing improved EPDM modification technologies and support high voltage experimental research.