SWITCHING OR OUTLET BOX, IN PARTICULAR FOR USE ON RAIL DISTRIBUTORS OF LOW VOLTAGE SWITCHGEAR

摘要

In switch or outlet boxes, as are also used on distributing busbars of low-voltage switchgear, in the case of a disturbing arc there is a risk of a sudden pressure increase within milliseconds, as a result of which the pressure-relieving flaps bulge up, which adversely affects the opening movement of the flaps to a high extent. It is thus necessary to construct the pressure relieving wall such that it reacts within a few milliseconds in order to relieve the housing space affected by it in a sudden manner from the internal pressure occurring, without the housing itself or the apparatuses located therein being damaged thereby. This is achieved in that the pressure relieving wall (4) consists of two pressure relieving flaps (9, 10), which abut approximately in the centre of the end wall of the metal housing (3) and each of which is attached by means of an attachment strip (11, 12), which is bent through 90 DEG , to the respectively adjacent housing side wall (13, 14), in that there are perforations (17, 18) as weak zones at the bending edges (15, 16) between the pressure relieving flaps (9, 10) and their attachment strips (11, 12), and in that only one (9) of the two pressure relieving flaps (9, 10) is secured by means of a retaining tongue (19) to the housing (3) of the switch or outlet box (1), while the second pressure relieving flap (10) is supported only at the edge on the first pressure relieving flap (9). IMAGE