Conductance And Space Charge Characteristics Of Polyethylene Insulation Materials

Polyethylene is a kind of thermoplastic resin obtained by polymerization of ethylene.Due to its own chemical structure,it is one of the most widely used insulating materials in the fields of high voltage transmission and electrical equipment.When a voltage is applied across the dielectric material,the electrical conductivity of the dielectric material increases,and space charge is likely to accumulate inside the polyethylene,causing electric field distortion.These factors will accelerate the degradation of insulation and greatly reduce its service life.Therefore,it is necessary to conduct in-depth research on the conductance and space charge characteristics of polyethylene insulation materials.This paper mainly discusses the conductance and space charge characteristics of polyethylene insulation under different conditions.It includes the mechanism of the ohmic characteristic region and the space charge-limited current region of the carrier under different experimental conditions.The change relationship of the electrical conductivity is studied and analyzed by changing the experimental temperature,field strength,and different metal electrodes.Calculate and analyze some parameters of the space charge-limited current region,such as carrier mobility,work function,material affinity,and so on.In addition,the analysis of the space charge problem under different metal electrode conditions was carried out.It is found through experiments that the turning point of the ohmic conducting region to the space charge limiting current region at about room temperature is about 13kV/mm.Changing the temperature of the experiment will make the turning point smaller,and it is found that changing the different temperature will only change the conductance of the ohmic conducting region.The magnitude of the current does not change its ohmic properties.According to the research and analysis of the electric conduction current at different temperatures,the relationship between the electric charge current and the Schottky emission formula can be well described in the low field,but the motor current limiting mechanism is described in the high field.Better,the temperature is better when the temperature is lower.When the temperature rises,the temperature and field strength will make the ratio of free carrier concentration in the polyethylene to the total internal carrier concentration change more than when the temperature is low.It will be different under different field strengths.Through experiments of electric conduction current and space charge under different metal electrode conditions,it is found that the amount of electrons emitted by the metal electrode changes due to the difference in the work function of the metal,thereby changing the size of the electric conduction current,and the electric conduction flow with large work function is small.The difference between the metal electrodes and the polarity of the electrodes will affect the peak of the space charge.The metal electrode has a large work function and is easy to inject holes.The work function is small and easy to inject electrons.The cathode copper anode aluminum has a spatial peak value smaller.