GB 50217-94 电力工程电缆设计规范

1. General Principles
1.0.1 This code is established to practice a technically advanced, economically rational, reliable and applicable design of cables of electric work and facilitate construction and maintenance.
1.0.2 This Code is applicable to the selections and laying design of 200kV and below 200 kV power cables and control cables used in newly built and expanded electric work.
1.0.3 The cable design for the electric work shall not only abided by this Code, but also comply with the provisions of the current relevant national design codes and standards.
2. Terminology
2.0.1 Fire Resistance
It is a characteristic property that the energization and operation of cables can be maintained by the action of flame at a specific elevated temperature for a specific time.
2.02 Flame Retardancy
It is a characteristic property of cables that cable is ignited by the action of the flame under the specific testing conditions and it will extinguish by itself as soon as the flame source is removed.
2.0.3 Dry-type Cross-linked
It is a general term for the cross-linked process used to reduce remarkably the moisture of cross-linked polyethylene insulation materials during manufacturing.
2.0.4 Water Tree
It is a brief term to describe a phenomenon of tree fine cracks in insulation layer of cross-linked polyethylene cables under operation, which results in the deterioration of insulation properties and causes the failure of cables.
2.0.5 Metallic-plastic Composite Water Barrier
It is a water barrier that is made up of a composite tape with a thin metallic layer of aluminum or aluminum foil contained in the plastics to wind along the cables.
2.0.6 Thermal Resistance
It is a physical quantity unit defined by the thermal ohm law for the one-dimensional head dispersion process using the analytic method for thermal network to calculate the current-carrying capacity of cables.
2.0.7 Auxiliary Ground Wire
It refers to conducting wire laid in parallel with HV single-core cable line and provided with ground wires at both ends to establish a circuit for induced current.
2.0.8 Direct Burying
It refers to a cable laying method that cables are laid down on the bottom of trenches and covered with soft soil layer and then with protection slabs to level the ground.
2.0.9 Cable Trough
It is a structure for cables that is closed without passage, but is provided with removable covers, and usual it is installed flush with the ground or a bit above or below the ground.
2.0.10 Channel
It is a trough structure with covers but the bottom may not be blocked to contain small quantity of cables without brackets, which can be arranged flush with the ground or can be placed on ground.
2.0.11 Tunnel
It is a fully closed structure for cables, which contains a relatively large quantity of cables and provided with passages for facilitating installation and patrol inspection.
2.0.12 Messanine (Cable floor)
It is a hall-type structure for cables, which is located below the control room floor and can accommodate many cable junctions and facilitate the installation activities.
2.0.13 Manhole
Cabin-type structure for cables that the people can access to for installing the accessories of cable joints, etc., or for operations of drawing cables.
2.0.14 Cable Structures
It is a general term for the structures of cable troughs, channels, tunnels, switch cabins, shafts, manholes, etc. provided for laying cables or installing accessories.
2.0.15 Slip Fixing
It is a fixing way to allow cables to have axial changes in angles along the fixing points caused by expansion and contraction due to temperature change and a slight cross sliding.
2.0.16 Rigid Fixing
It is a fixing way to clip cables that will not cause the cables to have a displacement with the expansion caused by heat and contraction by cold.
2.0.17 Snaking of Cable
It is a way to lay cables in a shape of waves to reduce the axial mechanical thermal stress according to the requirements of quantitative parameters.
2.0.18 Cantilever Bracket
It is a bracket made from rigid materials to support cables, which is in a form of cantilever.
2.0.19 Cable Tray
It is a general term for the rigid structure system that consists of the straight sections, bends, assemblies of trays or ladders, and cantilever brackets, hangers, etc. for connecting tightly and supporting cables.
2.0.20 Cable Brackets
It is a general term for cable trays, common supports and hangers.
2.0.21 Fire Protection Pillows
They are expansion flexible fire-resistant objects in a shape of pillows, which are used to block or barrier fire.