Special requirements for cable management of power plants, substations and switchgears

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Section 2. Sewerage of electricity

Cable lines up to 220 kV. Special requirements for cable management of power plants, substations and switchgears

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Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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2.3.76. The requirements given in 2.3.77-2.3.82 apply to cable facilities of thermal and hydroelectric power plants with a capacity of 25 MW or more, switchgears and substations with a voltage of 220-500 kV, as well as switchgears and substations of particular importance in the power system (see. also 2.3.113).

2.3.77. The main electrical connection diagram, auxiliary circuit and operating current circuit, equipment control and layout of equipment and cable facilities of a power plant or substation must be carried out in such a way that in the event of fires in the cable facilities or outside it, disruption of the operation of more than one unit of the power plant, simultaneous loss of mutually redundant connections of distribution devices and substations, as well as failure of fire detection and extinguishing systems.

2.3.78. For the main cable flows of power plants, cable structures (floors, tunnels, shafts, etc.) should be provided, isolated from process equipment and excluding access to cables by unauthorized persons.

When placing cable flows at power plants, cable line routes should be selected taking into account:

preventing overheating of cables from heated surfaces of process equipment;
prevention of damage to cables during exhausts (fires and explosions) of dust through the safety devices of dust systems;
preventing the laying of transit cables in technological tunnels for hydraulic ash removal, chemical water treatment facilities, as well as in places where pipelines with chemically aggressive liquids are located.

2.3.79. Mutually redundant critical cable lines (power, operational current, communications, control, signaling, fire extinguishing systems, etc.) should be laid so that during fires the possibility of simultaneous loss of mutually redundant cable lines is excluded. In sections of the cable industry, where the occurrence of an accident threatens its great development, cable flows should be divided into groups isolated from one another. The distribution of cables into groups is accepted depending on local conditions.

2.3.80. Within one power unit, it is allowed to build cable structures with a fire resistance limit of 0,25 hours. At the same time, technological equipment that can serve as a source of fire (tanks with oil, oil stations, etc.) must have fences with a fire resistance limit of at least 0,75 h, excluding the possibility of ignition of cables in the event of a fire on this equipment.

Within one power unit of a power plant, it is allowed to lay cables outside special cable structures, provided that they are reliably protected from mechanical damage and dust, from sparks and fire during the repair of process equipment, ensuring normal temperature conditions for cable lines and ease of maintenance.

To provide access to cables when they are located at a height of 5 m or more, special platforms and passages should be constructed.

For single cables and small groups of cables (up to 20), operational sites may not be built, but it must be possible to quickly replace and repair cables in the field.

When laying cables within one power unit outside special cable structures, it should be ensured, if possible, that they are divided into separate groups passing along different routes.

2.3.81. Cable floors and tunnels, in which the cables of various power units of the power plant are located, including cable floors and tunnels under block control panels, must be divided by blocks and separated from other rooms, cable floors, tunnels, shafts, ducts and channels by fireproof partitions and ceilings with a fire resistance limit not less than 0,75 h, including in places where cables pass.

In places where cables are supposed to pass through partitions and ceilings, in order to ensure the possibility of replacement and additional laying of cables, a partition made of fireproof, easily pierced material with a fire resistance of at least 0,75 hours should be provided.

In extended cable structures of thermal power plants, emergency exits should be provided, located, as a rule, at least 50 m apart.

Cable facilities of power plants must be separated from outgoing network cable tunnels and collectors by fireproof partitions with a fire resistance limit of at least 0,75 hours.

2.3.82. The places where cables enter the rooms of closed switchgears and in the room of control and protection panels of open switchgears must have partitions with a fire resistance limit of at least 0,75 hours.

The places where cables enter the block control panels of power plants must be closed with partitions with a fire resistance limit of at least 0,75 hours.

Cable shafts must be separated from cable tunnels, floors and other cable structures by fireproof partitions with a fire resistance of at least 0,75 hours and have ceilings at the top and bottom. Extended shafts when passing through ceilings, but at least every 20 m, should be divided into compartments by fireproof partitions with a fire resistance of at least 0,75 hours.

Passage cable shafts must have entrance doors and be equipped with ladders or special brackets.

See other articles Section Rules for the installation of electrical installations (PUE).

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