Switchgear (RU) is an electrical installation designed to receive and distribute electrical energy, containing electrical devices, buses and auxiliary devices. Electrical stations, step-down and step-up substations, usually have several switchgears of different voltages (HV switchgear, LV switchgear, LV switchgear).
Essentially RU - this is a constructive implementation of accepted electrical diagram substations, i.e. placement of electrical devices indoors or on outdoors with connections between them by bare (rarely insulated) busbars or wires strictly in accordance with the electrical diagram.
For the energy system, the reactor plant is a network node equipped with electrical devices and protective devices that serve to control the distribution of energy flows, disconnect damaged areas, 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 determined by the adopted circuit. All similar connections are made in the same way, so the switchgear is assembled from standard, seemingly standard, cells.
RU must meet certain requirements, the most important of them are: reliability of operation, convenience and safety of maintenance when minimum costs for construction, fire safety and economical operation, possibility of expansion, maximum use of large-block prefabricated units.
The reliability of the switchgear is ensured by the correct choice and correct installation electrical equipment (electrical devices, live parts and insulators), as well as good localization of accidents with electrical equipment if they occur. In addition, the reliability of the reactor plant largely depends on the quality of construction and electrical installation work.
RU are performed for all applicable voltages. By analogy with the 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 promising ultra-high voltage switchgear 1150 kV and higher.
According to their design, switchgears are divided into closed (internal), in which all electrical equipment is located inside the building, and open (external), in which all electrical equipment is located in the open air.
Rice. 2.1. GRU 6 – 10 kV with one bus system and group reactors (section along the generator and group reactor circuits) 1 - current transformer, 2 - bushing insulator, 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 duct, 10 – switchgear cells
Closed switchgear (SGD) - This is a distribution device located inside the building. They are usually built at a voltage of 3 – 20 kV. In high voltage installations, 35 - 220 kV, closed switchgears are constructed only with limited area under switchgear, when 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 indoor switchgear should be convenient and safe. For safety, the minimum permissible distances from live parts to various elements of the switchgear are observed.
To avoid accidental touching, uninsulated live parts must be placed in chambers or fenced. The fence can be solid or mesh. In many indoor switchgears, mixed fencing is used - the drives of switches and disconnectors are mounted on the solid part of the fencing, and the mesh part of the fencing allows observation of the equipment. The height of such a fence must be at least 1.9 m, while the mesh must have holes measuring no more than 25x25 mm, and the fences must be locked.
From the indoor switchgear rooms, exits are provided to the outside or to rooms with fireproof walls and ceilings: one exit for a switchgear length of up to 7 m; two exits at the ends with a length of 7÷60 m; for a length of more than 60 m - two exits at the ends and additional exits so that the distance from any point in 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.
The closed switchgear must ensure fire safety. When installing oil transformers in closed switchgear, measures are taken to collect and drain oil into the oil collection system. The ZRU provides natural ventilation rooms of transformers and reactors, as well as emergency exhaust of service corridors open cells with oil-filled equipment.
Prefabricated switchgear (SRU) assembled from enlarged units (cabinets, panels, etc.), manufactured and equipped in 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 cameras is steel frame, and the partitions between the chambers are made of asbestos-cement or gypsum boards.
Rice. 2.2. 110 kV indoor switchgear (section through an air circuit breaker cell)1 - VNV-110 kV circuit breaker, 2 - first busbar system, 3 - busbar disconnectors, 4 - second busbar system, 5 - bypass busbar system, 6 - bypass disconnector, 7 - coupling capacitor, 8 - line disconnector.
Complete switchgear (KRU) is a switchgear completely manufactured in factories, consisting of closed cabinets with built-in devices, measuring and protective devices and auxiliary devices; All switchgear elements are only mounted on site. These switchgears best meet the requirements of the industrialization of energy construction, so they are currently becoming the most common form of switchgear design. The use of switchgear 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, and inert gases can be used as insulation between live parts in switchgear. Switchgear with oil and gas insulation can be manufactured for high voltages of 220 - 500 kV. Our industry produces switchgear of 3 - 35 kV with air insulation and 110 - 220 kV with SF6 insulation (in world practice up to 800 kV). Complete outdoor switchgears (KRUN) are designed for open installation outsidepremises. KRUN consist of metal cabinets with built-in devices, instruments, protection and control devices. KRUN are designed to operate at ambient temperatures from -40 to +35 ° C and air humidity of no more than 80%. KRUN can have a stationary installation of the circuit breaker in a cabinet or a withdrawable trolley with a circuit breaker, similar to the switchgear indoor installation.
Cabinets KRZ-10 (Fig. 2.3) for outdoor installation 6 – 10 kV are intended for networks Agriculture, industry and electrification of railway transport. KRZ-10 cabinets are designed for ambient temperatures from +50 to -45°C.
