Relation between electroluminescence and degradation in XLPE

In order to clarify the relationship between electroluminescence (EL) and degradation in crosslinked polyethylene (XLPE), the EL measurement was carried out using three kinds of samples, block samples with two different electrode systems, and film samples. The spectral measurements revealed that the UV component of EL is below the detectable level of ~0.1 c/s (count per second), in contrast to partial discharge (PD) light from microvoids or the tiny electrical tree which includes a UV component of ≳2 c/s. Secondly, aging tests using XLPE block samples with needle-plane electrodes revealed that electrical degradation can take place even when the applied voltage is below the EL detection voltage. The above experimental results suggest that EL is not the origin of electrical degradation, i.e. photodegradation by the UV component of EL is not the dominant mechanism of electrical degradation