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4.1.24. Switchgears installed in rooms accessible to uninstructed personnel must have live parts closed with solid fences.
In the case of using a switchgear with open current-carrying parts, it must be fenced. In this case, the fence must be mesh, solid or mixed with a height of at least 1.7 m. The distance from the mesh fence to non-insulated current-carrying parts of the device must be at least 0.7 m, and from solid - in accordance with 4.1.14. The width of the aisles is taken in accordance with the requirements given in 4.1.21.
4.1.25. The termination of wires and cables must be made so that it is inside the device.
4.1.26. Removable guards must be reinforced so that their removal is impossible without the use of a tool. Doors must be locked with a key.
4.1.27. Installation of complete switchgears and substations (KRU, KTP) must comply with the requirements given in Ch. 4.2 for KRU and PTS above 1 kV.
Outdoor switchgear installation
4.1.28. When installing switchgears outdoors, the following requirements must be observed:
1. The device must be located on a planned site at a height of at least 0.2 m from the planning level and must have a design that meets environmental conditions. In areas where snowdrifts of 1 m or more are observed, cabinets should be installed on elevated foundations.
2. Local heating must be provided in the cabinets to ensure the normal operation of devices, relays, measuring instruments and metering devices in accordance with the requirements of GOST.
Chapter 4.2
Switchgears and substations
Voltage above 1 kV
Scope, definitions
4.2.1. This chapter of the Rules applies to stationary switchgear and substations of alternating current with a voltage above 1 kV. The rules do not apply to special switchgears and substations regulated by special technical conditions, and to mobile electrical installations.
4.2.2. A switchgear is an electrical installation that serves to receive and distribute electricity and contains switching devices, combined and connecting buses, auxiliary devices (compressor, battery, etc.), as well as protection devices, automation and measuring instruments.
An open switchgear (ORU) is a switchgear, all or the main equipment of which is located in the open air.
A closed switchgear (ZRU) is a switchgear, the equipment of which is located in the building.
4.2.3. A complete switchgear is a switchgear, consisting of fully or partially closed cabinets or blocks with built-in devices, protection and automation devices, supplied assembled or fully prepared for assembly.
A complete switchgear intended for indoor installation is abbreviated as KRU. A complete switchgear designed for outdoor installation is abbreviated as KRUN.
4.2.4. A substation is an electrical installation that serves to convert and distribute electricity and consists of transformers or other energy converters, switchgears, control devices and auxiliary structures.
Depending on the predominance of one or another function of substations, they are called transformer or converter.
4.2.5. An attached substation (attached switchgear) is a substation (RU) that is directly adjacent (adjacent) to the main building.
4.2.6. A built-in substation (built-in switchgear) is a closed substation (closed switchgear) inscribed (inscribed) in the contour of the main building.
4.2.7. An intrashop substation is a substation located inside the production building (open or in a separate closed room).
4.2.8. A complete transformer (converting) substation is a substation consisting of transformers (converters) and blocks (KRU or KRUN and other elements) supplied assembled or fully prepared for assembly. Complete transformer (converting) substations (KTP, KPP) or parts of them, installed indoors, refer to indoor installations, installed outdoors - to outdoor installations.
4.2.9. A pole (mast) transformer substation is an open transformer substation, all the equipment of which is installed on structures or on overhead line supports at a height that does not require substation fencing.
4.2.10. A distribution point (DP) is a switchgear designed to receive and distribute electricity at one voltage without conversion and transformation, which is not part of a substation.
4.2.11. A chamber is a room intended for the installation of devices and tires.
A closed chamber is a chamber that is closed on all sides and has solid (not mesh) doors.
A fenced chamber is a chamber that has openings protected in whole or in part by non-continuous (mesh or mixed) fences.
Mixed fences are fences made of nets and solid sheets.
An explosion chamber is a closed chamber designed to localize possible emergency consequences in case of damage to the devices installed in it and having an exit to the outside or into the explosive corridor.
4.2.12. A service corridor is a corridor along the chambers or switchgear cabinets intended for servicing devices and tires.
The explosive corridor is the corridor into which the doors of the explosive chambers open.
Closed switchgear (ZRU)
Closed switchgears and substations.
Closed switchgears are most often constructed up to 10 kV inclusive. If it is difficult to obtain the site necessary for the placement of outdoor switchgear, when located at enterprises in cramped conditions, in areas with polluted air, which destroys open current-carrying parts and reduces the insulating properties of porcelain, as well as in northern regions with very low temperatures and heavy snowfalls, they build ZRU 35 and 110 kV. At the same time, ZRU 110 kV is constructed using equipment intended for outdoor switchgear.
Closed switchgears are placed in one-, two- or three-story buildings made of unified prefabricated reinforced concrete structures. Closed switchgears 6 and 10 kV and substations are placed in built-in, attached or detached buildings made of brick or precast concrete, constructed on foundations of reinforced concrete blocks.
