PURPOSE: To suppress deformation by suspending an upper module group from above a valve hole for housing a thyristor valve and installing a lower module group on the floor thereby distributing the load.

CONSTITUTION: A plurality of modules (ML) 1 are installed in layer while being spaced apart constantly by means of dielectric supporting members. The plurality of modules ML1 are classified into two groups and the upper ML group 10 is set in layer using supporting rods 2 and suspended from the ceiling part 5 of a valve hole using suspension members 4. The lower ML group 11 is set in layer using supporting posts 3 and installed on the floor 6. With regard to the upper ML group 10, the supporting rods 2 and the suspension members 4 support the weight of the ML group 11 itself without restricting the moment due to horizontal movement of the ML group 10. Consequently, the upper ML group 10 constitutes a pendulum vibration system and strong vibration is not excited.