PURPOSE: To facilitate attaching and detaching of a tray for a water cooling thyristor and distributing water pipes and to contrive to enhance efficiency of work of maintenance and inspection thereof by a method wherein one-touch way attaching and detaching connectors are used to connect the tray module and the distributing water pipes.

CONSTITUTION: Male parts of the connectors 14 are fitted up to a fixed panel 22, and female parts thereof are fitted up to the tray 12. Wheels 24 of the tray are put on rails 26 of the panel, and guides 28 of the tray facilitate going in and out of the tray. A stopper 32 of the tray is caught by a B-shaped receiver 30 of the panel, and are connected electrically by plug receptacles 34 of the panel and plugs 36 of the tray. The outside of the connectors 14 of the panel are connected to the distributing water pipes 16A, 16B through branch pipes, and cooling water 40 is supplied to the tray to perform cooling. When the connectors 14 are disconnected, movable pieces of both the male and the female sides act to block the water pathes, and when they are inserted, the pathes are connected. By this constitution, the tray 12 can be taken in and out from the fixed panel 22 easily using the connectors 14 attachable and detachable freely, and maintenance and inspection work is facilitated.