At the same time, at present, mixed-type switchgears are also widely constructed, partly as prefabricated and partly as complete ones.
Rice. 2. 4. Typical layout of outdoor switchgear 110 - 220 kV for a circuit with two working and bypass bus systems
1 – bypass SB, 2 – SBH disconnector, 3 – coupling capacitor, 4 – arrester, 5 – linear disconnector, 6 – current transformer, 7 – air circuit breaker, 8 – second SB, 9 – keel-type bus disconnectors, 10 – bus disconnectors , 11 – first secondary school.
Open switchgear (OSD)- This is a distribution device located in the open air. As a rule, switchgear switchgears in electrical installations with voltages of 35 and above are constructed open. The simplest open substations of low 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 outdoor switchgear are installed on low foundations (metal or reinforced concrete). Passages are made through the territory of the outdoor switchgear to enable mechanization of installation and repair of equipment. Busbars can be flexible stranded wires or rigid pipes. Flexible busbars are secured using suspension insulators on portals, and rigid busbars are secured using support insulators on reinforced concrete or metal racks.
The use of rigid busbars makes it possible to abandon portals and reduce the area of outdoor switchgear.
An oil receiver is provided under power transformers, oil reactors and tank switches of 110 kV and above, a layer of gravel at least 25 cm thick is laid, and the oil flows in emergency cases into underground oil collectors. Cables of operational circuits, control circuits, relay protection, automation and air ducts are laid in trays made of reinforced concrete structures without burying them in the soil or in metal trays suspended from outdoor switchgear structures.
The outdoor switchgear must be fenced.
Advantages of outdoor switchgear compared to indoor switchgear
1) smaller volume of construction work; since only site preparation, road construction, foundation construction and installation of supports are necessary;
2) significant savings building materials(steel, concrete);
3) lower capital costs;
4) shorter construction time;
5) good visibility;
6) ease of expansion and ease of replacing equipment with others with smaller or larger dimensions, as well as the ability to quickly dismantle old and install new equipment.
7) less danger 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 switching disconnectors and monitoring devices is carried out in the air in any weather ( low temperatures, bad weather);
2) large area of the structure;
3) exposure of devices to sudden changes in ambient temperature, their vulnerability to pollution, dust, etc., which complicates their operation and forces the use of devices of a special design (for outdoor installation), which are more expensive.
The cost of indoor switchgear is usually 10–25% higher than the cost of the corresponding outdoor switchgear.
Currently, in most cases, outdoor switchgear is used of the so-called low type, in which all devices are located in the same horizontal plane and installed on special bases, relatively small height; prefabricated busbars are mounted on supports that are also of relatively low height.
4.1.24. Switchgears installed in rooms accessible to uninstructed personnel must have live parts covered with solid fences.
If a switchgear is used with open live 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 the non-insulated live parts of the device must be at least 0.7 m, and from solid ones - in accordance with 4.1.14. The width of passages is taken in accordance with the requirements given in 4.1.21.
4.1.25. The termination of wires and cables must be done so that it is located inside the device.
4.1.26. Removable barriers must be strengthened so that their removal is impossible without the use of tools. The doors must be locked with a key.
4.1.27. The installation of complete switchgears and substations (switchgear switchgear, package transformer substations) must comply with the requirements given in Chapter. 4.2 for switchgear and package substation above 1 kV.
Installation of switchgear outdoors
4.1.28. When installing switchgear 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 be designed in accordance with environmental conditions. In areas where snow drifts of 1 m or more in height are observed, cabinets should be installed on elevated foundations.
2. Local heating must be provided in the cabinets to ensure normal operation of devices, relays, measuring instruments and metering devices in accordance with GOST requirements.
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 alternating current substations with voltages above 1 kV. The rules do not apply to special switchgear and substations regulated by special technical specifications, and for mobile electrical installations.
4.2.2. A switchgear is an electrical installation that serves to receive and distribute electricity and contains switching devices, busbars and connecting busbars, auxiliary devices (compressor, battery, etc.), as well as protection devices, automation and measuring instruments.
An open switchgear (OSD) is a switchgear, all or the main equipment of which is located in the open air.
A closed switchgear is called 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 intended for outdoor installation is abbreviated as KRUN.
4.2.4. A substation is an electrical installation used for the conversion and distribution of electricity and consisting of transformers or other energy converters, switchgear, 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 RU) is a substation (RU) 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 intra-shop substation is a substation located inside a production building (open or in a separate enclosed room).
4.2.8. A complete transformer (converter) substation is a substation consisting of transformers (converters) and units (switchgear or switchgear and other elements) supplied assembled or fully prepared for assembly. Complete transformer (converter) substations (KTP, KPP) or parts of them installed indoors are classified as indoor installations; those installed outdoors are classified as outdoor installations.