Closed switchgears 35 and 110 kV are placed in separate buildings made of prefabricated reinforced concrete. The dimensions of the premises depend on the type of electrical equipment used, the scheme of the main circuits, the filling scheme and the permissible widths of the corridors and passages in the switchgear, transformer chambers and switchboard rooms (Table 4). When laying out indoor switchgear and substations, the current building standards and dimensions of typical elements made of precast concrete are taken into account: reinforced concrete slabs, beams, roofing and interfloor ceilings.
When designing indoor switchgear and substations, the requirements of the PUE are taken into account, the main of which are given below. The switchgear rooms are separated from other rooms by walls or partitions and ceilings. Switchgears above 1 and up to 1 kV, as a rule, are placed separately. Depending on the length of the switchgear room, one (with a length of up to 7 m) or two exits (with a length of more than 7 and up to 60 m) located at its ends is arranged (it is allowed to have exits from the switchgear at a distance of up to 7 m from its ends).
Switchgear doors open towards other rooms, outwards or towards a low voltage switchgear, and have self-locking locks that can be opened from the inside of the room without a key. Door thresholds are not allowed.
The greatest distribution in the installation of modern switchgear and substations of 6 and 10 kV received complete devices. Complete switchgears are assembled from prefabricated one-way service chambers (KSO-272 and KSO-366) or cabinets KRU-2-6, KRU-2-10, KR-Yu/500, K-XII, K-XV. They are supplied according to custom schemes with main circuit devices installed in chambers and cabinets, with protection, measurement, accounting and signaling devices, with full busbars and wiring of the secondary circuit within the chambers.
Open switchgear (OSG)
Oil switch in outdoor switchgear
Design features
An open switchgear (ORU) is a switchgear whose equipment is located outdoors. All outdoor switchgear elements are placed on concrete or metal bases. The distances between the elements are selected according to the PUE. At a voltage of 110 kV and above, under devices that use oil for operation (oil transformers, switches, reactors), oil receivers are created - gravel-filled recesses. This measure is aimed at reducing the likelihood of fire and reducing damage in case of an accident on such devices.
The busbars of the outdoor switchgear can be made both in the form of rigid pipes and in the form of flexible wires. Rigid pipes are mounted on racks using support insulators, and flexible pipes are suspended on portals using suspension insulators.
The territory on which the outdoor switchgear is located is mandatory fenced off.
Advantages
§ Switchgears allow the use of arbitrarily large electrical devices, which, in fact, determines their use at high voltage classes.
§ Production of outdoor switchgear does not require additional costs for the construction of premises.
§ Outdoor switchgear is more convenient than indoor switchgear in terms of expansion and modernization
§ It is possible to visually observe all outdoor switchgear devices
Flaws
§ The operation of the switchgear is difficult in adverse weather conditions, in addition, the environment has a stronger effect on the elements of the switchgear, which leads to their early wear.
§ Outdoor switchgear takes up much more space than switchgear.
A complete switchgear (KRU) is a switchgear assembled from standard unified blocks (so-called cells) of a high degree of readiness, assembled at the factory. At voltages up to 35 kV, cells are made in the form of cabinets connected by side walls in a common row. In such cabinets, elements with voltages up to 1 kV are made with wires in solid insulation, and elements from 1 to 35 kV are made with air-insulated conductors.
For voltages above 35 kV, air insulation is not applicable, therefore, elements under high voltage are placed in sealed chambers filled with SF6 gas. Cells with SF6 chambers have a complex structure that looks like a network of pipelines. Gas-insulated switchgear is abbreviated as GIS.
Application area
Complete switchgears can be used for both indoor and outdoor installation (in this case they are called KRUN). KRU are widely used in cases where compact placement of the switchgear is required. In particular, switchgear is used at power stations, urban substations, for powering oil industry facilities (oil pipelines, drilling rigs), in power consumption schemes for ships.
KRU, in which all the devices are located in one compartment, is called the chamber of the one-way service team (KSO). As a rule, KSO is really one-sided service, most often it has open busbars, there is no back wall.
KRU device 
As a rule, the switchgear cabinet is divided into 4 main compartments: 3 high-voltage - cable compartment (input or line), switch compartment and busbar compartment and 1 low-voltage - relay cabinet.
§ The relay compartment (3) contains low-voltage equipment: RPA devices, switches, knife switches. On the door of the relay compartment, as a rule, there are light-signal fittings, devices for accounting and measuring electricity, and control elements of the cell.
§ In the switch compartment (4) there is a power switch or other high-voltage equipment (disconnecting contacts, fuses, VTs). Most often, in switchgear, this equipment is placed on a withdrawable or withdrawable element.
§ In the busbar compartment (6) there are power busbars (8) connecting switchgear section cabinets.
§ Input compartment (5) is used to accommodate cable terminations, measuring current transformers (7), voltage transformers, surge arresters.
RU up to 1000V.
The main type of switchgear with voltage up to 1000 V are switchboards. With their help, they supply external loads and substations' own needs. Switchboards are diverse in terms of schemes and devices and devices installed in them. Shields are completed from panels or cabinets interconnected in quantities and combinations corresponding to the design scheme and the building part of the shield room. The panel (or cabinet) is a completely finished element of the shield, and the shield as a whole is a complete electrical device.
