FE（finite element）equation of the electric field in axial symmetrical structure with suspending electrode has been derived

and the FEM（finite element method）program has been finished based on Fortran. Finally

the FEM program has been used for analyzing the electric field distribution of the SF6 terminations with and without the suspending electrode

and a comparison has been presented. The results revealed that a uniform electric field distribution is achievable

partial discharge is avoided in exterior of the terminations

and the reliability of the terminations is improved by using suspending electrode in terminations. These SF6 terminations have been performed lightning impulse voltage both positive and negative polarity 1 675 kV

15 times

under 0.3 MPa relative gas pressure.And 3 times insulation failure occurred on terminations without suspending electrodes. These test results reveal that the dielectric margin of terminations employing suspending electrodes is enhanced.