4.2.9. A pole (mast) transformer substation is an open transformer substation, all of whose equipment 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 intended for receiving and distributing electricity at one voltage without conversion and transformation, which is not part of the substation.
4.2.11. A chamber is a room intended for the installation of devices and tires.
A closed cell is a cell 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-solid (mesh or mixed) fences.
Mixed fencing refers to fencing made from mesh and solid sheets.
An explosion chamber is a closed chamber designed to localize possible emergency consequences of damage to the devices installed in it and having access to the outside or into the blast corridor.
4.2.12. A service corridor is a corridor along the switchgear chambers or cabinets, intended for servicing devices and buses.
An explosive corridor is a corridor into which the doors of the explosive chambers open.
Chapter 2.2. SWITCHGEARS AND SUBSTATIONS
2.2.1. This chapter applies to switchgear and substations of Consumers with voltages of 0.4 to 220 kV.
2.2.2. The Consumer switchgear room adjacent to premises owned by third parties and containing live equipment must be isolated from them. It must have a separate, lockable exit.
The switchgear equipment, which is in the service of Consumers and used by the energy supplying organization, must be controlled on the basis of instructions agreed upon by the Consumer and the energy supplying organization.
2.2.3. In switchgear rooms, doors and windows must always be closed, and openings in partitions between devices containing oil must be sealed. All holes where the cable passes are sealed. To prevent the entry of animals and birds, all holes and openings in the external walls of the premises are sealed or closed with meshes with a mesh size of (1 × 1) cm.
2.2.4. Live parts of ballasts and protection devices must be protected from accidental contact. In special rooms (electrical machine rooms, switchboards, control stations, etc.), open installation of devices without protective covers is allowed.
All switchgear (boards, assemblies, etc.) installed outside electrical rooms must have locking devices that prevent non-electrical personnel from accessing them.
2.2.5. Electrical equipment of switchgear systems of all types and voltages must satisfy operating conditions both under normal conditions and during short circuits, overvoltages and overloads.
The insulation class of electrical equipment must correspond to the rated voltage of the network, and surge protection devices must correspond to the insulation level of electrical equipment.
2.2.6. When electrical equipment is located in an area with a polluted atmosphere, measures must be taken to ensure reliable insulation:
- in open switchgears (hereinafter referred to as open switchgears) - strengthening, washing, cleaning, coating with hydrophobic pastes;
- in closed switchgears (hereinafter referred to as closed switchgears) - protection against the penetration of dust and harmful gases;
- in complete outdoor switchgear - sealing cabinets and treating insulation with hydrophobic pastes.
2.2.7. Heating by induced current of structures located near live parts through which current flows and accessible to personnel should not exceed 50 degrees. WITH.
2.2.8. Air temperature inside the indoor switchgear in summer time should be no more than 40 degrees. C. If it increases, measures must be taken to reduce the temperature of the equipment or cool the air.
The air temperature in the compressor station room must be maintained within (10 - 35) degrees. WITH; in the premises of gas complete distribution devices (hereinafter referred to as GIS) - within (1 - 40) degrees. WITH.
The temperature of detachable busbar connections in the switchgear must be monitored according to an approved schedule.
2.2.9. The distances from live parts of the outdoor switchgear to trees and tall bushes must be such that the possibility of overlap is excluded.
2.2.10. The covering of floors in closed switchgear, switchgear and switchgear switchgear should be such that there is no formation of cement dust.
Premises intended for the installation of cells of a complete gas-insulated switchgear (hereinafter referred to as GIS), as well as for their inspection before installation and repair, must be isolated from the street and other premises. Walls, floors and ceilings must be painted with dust-proof paint.
Cleaning of premises should be done using wet or vacuum methods. The premises must be equipped supply and exhaust ventilation with air suction from below. The supply ventilation air must pass through filters that prevent dust from entering the room.
2.2.11. Cable channels and ground cable trays of outdoor switchgear and closed switchgear must be covered with fireproof slabs, and the places where cables exit from cable channels, trays, from floors and transitions between cable compartments must be sealed with fireproof material.
Tunnels, basements, canals must be kept clean and drainage devices ensure unhindered drainage of water.
Oil receivers, gravel bed, drains and oil outlets must be maintained in good condition.
2.2.12. The oil level in oil switches, instrument transformers and inputs must remain within the oil gauge scale at maximum and minimum temperatures ambient air.
The oil of leaking bushings must be protected from moisture and oxidation.
2.2.13. Roads for vehicle access to the switchgear and substations must be in good condition.
Places where vehicles are allowed to cross cable channels must be marked with a sign.
2.2.14. All keys, buttons and control handles must have inscriptions indicating the operation for which they are intended (“On”, “Off”, “Decrease”, “Add”, etc.).
Signal lamps and signaling devices must have inscriptions indicating the nature of the signal (“On”, “Off”, “Overheating”, etc.).