The panel is a metal structure (frame with a front panel), on which devices and devices for switching, measurement and protection are installed. The shield panels are connected by busbars and wiring of secondary circuits, to which the equipment mounted on the panels is connected. They are divided into introductory, linear and sectional, depending on the purpose of the devices installed on them, as well as end, the purpose of which is the protective and decorative closure of the sides of the outer panels of the shield. Panels of all series are based on a single frame made of bent steel sheets with a thickness of 2-3 mm with parts made of steel bent profiles for fixing devices and the same design: two facade racks, an upper facade sheet for measuring instruments, doors for servicing devices installed on the frame inside, two rear pillars, transverse and longitudinal links. The handles of the drives of automatic machines and knife switches are brought to the facade of the panel through rectangular holes.
Installation of panels begins with marking the installation site of the foundation frame, which must be installed at the first stage of installation work. The passages between the wall and the shield are checked, the symmetrical arrangement of the longitudinal and transverse axes of the shield to the shield room, the interface with cable channels and openings, taking into account the mark of the clean floor.
The shields are installed after the completion of construction and finishing works on the foundation frame, calibrated in the horizontal and vertical planes and temporarily fixed. After installation, connection of blocks or panels to each other and alignment, the shield is finally fixed with bolts or welding. Mounting of busbars and installation of devices received in a separate package.
Switchgear (RU) - this is an electrical installation designed to receive and distribute electrical energy, containing electrical apparatus, tires and auxiliary devices. Power stations, step-down and step-up substations, usually have several switchgears of different voltages (RU VN, RU SN, RU NN).
Essentially, RU this is a constructive implementation of the adopted electrical circuit of the substation, i.e. arrangement of electrical devices indoors or outdoors with connections between them with bare (rarely insulated) tires or wires strictly in accordance with the electrical circuit.
For the energy system, the switchgear is a network node equipped with electrical devices and protective devices that serve to control the distribution of energy flows, disconnect damaged sections, and ensure reliable power supply to consumers.
Each switchgear consists of suitable and outgoing connections, which are interconnected by busbars, jumpers, ring and polygonal connections, with the placement of a different number of switches, disconnectors, reactors, instrument transformers and other electrical devices, due to the adopted scheme. All similar connections are made in the same way, so that the switchgear is assembled from standard, as it were, typical cells.
The switchgear must meet certain requirements, the most important of which are: reliability of operation, convenience and safety of maintenance with minimal construction costs, fire safety and operational efficiency, the possibility of expansion, the maximum use of large-block prefabricated units.
The reliability of the switchgear operation is ensured by the correct choice and correct installation of electrical equipment (electrical apparatus, current-carrying parts and insulators), as well as good localization of accidents with electrical equipment in case of their occurrence. In addition, the reliability of the operation of the switchgear to a greater extent depends on the quality of construction and electrical installation work.
Switchgears are made for all applied voltages. By analogy with devices, they are divided into switchgear up to 1000 kV, high voltage switchgear from 3 to 220 kV, ultra-high voltage switchgear: 330, 500, 750 kV and advanced ultra-high voltage switchgear of 1150 kV and above.
By design, switchgears are divided into closed (internal), in which all electrical equipment is located inside the building, and open (outdoor), in which all electrical equipment is located in the open air.
Rice. 2.1. GRU 6 - 10 kV with one busbar system and group reactors (section of the generator and group reactor circuits) 1 - current transformer, 2 - bushing, 3 - generator circuit breaker chamber, 4 - circuit breaker drive, 5 - busbar block, 6 - busbar disconnector block, 7 - busbar disconnector drive, 8 - double reactor chamber, 9 - busbar, 10 - KRU cells
Closed switchgear (ZRU) is a switchgear located inside the building. Usually they are built at a voltage of 3 - 20 kV. In high voltage installations, 35 - 220 kV, indoor switchgears are built only with a limited area under the switchgear, when they are located in close proximity to industrial enterprises that pollute the air with conductive dust or gases that destroy insulation and metal parts of electrical equipment, as well as near sea coasts and in areas with very low air temperatures (regions of the Far North).
Maintenance of ZRU should be convenient and safe. For safety, the minimum allowable distances from current-carrying parts to various elements of the switchgear are observed
Uninsulated current-carrying parts, in order to avoid accidental contact with them, must be placed in chambers or fenced. The fence can be solid or mesh. Many indoor switchgear use mixed fencing - the drives of switches and disconnectors are mounted on the solid part of the fencing, and the mesh part of the fencing allows you to monitor the equipment. The height of such a fence must be at least 1.9 m, while the nets must have holes no larger than 25 × 25 mm, and the fences must be locked.
From the switchgear premises, exits to the outside or to premises with fireproof walls and ceilings are provided: one exit with a switchgear length of up to 7 m; two exits at the ends with a length of 7÷60 m; with a length of more than 60 m - two exits at the ends and additional exits so that the distance from any point of the corridor to the exit does not exceed 30 m. The switchgear doors must open outward, have self-locking locks and open without a key from the switchgear side.
