Capacitive reactive power is generated in the transmission line and cable in power supply network during operation.Since the distribution network of urban network modification is mainly composed of high voltage cables

in which the capacitive reactive power generated has a serious impact on the safe and economic operation of distribution network.For solving the over compensation issue of capacitive reactive power of power system

the analysis is made from the generation mechanism of the capacitive reactive power in the power system

the features of such reactive power of power system and solution are found.It is shown by the result that the capacitive reactive power in the power system is determined by the structure and length of transmission line and cable of the power network.Once the network structure is determined

its capacity is relatively fixed with less variation.Therefore

the compensation to capacitive reactive power of power system shall be relatively fixed and such principle as spread and concentrated compensation is adopted for disposition.As for reduction of operation reliability due to capacity increase of arc supersession coil because of the increase of earthed capacitive current in the small current earthing system at 10 kV and 35 kV

the extinction device named Y connection with both functions of inductive compensation and reduction of earthed capacitive current is developed its principle and performance are introduced.