In order to clarify the relationship between electro luminescence (EL) and
degradation in crosslinked polyethylene (XLPE), the EL measurement was carr
ied out using three kinds of samples, block samples with two different elec
trode systems, and him samples. The spectral measurements revealed that the
vv component of EL is below the detectable level of similar to 0.1 c/s (co
unt per second), in contrast to partial discharge (PD) light from microvoid
s or the tiny electrical tree which includes a uv component of greater than
or similar to2 c/s. Secondly aging tests using XLPE block samples with nee
dle-plane electrodes revealed that electrical degradation can take place ev
en when the applied voltage is below the EL detection voltage. The above ex
perimental results suggest that EL is not the origin of electrical degradat
ion, i.e, photodegradation by the uv component of EL is not the dominant me
chanism of electrical degradation.