ZRU must ensure fire safety. When oil transformers are installed in switchgear, measures are provided for collecting and draining oil into the oil collecting system. The closed switchgear provides for natural ventilation of transformer and reactor rooms, as well as emergency exhaust of service corridors for open chambers with oil-filled equipment.
Prefabricated switchgear (SBRU) mounted from enlarged units (cabinets, panels, etc.) manufactured and completed at factories or workshops. In the SBRU, the building is constructed in the form of a box, without any partitions, of a hall type. The basis of the chambers is a steel frame, and the partitions between the chambers are made of asbestos-cement or gypsum boards.
Rice. 2.2. ZRU 110 kV of the hall type (section of the air circuit breaker cell)1 - VNV-110 kV circuit breaker, 2 - first bus system, 3 - bus disconnectors, 4 - second bus system, 5 - bypass bus system, 6 - bypass disconnector, 7 - coupling capacitor, 8 - line disconnector.
Complete switchgear (KRU) - this switchgear is completely manufactured in factories, consisting of closed cabinets with built-in devices, measuring and protective devices and auxiliary devices; in place, all elements of the switchgear are only mounted. These switchgears are the most suitable for the industrialization of power construction, so they are becoming the most common form of switchgear at present. The use of KRU allows you to speed up the installation of the switchgear. The switchgear is safe to maintain, since all live parts are covered with a metal casing. Air, oil, pyralene, solid insulation, inert gases can be used as insulation between current-carrying parts in switchgear. Switchgear with oil and gas insulation can be manufactured for high voltages of 220 - 500 kV. Our industry produces switchgear 3 - 35 kV with air insulation and 110 - 220 kV with SF6 insulation (in world practice up to 800 kV). Complete switchgears for outdoor installation (KRUN) are designed for open installation outsidepremises. KRUN consist of metal cabinets with devices, instruments, protection and control devices built into them. KRUN are designed for operation at ambient temperatures from -40 to +35 °С and air humidity not more than 80%. KRUN can have a stationary installation of a circuit breaker in a cabinet or a roll-out trolley with a circuit breaker, similar to indoor KRU.
Cabinets KRZ-10 (Fig. 2.3) for outdoor installation 6 - 10 kV are designed for networks of agriculture, industry and electrification of railway transport. Cases KRZ-10 are designed for ambient temperature from +50 to -45°C.
At the same time, mixed-type switchgears are also being widely constructed, partly as prefabricated and partly as complete.
Rice. 2. 4. Typical layout of outdoor switchgear 110 - 220 kV for a circuit with two working and bypass bus systems
1 - bypass SL, 2 - SSS disconnector, 3 - coupling capacitor, 4 - barrier, 5 - line disconnector, 6 - current transformer, 7 - air circuit breaker, 8 - second SS, 9 - keel-mounted busbar disconnectors, 10 - busbar disconnectors , 11 – the first SS.
Open switchgear (OSG)- This is a switchgear located in the open air. As a rule, switchgears in electrical installations with a voltage of 35 and above are built open. The simplest open substations of small power with a primary voltage of 10 (6) -35 kV are also widespread for the electrification of agricultural and suburban areas, industrial villages and small towns.
All devices in the outdoor switchgear are made on low bases (metal or reinforced concrete). Across the territory of the outdoor switchgear, driveways are made for the possibility of mechanizing the installation and repair of equipment. Busbars can be flexible from stranded wires or from rigid pipes. Flexible busbars are mounted with suspension insulators on portals, and rigid busbars with support insulators on reinforced concrete or metal racks.
The use of a rigid busbar makes it possible to refuse portals and reduce the area of the outdoor switchgear.
Under power transformers, oil reactors and tank circuit breakers of 110 kV and above, an oil receiver is provided, a layer of gravel with a thickness of at least 25 cm is laid, and the oil drains into underground oil collectors in emergency cases. Cables for operational circuits, control circuits, relay protection, automation and air ducts are laid in trays made of reinforced concrete structures without being buried in the soil or in metal trays suspended from outdoor switchgear structures.
The switchgear must be fenced.
Advantages of outdoor switchgear compared to closed switchgear
1) a smaller volume of construction work; so only the preparation of the site, the construction of roads, the construction of foundations and the installation of supports are necessary;
2) significant savings in building materials (steel, concrete);
3) lower capital costs;
4) shorter construction time;
5) good visibility;
6) ease of expansion and ease of replacement of equipment with others with smaller or larger dimensions, as well as the ability to quickly dismantle old and install new equipment.
7) less risk of damage spreading due to large distances between devices of adjacent circuits;
Disadvantages of outdoor switchgear compared to indoor switchgear
1) less convenient maintenance, since the switching of the disconnectors and the observation of the devices are carried out in the air in any weather (low temperatures, bad weather);
2) a large area of the structure;
3) exposure of devices to a sharp change in ambient temperature, their exposure to pollution, dust, etc., which complicates their operation and forces the use of devices of a special design (for outdoor installation), more expensive.
