Insulation condition assessment of medium voltage power cables using on-site PD detection and analysis techniques

Author(s):  
E. Gulski
2017 ◽  
Vol 66 (3) ◽  
pp. 475-484 ◽  
Author(s):  
Xiaokai Meng ◽  
Zhiqiang Wang ◽  
Guofeng Li

AbstractThe lifetime of ethylene propylene rubber (EPR) insulated cables will decrease because of complex aging processes. From the safety perspective, insulation condition assessment of the cable is essential to maintain an efficient and reliable operation. As a nondestructive and online evaluation method, a hardness retention rate was used to estimate the lifetime of cable. First, accelerated thermal aging tests in the laboratory were performed to measure the elongation at break retention rate (EAB%) and a hardness retention rate at different temperatures. Second, the aging values were processed by the Arrhenius equation and time temperature superposition to assess aging lifetime of insulation at different temperatures and end levels. As the insulation condition assessment of the cable by hardness retention test has no approved standard, the EAB% data were correlated with hardness retention to provide an evaluation basis. The results show that when EAB% picks out the time corresponding to a certain amount of 50% degradation, 10% of hardness retention was chosen as the termination index.


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4164
Author(s):  
Tomasz Szczegielniak ◽  
Dariusz Kusiak ◽  
Paweł Jabłoński

The use of high voltage power cables in distribution and transmission networks is still increasing. As a result, the research on the electrical performance of cable lines is still up to date. In the paper, an analytical method of determining the power losses and the temperature distribution in the medium voltage cable was proposed. The main feature of the method is direct including the skin and proximity effects. Then the Joule law is used to express the power losses in the conductor and screen, and the Fourier-Kirchhoff equation is applied to find out the temperature distribution in the cable. The research was focused on a cable with isolated screen and return current in the screen taken into account. The proposed method was tested by using the commercial COMSOL software(5.6/COMSOL AB, Stockholm, Sweden) as well as by carrying out laboratory measurements. Furthermore, the results obtained via the proposed method were compared with those given in literature. The differences between the temperature values calculated by the analytical method, numerical computations and obtained experimentally do not exceed 10%. The proposed analytical method is suitable in prediction the temperature of the power cables with good accuracy.


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