2.2.15. Switches and their drives must have indicators of the off and on positions.
On switches with a built-in drive or with a drive located in close proximity to the switch and not separated from it by a solid opaque fence (wall), it is allowed to install one indicator - on the switch or on the drive. On switches whose external contacts clearly indicate the on position, it is not necessary to have an indicator on the switch and the built-in or non-walled operator.
Drives of disconnectors, grounding knives, separators, short circuiters and other equipment separated from the devices by a wall must have indicators of the off and on positions.
All drives of disconnectors, separators, short circuiters, grounding knives that do not have guards must have devices for locking them in both the on and off positions.
Switchgears equipped with switches with spring drives must be equipped with devices for winding the spring mechanism.
2.2.16. Personnel servicing the reactor plant must have documentation on acceptable operating modes under normal and emergency conditions.
The duty personnel must have a supply of calibrated fuse links. The use of uncalibrated fusible inserts is not permitted. Fuse links must match the type of fuse.
The serviceability of reserve elements of the switchgear (transformers, switches, busbars, etc.) must be regularly checked by switching on voltage within the time limits established by local instructions.
2.2.17. RU equipment must be periodically cleaned of dust and dirt.
The cleaning time is determined by the person responsible for electrical equipment, taking into account local conditions.
Cleaning of switchgear premises and electrical equipment must be carried out by trained personnel in compliance with safety rules.
2.2.18. Locking devices of distribution devices, except mechanical ones, must be permanently sealed. Personnel performing switching operations are not allowed to unlock these devices without authorization.
2.2.19. To apply grounding in switchgear with voltages above 1000 V, as a rule, stationary grounding blades should be used.
The handles of the grounding knife drives should be painted red, and the grounding knife drives, as a rule, should be painted black. Operations with manual drives devices must be manufactured in compliance with safety regulations.
In the absence of stationary grounding blades, places for connecting portable grounding connections to live parts and the grounding device must be prepared and marked.
2.2.20. Inscriptions indicating the purpose of the connections and their dispatch name must be made on the doors and inner walls of switchgear switchgear chambers, outdoor switchgear equipment, front and inner parts of outdoor and indoor switchgear, assemblies, as well as on the front and back sides of the switchboard panels.
There must be warning posters and signs of the established type on the doors of the switchgear.
On safety panels and (or) connection fuses there must be inscriptions indicating the rated current of the fuse link.
2.2.21. The switchgear must contain electrical protective equipment and personal protection(in accordance with the standards for equipping with protective equipment), fire protection and aids(sand, fire extinguishers) and first aid supplies for accident victims.
For RUs served by operational mobile teams (hereinafter referred to as OVB), protective equipment may be located at the OVB.
2.2.22. Cabinets with equipment for relay protection and automation devices, communications and telemechanics, control cabinets and distribution cabinets of air circuit breakers, as well as cabinets for drives of oil circuit breakers, separators, short circuiters and motor drives of disconnectors installed in switchgear, in which the air temperature may be below the permissible value, must have electric heating devices.
Switching on and off of electric heaters should, as a rule, be carried out automatically. The system for automatically turning on and off electric heaters must also provide for constant monitoring of their integrity with the transfer of information to the local control panel and (or) dispatch console.
Oil switches must be equipped with electrical heating devices for the bottoms of tanks and housings, which are switched on when the ambient temperature drops below the permissible level. The temperature values at which electric heaters must be put into operation and decommissioned are established by local instructions, taking into account the instructions of the electrical equipment manufacturers.
2.2.23. Reservoirs of air switches and other devices, as well as air collectors and cylinders must meet the established requirements.
2.2.24. The hinge joints, bearings and rubbing surfaces of the mechanisms of switches, disconnectors, separators, short circuiters and their drives must be lubricated with low-freezing lubricants, and the oil dampers of switches and other devices must be filled with oil, the freezing point of which must be at least 20 degrees. Below the minimum winter outdoor temperature.
2.2.25. Automatic control, protection and alarm devices of the air treatment unit, as well as safety valves, must be systematically checked and adjusted in accordance with the requirements of the manufacturer's instructions.
2.2.26. The time between stopping and subsequent starting of working compressors (non-working pause) must be at least 60 minutes. for compressors with operating pressure 4.0 - 4.5 MPa (40 - 45 kgf/cm2) and at least 90 min. for compressors with a working pressure of 23 MPa (230 kgf/cm2).
Replenishment of air flow by working compressors should be ensured in no more than 30 minutes. for compressors with operating pressure (4.0 - 4.5) MPa (40 - 45) kgf/cm2 and 90 min. for compressors with a working pressure of 23 MPa (230 kgf/cm2).