The cost of ZRU is usually 10 - 25% higher than the cost of the corresponding outdoor switchgear.
At present, in most cases, outdoor switchgear of the so-called low type is used, in which all devices are located in the same horizontal plane and are installed on special bases of a relatively small height; busbars are also fixed on supports of relatively small height.
An electrical installation, which is made up of transformers or other energy converters, switchgears with voltage up to 1000 V and above for the conversion and distribution of electricity, is called a substation.
Depending on the purpose, substations can be transformer (TP) or converter (PP) - rectifying.
Transformer substations are the main link in the power supply system. Depending on the position in the power system, purpose, the value of the primary and secondary voltage, they can be divided into District substations, substations of industrial enterprises, Traction substations, substations of the city ELECTRIC network, etc.
District and nodal substations are powered by district (main) networks of the energy system and designed to supply large areas in which there are fishing, urban, agricultural and other consumers of electricity. The primary voltage of regional substations is 750, 500, 330, 220, 150 and 110 kV, and the secondary voltage is 220, 150, 110, 35, 20, 10 or 6 kV.
The following types of transformer substations are located on the territory of industrial enterprises.
1. Factory substations, WHICH are executed as:
a) The main step-down substations and substations of deep introduction with an open switchgear (RP) for receiving electricity from power systems with a voltage of 110-35 kV and turning it into the voltage of the factory network of 6-10 kV to power workshop and inter-shop substations and powerful consumers;
b) substations and distribution points from closed distribution centers, with the installation of high-voltage equipment for 6-10 kV on them.
2. Workshop substations designed to power one or more workshops are performed:
a) that they stand separately, attached and built-in with the installation of transformers in closed chambers and switchboards for a voltage of 0.4-0.23 kV;
b) intrashop, mainly as a complete transformer-converter with the installation of one or two transformers with a capacity of 400 kW and more, located in a separate room of the shop or directly in the shop, depending on environmental conditions and the nature of production.
Main electrical equipment of substations:
power transformers; autotransformers; conductive parts of high-voltage equipment (insulators, bushings, disconnector, fuse, switches, switch leads. voltage transformers; arrester.
Each substation has switchgears (RP) that contain switching devices, protection and automation devices, measuring instruments, assembly and connecting busbars, auxiliary devices.
According to the constructive implementation, the RP is divided into open and closed. They can be complete (collector at the factory) or prefabricated (collector partially or completely at the site of use.
Open switchgear (ORU) - such a device in which all or the main equipment is located in the open air; CLOSED switchgear (ZRU) - a device whose equipment is located in the building.
Complete switchgear (KRP) - a switchgear, which is made up of cabinets, fully or partially closed, or blocks with built-in devices, protection and automation devices, measuring instruments and auxiliary devices, which is supplied assembled or fully prepared for collections and intended for indoor installation.
The complete switchgear of external installation (KRPZU) is a KRP intended for external installation.
A complete transformer (converting) substation (KTP) is a substation that is made up of transformers (converter) and KRP or KRPZU blocks, which are supplied assembled or fully prepared for collections.
Distribution switching point (RP) - a switchgear designed to receive and distribute electricity at one voltage without conversion and transformation.
Chamber - a room intended for the installation of devices and tires: a closed chamber - closed on all sides and has solid (not mesh) doors. The protected chamber has openings, protected in whole or in part by non-continuous (mesh or mixed) fences.
Each substation has three main nodes: high voltage switchgear, transformer and low voltage switchgear.
Complain
Section 4. Switchgears and substations
Chapter 4.2. Switchgears and substations with voltages above 1 kV
Closed switchgears and substations
4.2.81. Closed switchgears and substations can be located both in separate buildings and be built-in or attached. An extension of the substation to an existing building using the wall of the building as the wall of the substation is allowed, provided that special measures are taken to prevent the violation of the waterproofing of the joint during the settlement of the attached substation. The specified draft must also be taken into account when attaching the equipment to an existing building wall.
Additional requirements for the construction of built-in and attached substations in residential and public buildings, see Chapter 7.1.
4.2.82. In the premises of ZRU 35-220 kV and in closed chambers of transformers, stationary devices or the possibility of using mobile or inventory lifting devices for mechanization of repair work and maintenance of equipment should be provided.
In rooms with switchgear, a platform for repair and adjustment of roll-out elements should be provided. The repair site shall be equipped with facilities for testing circuit breaker drives and control systems.
4.2.83. Closed switchgear of different voltage classes, as a rule, should be placed in separate rooms. This requirement does not apply to PTS 35 kV and below, as well as to GIS.
It is allowed to place a switchgear up to 1 kV in the same room with a switchgear above 1 kV, provided that parts of the switchgear or substation up to 1 kV and above will be operated by one organization.
Premises of switchgear, transformers, converters, etc. must be separated from service and other auxiliary premises (for exceptions, see chapters 4.3, 5.1 and 7.5).
4.2.84. When assembling the switchgear in the indoor switchgear, service platforms at different levels should be provided if they are not supplied by the manufacturer.
