Very fast transient overvoltage (VFTO) will be generated during the operation of the disconnector in GIS due to the repeated breakdown across open contacts. The high amplitude and steep wave front of VFTO seriously threaten the electrical primary insulation and cause electromagnetic interference problems. At present

in addition to using the disconnector with switching resistor to suppress VFTO in practical projects

the magnetic ring damping bus can also be used to suppress the VFTO. For assuring reliability of GIS

the suppression performance of the magnetic ring damping bus is very important. Therefore

it is urgent to research and propose a method for evaluating the magnetic ring suppression effect in the laboratory. In this paper

a special suppression performance test circuit is designed for the suppression performance of the magnetic ring damping bus

which mainly includes bushing

damping resistor

discharge gap

magnetic ring damping bus

GIS short busbar

VFTO sensor and VFTO measurement system. The rated voltage of the test circuit is 1 100 kV

the rated power frequency voltage that the bushing and busbar in the circuit can withstand is 1 100 kV

the resistance value of the damping resistor is 560 Ω or 1 500 Ω

and the discharge gap can be adjusted by the electrode spacing to generate different levels of discharge voltage and discharge steep wave

and the steep wave rise time can reach 30 ns. The test circuit is used to test the suppression effect of the magnetic ring damping busbar in the laboratory. The test results show that the test circuit can complete the test of the suppression effect of the magnetic ring damping busbar

and can quantitatively give the effect of the suppression effect. The method can be promoted to GIS products of other voltage levels

and can help to promote the realization of industrialized design

manufacture and inspection of magnetic ring damping busbar.