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Conductivity current is an important parameter to study the carrier transport mechanism in high voltage insulated cables. In this paper, the carrier transport mechanism in the ohmic characteristic region and space charge restricted current region of polyethylene insulation is studied by changing the experimental field strength (5kv/mm-45kv/mm), temperature (25 ℃-55 ℃) and metal electrode. It is found that the space charge limiting current effect and Schottky emission effect are close to the measured conductivity current in the low field region, and the electrode limiting current effect is very stable in the high field region. Changing the temperature will only change the conductivity current in the ohmic conductivity region. Small, does not change its ohmic characteristics. The work function of the metal electrode is equal to the electrode barrier height plus the material affinity energy. According to this relationship, the barrier heights of different metal electrodes are determined, and then the ability of different metal electrodes to emit electrons is discussed. It is found that the larger the work function of metal electrode, the smaller the conductance current in the medium. Combining the measured data with the theoretical formula, the A value of aluminum electrode is 1.51 × 105A/ (m2·k2).
Inspec keywords: Schottky barriers; electrodes; Schottky effect; current density; space-charge-limited conduction; space charge; polyethylene insulation; ohmic contacts; electric fields; aluminium; work function; electrical conductivity
Subjects: Electrical conductivity of organic compounds and polymers; Dielectric breakdown and space-charge effects; High-field transport and nonlinear effects (semiconductors/insulators); Contact resistance, contact potential, and work functions; Electrochemistry and electrophoresis