4.2.85. Transformer rooms and ZRU are not allowed to be placed:
1) under the premises of production with a wet technological process, under showers, baths, etc.;
2) directly above and below the premises, in which more than 50 people can be simultaneously located within the area occupied by the switchgear or transformer premises. in a period of more than 1 hour. This requirement does not apply to transformer rooms with dry transformers or non-combustible filling, as well as switchgear for industrial enterprises.
4.2.86. Clear distances between uninsulated current-carrying parts of different phases, from uninsulated current-carrying parts to grounded structures and fences, floors and ground, as well as between unshielded current-carrying parts of different circuits must be at least the values given in Table 4.2.7 (Fig. 4.2. 14-4.2.17).
Flexible busbars in switchgear should be checked for their convergence under the action of short-circuit currents in accordance with the requirements of 4.2.56.
Table 4.2.7. The smallest clear distances from current-carrying parts to various elements of ZRU (substations) 3-330 kV, protected by arresters, and ZRU 110-330 kV, protected by surge arresters 1, (in the denominator) (Fig. 4.2.14-4.2.17)
| Figure number | Distance name | Designation | Insulating distance, mm, for rated voltage, kV |
||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| From live parts to grounded structures and parts of buildings | 700
| 1100
| 1700
| 2400
|
|||||||
| Between conductors of different phases | A f-f | 800
| 1200
| 1800
| 2600
|
||||||
| From live parts to solid fences | 730
| 1130
| 1730
| 2430
|
|||||||
| From live parts to mesh fences | 800
| 1200
| 1800
| 2500
|
|||||||
| Between unshielded current-carrying parts of different circuits | 2900
| 3300
| 3800
| 4600
|
|||||||
| From unshielded live parts to the floor | 3400
| 4200
| |||||||||
| From unprotected outlets from the ZRU to the ground when they exit outside the territory of the outdoor switchgear and in the absence of vehicles passing under the outlets | 5500
| 6000
| 6500
| 7200
|
|||||||
| From the contact and disconnector blade in the open position to the busbar attached to the second contact | 900
| 1300
| 2000
| 3000
|
|||||||
| From unshielded cable outlets from indoor switchgear to the ground when cables exit to a support or portal not on the territory of the outdoor switchgear and in the absence of vehicles passing under the outlets | 3800
| 4500
| 5750
| 7500
|
|||||||
1 Surge arresters have a protective level of switching overvoltage phase-to-earth 1.8 U f.
Fig.4.2.14. The smallest clear distances between non-insulated current-carrying parts of different phases in the indoor switchgear and between them and grounded parts (according to Table 4.2.9)
Fig.4.2.15. The smallest distances between non-insulated live parts in ZRU and solid fences (according to Table 4.2.9)
4.2.87. The distance from the moving contacts of the disconnectors in the off position to the busbar of its phase connected to the second contact must be at least F
Fig.4.2.16. The smallest distances from non-insulated current-carrying parts in ZRU to mesh fences and between non-insulated non-insulated current-carrying parts of different circuits (according to Table 4.2.9)
4.2.88. Bare current-carrying parts must be protected from accidental contact (placed in chambers, fenced with nets, etc.).
When placing uninsulated current-carrying parts outside the chambers and placing them below the D size according to Table 4.2.7 from the floor, they must be protected. The height of the passage under the fence must be at least 1.9 m (Fig. 4.2.17).
Fig.4.2.17. The smallest distances from the floor to unshielded non-insulated current-carrying parts and to the lower edge of the porcelain of the insulator and the height of the passage in the indoor switchgear. The smallest distance from the ground to unenclosed linear outlets from the closed switchgear outside the outdoor switchgear and in the absence of vehicles passing under the outlets
Current-carrying parts located above the fences up to a height of 2.3 m from the floor should be located in the plane of the fence at the distances given in Table 4.2.7 for the size V(see Fig.4.2.16).
Apparatuses in which the lower edge of porcelain (polymeric material) of insulators is located above the floor level at a height of 2.2 m or more may not be fenced if the above requirements are met.
The use of barriers in enclosed cells is not allowed.
4.2.89. Unshielded uninsulated leading parts of various circuits, located at a height exceeding the size D according to Table 4.2.7, they must be located at such a distance from each other that after disconnecting any circuit (for example, a bus section), its safe maintenance is ensured in the presence of voltage in neighboring circuits. In particular, the distance between unshielded current-carrying parts located on both sides of the service corridor must correspond to the size G according to Table 4.2.7 (see Fig. 4.2.16).
4.2.90. The width of the service corridor should provide convenient maintenance of the installation and the movement of equipment, and it should be at least (counting in the clear between the fences): 1 m - with a one-sided location of the equipment; 1.2 m - with a two-sided arrangement of equipment.
In the service corridor where the switches or disconnectors are located, the above dimensions must be increased to 1.5 and 2 m, respectively. With a corridor length of up to 7 m, the width of the corridor for two-way service can be reduced to 1.8 m.
