The voltage sensor of high voltage arm of capacitive voltage divider

which is composed of stray capacitance between inductive electrode and high voltage conductor

is the primary measurement measures of transient voltage in GIS. However

the electric field of each phase of three-phase enclosed structure of GIS is coupled each other at the position of voltage sensor. It is therefore necessary to study the decoupling method so to accurately measure the VFTO voltage waveform of each phase. In this paper

the phase voltage measurement system of three-phase enclosed GIS busbar is set up firstly in accordance with the triangle layout characteristic of the three-phase enclosed GIS busbar and in combination with capacitive voltage division principle of voltage sensor. The electric field coupling coefficient matrix is proposed. The two-dimensional simulation model is set up by using simulation so to study the influence of the position of the voltage sensor on the electric field coupling matrix. The results show that the corresponding electric field coupling coefficient reaches the maximum when the voltage sensor is at the“close point”of the phase bus

and the electric field coupling coefficient of the other two phases is almost zero. The electric field coupling coefficient matrix is transformed into a diagonal matrix so to achieve the purpose of decoupling. Furthermore

the three-dimensional model is set up in this paper and the conclusion the two-dimensional model is verified. And such conclusion as the larger the depth of the hand hole voltage sensor is

the smaller the diameter of the hand hole is and the smaller the electric field coupling coefficient is

which provides a reference for engineering practice.