2.2.27. Drying compressed air for switching devices must be carried out thermodynamically.
The required degree of drying of compressed air is ensured when the difference between the nominal compressor and nominal operating pressure of the switching devices is at least two - for devices with a nominal operating pressure of 2 MPa (20 kgf/cm2) and at least four - for devices with a nominal operating pressure (2.6 - 4.0) MPa (26 - 40 kgf/cm2).
2.2.28. Moisture from air collectors with compressor pressure (4.0 - 4.5) MPa (40 - 45) kgf/cm2 must be removed at least once every 3 days, and at facilities without permanent duty personnel - according to an approved schedule drawn up on the basis operating experience.
The bottoms of the air collectors and the drain valve must be insulated and equipped with an electric heating device, which is turned on when moisture is removed for the time required for ice to melt at subzero outside temperatures.
Removal of moisture from condensate collectors of groups of cylinders with a pressure of 23 MPa (230 kgf/cm2) must be carried out automatically every time the compressor is started. To avoid freezing of moisture, the lower parts of the cylinders and condensate collectors must be placed in a heat-insulating chamber with an electric heater, with the exception of cylinders installed after the compressed air purification units (hereinafter referred to as the CAP). The BOV water separator must be purged at least 3 times a day.
Checking the degree of drying - the dew point of the air at the outlet of the water treatment plant should be carried out once a day. The dew point should not be higher than minus 50 degrees. C at positive ambient temperature and not higher than minus 40 degrees. C - when negative.
2.2.29. Internal inspection and hydraulic testing of air collectors and compressor pressure cylinders must be carried out in accordance with established requirements. Internal inspection of tanks of air switches and other devices should be carried out during major repairs.
Hydraulic tests of air circuit breaker tanks must be carried out in cases where inspection reveals defects that cast doubt on the strength of the tanks.
The internal surfaces of the tanks must have an anti-corrosion coating.
2.2.30. Compressed air used in air switches and drives of other switching devices must be cleaned of mechanical impurities using filters installed in the distribution cabinets of each air switch or on the air duct supplying the drive of each device.
After completing the installation of the air preparation network, before the initial filling of the tanks of air switches and drives of other devices, all air ducts must be purged.
To prevent contamination of compressed air during operation, the following must be purged:
- main air ducts at positive ambient temperatures - at least once every 2 months;
- air ducts (separations from the network) to the distribution cabinet and from the cabinet to the reservoirs of each pole of switches and drives of other devices with their disconnection from the device - after each major overhaul of the device;
- tanks of air circuit breakers - after each major and current repairs, as well as in case of violation of the operating modes of compressor stations.
2.2.31. For air circuit breakers, the ventilation of the internal cavities of the insulators must be periodically checked (for circuit breakers with indicators).
The frequency of inspections should be established based on the recommendations of the manufacturers.
2.2.32. The humidity of SF6 gas in switchgear and gas-insulated circuit breakers must be monitored for the first time no later than a week after filling the equipment with SF6 gas, and then 2 times a year (in winter and summer).
2.2.33. Monitoring of SF6 gas concentration in switchgear and switchgear switchgear rooms should be carried out using special leak detectors at a height of 10 - 15 cm from the floor level.
The concentration of SF6 gas in the room must be within the limits specified in the instructions of the manufacturers of the devices.
Control must be carried out according to a schedule approved by the Consumer’s technical manager.
2.2.34. Leakage of SF6 gas should not exceed 3% of the total mass per year. It is necessary to take measures to fill tanks with SF6 gas when its pressure deviates from the nominal one.
Operations with switches under reduced SF6 gas pressure are not allowed.
2.2.35. Vacuum arc-extinguishing chambers (hereinafter referred to as VAC) must be tested in the volumes and time frames required established by instructions factories that manufacture switches.
When testing KDV with increased voltage with an amplitude value of over 20 kV, it is necessary to use a screen to protect against the resulting X-ray radiation.
2.2.36. Checking the extinguishing chambers of load switches, determining the degree of wear of gas-generating arc extinguishing liners and burning of fixed arc extinguishing contacts is carried out periodically within the time limits established by the person responsible for electrical equipment, depending on the frequency of operation of the load switches.
2.2.37. Draining moisture from the tanks of oil switches must be done 2 times a year - in the spring with the onset of positive temperatures and in the fall before the onset of negative temperatures.
2.2.38. Preventive inspections, measurements and tests of reactor plant equipment must be carried out in the scope and within the time limits provided for by the electrical equipment testing standards (Appendix 3).
2.2.39. Inspection of the reactor plant without shutdown should be carried out:
- at facilities with permanent staff duty - at least 1 time per 1 day; in the dark to identify discharges, corona - at least once a month;
- at facilities without permanent personnel duty - at least once a month, and at transformer and distribution points - at least once every 6 months.
In case of unfavorable weather (heavy fog, sleet, ice, etc.) or severe pollution at the outdoor switchgear, additional inspections must be organized.