4.2.91. The width of the service corridor for switchgear with withdrawable elements and PTS should ensure the convenience of control, movement and turn of equipment and its repair.
When installing switchgear and PTS in separate rooms, the width of the service corridor should be determined based on the following requirements:
- with a single-row installation - the length of the largest of the switchgear bogies (with all protruding parts) plus at least 0.6 m;
- with a two-row installation - the length of the largest of the switchgear bogies (with all protruding parts) plus at least 0.8 m.
If there is a corridor on the back of the switchgear and PTS for their inspection, its width must be at least 0.8 m; individual local narrowings of no more than 0.2 m are allowed.
In case of open installation of switchgear and package transformer substation in industrial premises, the width of the free passage should be determined by the location of the production equipment, ensure the possibility of transporting the largest elements of the switchgear to the package transformer substation, and in any case it should be at least 1 m.
The height of the room must be at least the height of the switchgear, PTS, counting from busbar entries, jumpers or protruding parts of cabinets, plus 0.8 m to the ceiling or 0.3 m to the beams.
A lower height of the room is allowed, if at the same time the convenience and safety of replacing, repairing and adjusting switchgear, PTS equipment, busbar entries and jumpers are ensured.
4.2.92. The design loads on the floors of the premises along the path of transportation of electrical equipment should be taken into account the mass of the heaviest equipment (for example, a transformer), and the openings should correspond to their dimensions.
4.2.93. For air inlets to ZRU, KTP and closed substations that do not cross driveways or places where traffic is possible, etc., the distance from the lowest point of the wire to the ground surface must be at least E(Table 4.2.7 and Figure 4.2.17).
At smaller distances from the wire to the ground, in the corresponding section under the input, either fencing of the territory with a fence 1.6 m high or a horizontal fence under the input should be provided. In this case, the distance from the ground to the wire in the plane of the fence must be at least E.
For air inlets crossing passages or places where traffic is possible, etc., the distances from the lowest point of the wire to the ground should be taken in accordance with 2.5.212 and 2.5.213.
For air outlets from the ZRU to the territory of the outdoor switchgear, the indicated distances should be taken according to Table 4.2.5 for the size G(see Fig.4.2.6).
The distances between adjacent linear terminals of two circuits must be at least the values given in Table 4.2.3 for the size D, if partitions are not provided between the terminals of adjacent circuits.
On the roof of the indoor switchgear building, in case of an unorganized drain over the air inlets, visors should be provided.
4.2.94. Exits from the switchgear should be performed based on the following requirements:
1) with a switchgear length of up to 7 m, one exit is allowed;
2) with a switchgear length of more than 7 to 60 m, two exits should be provided at its ends; it is allowed to locate exits from the switchgear at a distance of up to 7 m from its ends;
3) with a switchgear length of more than 60 m, in addition to exits at its ends, additional exits should be provided so that the distance from any point of the service corridor to the exit is no more than 30 m.
Exits can be made to the outside, to the stairwell or to another industrial premises of the category G or D, as well as in other compartments of the switchgear, separated from this one by a fire door of the II degree of fire resistance. In multi-storey switchgears, the second and additional exits can also be provided to a balcony with an external fire escape.
Gates of cells with a leaf width of more than 1.5 m must have a gate if they are used for the exit of personnel.
4.2.95. The floors of the switchgear rooms are recommended to be carried out over the entire area of each floor at the same level. The design of the floors must exclude the possibility of the formation of cement dust. Thresholds in doors between individual rooms and in corridors are not allowed (for exceptions, see 4.2.100 and 4.2.103).
4.2.96. Doors from the switchgear should open towards other rooms or outward and have self-locking locks that can be opened without a key from the side of the switchgear.
Doors between compartments of one switchgear or between adjacent rooms of two switchgear should have a device that locks the doors in the closed position and does not prevent the doors from opening in both directions.
Doors between rooms (compartments) of switchgear of different voltages should open towards the switchgear with low voltage.
Locks in the doors of switchgear rooms of the same voltage must be opened with the same key; the keys to the entrance doors of the switchgear and other rooms should not fit the locks of the chambers, as well as the door locks in the enclosures of electrical equipment.
The requirement to use self-locking locks does not apply to switchgears of urban and rural distribution electrical networks with a voltage of 10 kV and below.
4.2.97. The enclosing structures and partitions of the KRU and KTP for the auxiliary needs of the power plant should be made of non-combustible materials.
It is allowed to install switchgear and package transformer substation for own needs in technological premises of substations and power plants in accordance with the requirements of 4.2.121.
4.2.98. In one switchgear room with a voltage of 0.4 kV and above, it is allowed to install up to two oil-immersed transformers with a capacity of up to 0.63 MV A each, separated from each other and from the rest of the switchgear room by a partition made of non-combustible materials with a fire resistance limit of 45 min. transformer, including higher voltage inputs.
4.2.99. Devices related to starting devices for electric motors, synchronous compensators, etc. (switches, starting reactors, transformers, etc.) may be installed in a common chamber without partitions between them.
