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Electrical Integrity Tests and Analysis of Low Voltage Photovoltaic Cable Insulation under Thermal Stress

In the last decade, photovoltaic power systems have emerged as a leading source of electrical energy. Due to its outdoor installation, it is exposed to all sorts of climatic stresses, such as mechanical, ultraviolet radiation, temperature, and humidity stresses. Safe and reliable operation of the photovoltaic systems is highly dependent on the DC cables installed between the photovoltaic modules and inverters. Since these cables not only carry the load current but are also exposed to the external harsh environment and hence are more vulnerable to degradation. This research has been aimed to study the aging of low voltage photovoltaic DC cables under thermal stress. The cable samples are thermally accelerated aged and the electrical integrity of these cables are studied by the dissipation factor and capacitance measurement in the frequency range of 20 Hz to 500 kHz. The results show that because of aging the dipolar polarization has been affected. Also, the minimum value of the dissipation factor has significantly decreased at lower frequencies, in addition, the shifting of the minimum value of dissipation factor to lower frequency with the aging has also been observed.