All noticed malfunctions must be recorded in the log of defects and malfunctions on the equipment and, in addition, information about them must be reported to the person responsible for electrical equipment.
Noticed malfunctions must be corrected as soon as possible.
2.2.40. During inspection of the reactor plant Special attention the following should be addressed:
- condition of the premises, serviceability of doors and windows, absence of leaks in the roof and interfloor ceilings, presence and serviceability of locks;
- serviceability of heating and ventilation, lighting and grounding network;
- availability of fire extinguishing means;
- availability of tested protective equipment;
- availability of a first aid kit;
- oil level and temperature, no leaks in the devices;
- condition of contacts, switches of the low voltage switchboard;
- integrity of seals on meters;
- insulation condition (dustiness, presence of cracks, discharges, etc.);
- absence of damage and traces of corrosion, vibration and crackling in SF6 equipment;
- operation of the alarm system;
- air pressure in tanks of air circuit breakers;
- compressed air pressure in the reservoirs of pneumatic drives of switches;
- no air leaks;
- serviceability and correctness of indications of switch position indicators;
- the presence of ventilation of the poles of air circuit breakers;
- no oil leakage from capacitors of capacitive voltage dividers of air circuit breakers;
- operation of electric heating devices in the cold season;
- closure density of control cabinets;
- possibility of easy access to switching devices, etc.
2.2.41. Major repairs of reactor plant equipment must be carried out within the following time limits:
- oil switches - once every 6 - 8 years when monitoring the characteristics of the switch with a drive during the overhaul period;
- load switches, disconnectors and grounding knives - once every 4 - 8 years (depending on design features);
- air switches - once every 4 - 6 years;
- separators and short-circuiters with an open knife and their drives - once every 2 - 3 years;
- compressors - once every 2 - 3 years;
- GIS - once every 10 - 12 years;
- SF6 and vacuum circuit breakers - once every 10 years;
- conductors - once every 8 years;
- all devices and compressors - after exhaustion of their service life, regardless of the duration of operation.
First major renovation installed equipment must be carried out within the time limits specified in the technical documentation of the manufacturer.
Indoor disconnect switches should be repaired as needed.
Repair of reactor plant equipment is also carried out as necessary, taking into account the results of preventive tests and inspections.
The frequency of repairs can be changed, based on operating experience, by the decision of the technical manager of the Consumer.
Extraordinary repairs are carried out in the event of equipment failures, as well as after the switching or mechanical resource has been exhausted.
Distribution device (RU) They call an electrical installation that serves to receive and distribute electricity and contains switching devices, busbars and connecting buses, auxiliary devices (compressor, battery, etc.), as well as protection devices, automation and measuring instruments.
Switchgear of electrical installations are designed to receive and distribute electricity of one voltage for further transmission to consumers, as well as to power equipment within the electrical installation.
If all or the main equipment of a switchgear is located in the open air, it is called open (OSU): if it is located in a building, it is called closed (ZRU). A switchgear consisting of fully or partially closed cabinets and blocks with built-in devices, protection and automation devices, supplied assembled or fully prepared for assembly, is called complete and is designated for internal installation of switchgear, for external installation - KRUN.
Power center - a generator voltage distribution device or a secondary voltage distribution device of a step-down substation, to which the distribution networks of a given area are connected.
Switchgears (SD) are classified according to several criteria; below we present their types and design features.
Switchgears up to 1000 V
Switchgears up to 1000 V are made, as a rule, indoors in special cabinets (panelboards). Depending on the purpose, 220/380 V switchgears (voltage class 0.4 kV) can be designed to power consumers or exclusively for the electrical installation’s own needs.
Structurally switchgears 0.4 kV have protective devices (circuit breakers, fuses), switches, switch-disconnectors and busbars connecting them, as well as terminal blocks for connecting consumer cable lines.
In addition to power circuits, a number of additional devices and auxiliary circuits can be installed in low-voltage switchboards, namely:
electricity meters and current transformers;
circuits for indicating and signaling the position of switching devices;
measuring instruments for monitoring voltage and current in various points switchgear;
signaling and ground fault protection devices (for IT configuration networks);
automatic reserve input devices;
remote control circuits for switching devices with motor drives.
Low-voltage switchgears can also include switchboards direct current, distributing direct current from converters, batteries for power supply of operational circuits of electrical equipment and relay protection and automation devices.
High voltage switchgears
Switchgears of voltage class above 1000 V can be designed both outdoors - open type (OSU), and indoors – closed type(ZRU).
Equipment is placed in closed switchgears in prefabricated chambers for one-way service of KSO either in complete switchgears type KRU.
Cameras of the KSO type are more preferable for rooms of limited area, since they can be installed close to the wall or with their back walls facing each other. KSO cameras have several compartments closed with mesh fences or solid doors.
