PURPOSE: To shorten mounting/dismounting time by employing curved male and female engaging sections in a contactor, a connecting conductor and an intermediate conductor for connecting insulating spacers fixed to facing flanges for mounting/dismounting a gas insulated apparatus.

CONSTITUTION: Tanks 22, 23 and a bellows 23 are fixed between insulating spacers 2 fixed to a flange 1. Contactors 24, 25 having curvature are fixed to the insulating spacer 2 in order to relieve the electrical field. Male and female plug-in type contactors 24, 25 are employed. A male connecting conductor 26 is plugged into the contactor 24 and an intermediate conductor 27 is tightened through a bolt 27 between the connecting conductor 26 and the male contactor 25. When it is dismantled, a bellows 23 is contacted and removed, then the bolt of the intermediate conductor 27 is loosesned and the connecting conductor 26 is pulled out. The tanks 22, 23 are closed with blind covers and gas insulated apparatus are charged independently with a main circuit voltage. By such arrangement, field relief shield is not required for the contactors 24, 25 and work time is shortened upon occurrence of fault.