GB/T 3906-2006

This standard specifies the technical requirements for factory-assembled AC metal-enclosed switchgear and control equipment with a rated voltage of 3.6 kV to 40.5 kV, installed indoors or outdoors, and a frequency of 50 Hz or lower. The equipment may contain fixed or removable components within the enclosure and may be filled with insulating and/or interrupting fluids (liquids or gases).
Note 1: This standard is primarily intended for three-phase systems, but it can also be used for single-phase or two-phase systems. According to the following factors, this standard classifies metal-enclosed switchgear and control equipment into several categories:
-- The continuity of grid operation during the maintenance of switchgear and control equipment;
-- The need and convenience of equipment maintenance.
Note 2: The safety of the equipment depends on the design, use, adjustment, coordination, installation, and operation of the product.
For metal-enclosed switchgear and control equipment with inflatable compartments, this standard applies when the design pressure does not exceed 0.3 MPa (relative pressure).
Note 3: Inflatable compartments with a design pressure exceeding 0.3 MPa (relative pressure) should be designed and tested in accordance with GB 7674.
Metal-enclosed switchgear and control equipment for special purposes, such as those used in flammable gas environments, mines, or on ships, may require additional technical requirements.
The various components installed in metal-enclosed switchgear and control equipment should be designed and tested in accordance with the respective standards. Taking into account the installation of each component in the complete switchgear and control equipment, this standard supplements the standards for individual components.
This standard does not exclude the use of other equipment in the same enclosure, in which case the impact of the equipment on the complete switchgear and control