CSOs are equipped with various equipment, depending on their purpose. To power the outgoing lines, a high-voltage switch, two disconnectors (on the busbar side and on the line side), current transformers are installed in the chamber; on the front side there are disconnector control levers, a switch drive, as well as low-voltage circuits and protection devices implemented to protect and control this line.
Cameras of this type can be equipped with voltage transformers, arresters (overvoltage limiters), and fuses.
Switchgear type KRU are a cabinet divided into several compartments: current transformers and outgoing cables, busbars, a withdrawable part and a compartment secondary circuits.
Each compartment is isolated from each other to ensure safety during maintenance and operation of switchgear cabinet equipment. The withdrawable part of the cabinet, depending on the purpose of the connection, can be equipped with a circuit breaker, a voltage transformer, arresters (arresters), and an auxiliary transformer.
The retractable element relative to the cabinet body can occupy a working, control (disconnected) or repair position. In the operating position the main and auxiliary circuits are closed, in the control position the main circuits are open and the auxiliary circuits are closed (in the disconnected position the latter are open), in the repair position the retractable element is located outside the cabinet body and its main and auxiliary circuits are open. The force required to move the retractable element should not exceed 490 N (50 kgf). When the retractable element is rolled out, the openings to the fixed detachable contacts of the main circuit are automatically closed with curtains.
The current-carrying parts of switchgear are made, as a rule, with busbars made of aluminum or its alloys; at high currents it is permissible to use copper busbars, at rated currents up to 200 A - steel busbars. Installation of auxiliary circuits is carried out with insulated copper wire with a cross-section of at least 1.5 square meters. mm, connection to meters - with a wire with a cross-section of 2.5 sq. mm, solder joints - at least 0.5 sq. mm. Connections subject to bending and torsion are usually made with stranded wires.
Flexible connection of the auxiliary circuits of the stationary part of the switchgear with the retractable element is carried out using plug connectors.
Switchgear cabinets, as well as grounding blades, must meet the requirements for electrodynamic and thermal resistance to through short-circuit currents. To ensure the requirements for mechanical resistance, the number of cycles that switchgear cabinets and its elements must withstand is regulated: detachable contacts of the main and auxiliary circuits, a retractable element, doors, and a grounding switch. The number of cycles of switching on and off the built-in component equipment (switches, disconnectors, etc.) is accepted in accordance with the PUE.
To ensure safety, switchgear cabinets are equipped with a number of interlocks. After rolling out the retractable element, all current-carrying parts of the main circuits that may be energized are covered with protective curtains. These curtains and barriers must not be removed or opened without the use of keys or special tools.
In stationary switchgear cabinets, it is possible to install stationary or inventory partitions to separate live parts of equipment. It is not allowed to use bolts, screws, or studs that act as fasteners for grounding. In grounding areas there must be an inscription “earth” or a grounding sign.
The type of switchgear cabinet is determined by the circuit diagram of the switchgear main circuit. The main electrical device that determines the design of the cabinet is the switch: low-oil, electromagnetic, vacuum and SF6 switches are used. Secondary circuit designs are extremely diverse and have not yet been completely unified.
Complete devices may have different design, for example, with gas insulation - GIS or intended for outdoor installation - KRUN, which can be installed outdoors.
Open-type switchgears provide for the installation of electrical equipment on metal structures, on concrete foundations, without additional protection from external influences. Auxiliary circuits of outdoor switchgear equipment are mounted in special cabinets that are protected from mechanical influences and moisture.
Switchgears, both closed and open types, are classified according to several criteria, depending on their design (scheme).
The first criterion is the method of performing partitioning. There are switchgears with busbar sections and busbar systems. Bus sections provide power to each individual consumer from one section, and bus systems allow one consumer to be switched between several sections. Bus sections are connected by sectional switches, and bus systems are connected by bus connectors. These switches allow sections (systems) to be powered from each other in the event of a loss of power in one of the sections (systems).
The second criterion is the presence of bypass devices– one or more bypass bus systems that allow equipment elements to be removed for repair without the need to de-energize consumers.
The third criterion is the equipment power supply circuit (for open switchgear). IN in this case There are two possible scheme options - radial and ring. The first scheme is simplified and provides for power supply to consumers through one switch and disconnectors from the busbars. In a ring circuit, each consumer is powered by two or three switches. Ring circuit more reliable and practical in terms of equipment maintenance and operation.
Closed switchgear (SGD)
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 placing an outdoor switchgear, when located at enterprises in cramped conditions, in areas with polluted air, which has a destructive effect on open live 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. In this case, the 110 kV closed switchgear is constructed using equipment intended for outdoor switchgear.
Closed reactor plants are located in one-, two-, or three-story buildings made of standardized prefabricated reinforced concrete structures. Closed 6 and 10 kV switchgear and substations are located in built-in, attached or free-standing buildings made of brick or precast reinforced concrete, built on foundations of reinforced concrete blocks.
