In this paper, a kind of implantble passive wireless surface acoustic wave (SAW) sensor and its reader are developed to measure the operation temperature of high voltage crossed-linked cable core. A small type SAW temperature sensor is embedded into cable intermediate joint. A radio frequecny transceiver of the reader based on discrete devices is optimally designed to achieve high signal-to-noise ratio and receiving sensitivity. The characteristic of resonant frequency and temperature of SAW sensor is determined by frequency scan method. Through AC withstand voltage and temperature rise test of 110kV cable, it proves that the prototype can accurately measure the operation temperature of 110kV cable core in intermediate joint under high operation temperature and strong electromagnetic environment.

Space charge dynamics under sinusoidal voltages are calculated based on bipolar charge transport model. The effects of AC voltage amplitude and frequency on current densities, electroluminescence intensities and space charge densities are investigated. It is shown that the carrier densities increase with the increase of AC voltage amplitude, but the thickness of the space charge layer approximately unchanged. The frequency of AC voltage has no effects on space charge dynamics when the frequency reaches the order of ten.

When the cables are laid with equal spacing, its ampacity is limited due to the mutual heat effects. In order to increase the ampacity of the cable group, an optimum laying method with unequal spacing is proposed in this paper. The constraint function is that the temperature of all cables is lower than the upper limit, and the objective function is that the ampacity of cables is maximum. The constrained problem is transformed to an unconstrained problem by constructing a penalty function. The results show the effectiveness of the proposed method. The ratio of the increased ampacity increases with the increase of cable numbers.