Abstract
The Joule heat produced by the current in conductor decreases in the radial direction, producing a temperature gradient in the insulation. This existing temperature gradient can affect the electrical tree phenomenon in insulation materials because of the temperature dependence of insulation material, charge migration and tree growth. Different temperature gradients were obtained by controlling the temperature of high voltage (HV) and ground electrode (GD) sides. The electrical tree was recorded by a microscope, while the partial discharge (PD) was observed simultaneously. For better understanding the effects of the temperature gradient on electrical tree inception, the trap distribution in silicone rubber (SIR) with different temperature was analyzed by isothermal discharge current (IDC) method. With the fixed temperature in HV or GD side, it was found that the electrical tree inception voltage decreased linearly with increasing temperature in either side. The IDC results indicate that the increasing temperature contributes to the de-trapping of charges and lowers the inception voltage. Besides, the electrical tree length and accumulated damage gradually increase with the temperature gradient. The observed PD amplitude and quantity also increase with the temperature gradient, which facilitates the growth of electrical trees. These results indicate that the tree growth is promoted with an increase in the temperature gradient of the cable insulation, posing a threat to the safety of the cable system.
Highlights
Cable accessories are the weak points in cable operation because of the nonuniform electric field distribution caused by their multilayer insulation structure [1], [2]
The electrical tree inception is related to the electron injection-extraction process and charge transport [21], [22], and the growth characteristics are determined by partial discharge (PD) and space charge accumulation [23], [24]
The trap distribution was tested at different temperatures
Summary
Cable accessories are the weak points in cable operation because of the nonuniform electric field distribution caused by their multilayer insulation structure [1], [2]. The temperature gradient is formed by Joule heating due to the inner current during the cable operation, which will change the electrical properties of SIR in the radial direction [7]–[9]. It is known that the temperature will affect both the electrical tree inception and growth processes [16]–[20]. The electrical tree inception is related to the electron injection-extraction process and charge transport [21], [22], and the growth characteristics are determined by partial discharge (PD) and space charge accumulation [23], [24]. The charge behavior of insulation makes the distortion of the electric field inside cable accessories more severe, readily leading to insulation degradation [17], [23], [25]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