4.2.100. Voltage transformers, regardless of the mass of oil in them, can be installed in enclosed switchgear chambers. At the same time, a threshold or ramp should be provided in the chamber, designed to hold the full volume of oil contained in the voltage transformer.
4.2.101. Cells of switches should be separated from the service corridor by solid or mesh fences, and from each other by solid partitions made of non-combustible materials. These switches must be separated from the drive by the same partitions or shields.
Under each oil circuit breaker with an oil mass of 60 kg or more in one pole, an oil receiver device is required for the full volume of oil in one pole.
4.2.102. In closed stand-alone, attached and built-in production facilities of the substation, in the chambers of transformers and other oil-filled devices with an oil mass of up to 600 kg in one tank, when the chambers are located on the ground floor with doors facing the outside, oil collectors are not made.
When the mass of oil or non-combustible environmentally friendly dielectric in one tank is more than 600 kg, an oil receiver must be arranged, designed for the full volume of oil or for holding 20% of the oil with a drain to the oil collector.
4.2.103. When constructing chambers above the basement, on the second floor and above (see also 4.2.118), as well as when arranging an exit from the chambers to the corridor under transformers and other oil-filled apparatus, oil receivers must be made according to one of the following methods:
1) when the mass of oil in one tank (pole) is up to 60 kg, a threshold or ramp is made to hold the full volume of oil;
2) with a mass of oil from 60 to 600 kg, an oil receiver is installed under the transformer (apparatus), designed for the full volume of oil, or at the exit from the chamber - a threshold or ramp to hold the full volume of oil;
3) with an oil mass of more than 600 kg:
- oil receiver containing at least 20% of the total oil volume of the transformer or apparatus, with oil drained to the oil sump. Oil drain pipes from oil receivers under transformers must have a diameter of at least 10 cm. On the side of oil receivers, oil drain pipes must be protected with nets. The bottom of the oil receiver should have a slope of 2% towards the pit;
- oil receiver without oil drain to the oil sump. In this case, the oil receiver must be covered with a grate with a 25 cm thick layer of clean washed granite (or other non-porous rock) gravel or crushed stone with a fraction of 30 to 70 mm and must be designed for the full volume of oil; The oil level must be 5 cm below the grate. The upper level of gravel in the TV receiver under the transformer should be 7.5 cm below the opening of the air supply ventilation duct. The area of the oil receiver must be larger than the area of the base of the transformer or apparatus.
4.2.104. Ventilation of the premises of transformers and reactors should ensure the removal of heat generated by them in such quantities that when they are loaded, taking into account the overload capacity and the maximum design ambient temperature, the heating of transformers and reactors does not exceed the maximum allowable value for them.
Ventilation of the rooms of transformers and reactors should be carried out in such a way that the temperature difference between the air leaving the room and entering it does not exceed: 15 ° C for transformers, 30 ° C for reactors for currents up to 1000 A, 20 ° C for reactors currents over 1000 A.
If it is impossible to provide heat exchange by natural ventilation, it is necessary to provide for forced ventilation, and at the same time, control of its operation using signaling devices should be provided.
4.2.105. Supply and exhaust ventilation with an intake at the floor level and at the level of the upper part of the room should be carried out in the room where the switchgear and SF6 cylinders are located.
4.2.106. The switchgear rooms containing equipment filled with oil, SF6 or compound must be equipped with exhaust ventilation switched on from the outside and not connected to other ventilation devices.
In places with low winter temperatures, the supply and exhaust ventilation openings must be equipped with insulated valves that can be opened from the outside.
4.2.107. In rooms where duty personnel stay for 6 hours or more, the air temperature must be not lower than +18 °С and not higher than +28 °С.
In the repair area of the indoor switchgear, a temperature of at least +5 °C must be provided for the duration of the repair work.
When heating rooms with SF6 equipment, heaters with a heating surface temperature exceeding 250 °C (for example, heaters of the TEN type) should not be used.
4.2.108. Holes in building envelopes and premises after laying electrical conductors and other communications should be sealed with a material that provides fire resistance not lower than the fire resistance of the building envelope itself, but not less than 45 minutes.
4.2.109. Other openings in the outer walls to prevent the entry of animals and birds must be protected with nets or gratings with cells measuring 10x10 mm.
4.2.110. Overlapping of cable channels and double floors must be made with removable plates of fireproof materials flush with the clean floor of the room. The mass of a separate floor slab should be no more than 50 kg.
4.2.111. Laying transit cables and wires in the chambers of devices and transformers, as a rule, is not allowed. In exceptional cases, they may be laid in pipes.
Wiring for lighting and control circuits and measurements located inside the chambers or located near non-insulated current-carrying parts may only be allowed to the extent necessary for making connections (for example, to instrument transformers).
4.2.112. The laying of heating pipelines related to them (non-transit) in the premises of the switchgear is allowed provided that solid welded pipes without valves, etc. are used, and ventilation welded ducts - without valves and other similar devices. Transit laying of heating pipelines is also allowed, provided that each pipeline is enclosed in a continuous waterproof shell.
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