The insulation fault of extra-high voltage（EHV） cross-linking polyethylene（XLPE） power cable termination has a great influence on stability of power grid

and it is very important to effectively evaluate the thermal state of EHV XLPE power cable termination for forecasting insulation fault. In order to study the evaluation method for thermal state of EHV XLPE power cable termination

we analyzed thermal distribution characteristic of EHV XLPE power cable termination surface

put forward a thermal state evaluation method on the basis of the maximum temperature difference of EHV XLPE power cable termination surface. According to the requirements of IEC 62067: 2011 and GB/T 22078—2008

we designed and performed a prequalification test of 500 kV XLPE cable system

and analyzed the thermal distribution characteristic of the EHV XLPE power cable termination surface at different ambient temperatures by method of thermal infrared imaging. The results show that environmental interference of thermal field analysis can be effectively reduced by evaluation for the maximum temperature difference of EHV XLPE power cable termination surface. If the maximum temperature difference Δθ≈1 ℃

EHV XLPE power cable termination is in good thermal state

and if the maximum temperature difference Δθ 1 ℃

EHV XLPE power cable termination is in bad thermal state. If Δθ is too large

it is suggested that EHV XLPE cable termination has an abnormal thermal state. The availability of the thermal state evaluation method for EHV XLPE power cable termination is verified by experiments.