Closed 35 and 110 kV switchgears are located in separate buildings made of precast reinforced concrete. The dimensions of the premises depend on the type of electrical equipment used, the layout of the main circuits, the filling pattern and the permissible dimensions of the width of corridors and passages in indoor switchgear, transformer chambers and switchboard rooms (Table 4). When laying out switchgear and substations, the current building standards and dimensions of typical precast concrete elements are taken into account: reinforced concrete slabs, beams, roofing and interfloor coverings.
When designing indoor switchgear and substations premises, the requirements of the electrical installation regulations are taken into account, the main ones 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 are usually located separately. Depending on the length of the switchgear room, one (for a length of up to 7 m) or two exits (for a length of over 7 and up to 60 m) are installed, located at its ends (it is allowed to place exits from the switchgear at a distance of up to 7 m from its ends).
Doors from switchgear open in the direction of other rooms, outwards or towards switchgear with low voltage, and have self-locking locks that open with inside rooms without a key. The installation of thresholds in doors is not allowed.
Complete devices are most widely used during the installation of modern indoor switchgear and 6 and 10 kV substations. 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 designs with main circuit devices installed in chambers and cabinets, with protection, measurement, metering and alarm devices, with full busbar and secondary circuit wiring within the chambers.
Open switchgear (OSD)
Oil switch in outdoor switchgear
An open switchgear (OSD) is a switchgear whose equipment is located in the open air. All elements of the outdoor switchgear are placed on concrete or metal bases. The distances between elements are selected according to the PUE. At voltages of 110 kV and higher, oil receivers - gravel-filled recesses - are created under devices that use oil for operation (oil transformers, switches, reactors). This measure is aimed at reducing the likelihood of a fire and reducing damage in the event of an accident on such devices.
Outdoor switchgear busbars 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 hanging insulators.
The territory on which the outdoor switchgear is located must be fenced.
Advantages
§ Outdoor switchgear allows the use of arbitrarily large electrical devices, which, in fact, explains their use at high voltage classes.
§ Manufacturing 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
§ Visual observation of all outdoor switchgear devices is possible
Flaws
§ Operation of outdoor switchgear is difficult in unfavorable conditions weather conditions, Besides, environment has a stronger effect on the outdoor switchgear elements, which leads to their early wear.
§ Outdoor switchgear takes up much more space than indoor switchgear.
Complete switchgear (KRU) is a switchgear assembled from standard standardized blocks (so-called cells) of a high degree of readiness, assembled in a factory. At voltages up to 35 kV, cells are manufactured 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 complex design, externally similar to 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). Switchgears are widely used in cases where compact placement of the switchgear is necessary. In particular, switchgear is used at power stations, city substations, to power oil industry facilities (oil pipelines, drilling rigs), and in ship energy consumption circuits.
A switchgear in which all devices are located in one compartment is called a one-way service chamber (SOC). As a rule, the CSO is truly one-way service, most often has open busbars, back wall absent.
Switchgear 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: relay protection and automation devices, switches, circuit breakers. On the door of the relay compartment, as a rule, there are light-signal fittings, electricity metering and measurement devices, and cell control elements.
§ The switch compartment (4) contains a power switch or other high-voltage equipment (disconnect contacts, fuses, voltage transformers). Most often in switchgear, this equipment is placed on a withdrawable or retractable element.
§ In the busbar compartment (6) there are power busbars (8) connecting the cabinets of the switchgear section.
§ The input compartment (5) is used to accommodate cable termination, measuring current transformers (7), voltage transformers, surge arresters.
RU up to 1000V.
The main type of switchgear with voltages up to 1000 V are switchboards. They help provide nutrition external loads and own needs of substations. Distribution boards varied in design and in the devices and devices installed in them. Panels are assembled from panels or cabinets interconnected in quantities and combinations corresponding to the design scheme and the construction part of the panel room. The panel (or cabinet) is a completely finished element of the switchboard, and the switchboard 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, measuring and protection are installed. The panels of the switchboard are connected by busbars and secondary circuit wiring, to which the equipment mounted on the panels is connected. They are divided into inlet, linear and sectional depending on the purpose of the devices installed on them, as well as end ones, the purpose of which is the protective and decorative covering 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 2-3 mm thick with steel parts bent profiles for mounting devices and the same design: two front posts, an upper front sheet for measuring instruments, doors for servicing devices installed on the frame inside, two rear posts, transverse and longitudinal connections. Handles of drives of automatic machines and switches through rectangular holes panels displayed on the façade.
Installation of panels begins with marking the installation location of the foundation frame, which must be installed at the first stage of installation work. The passages between the wall and the shield, the symmetrical arrangement of the longitudinal and transverse axes of the shield to the switchboard room, the interface with cable ducts and openings, taking into account the level of the finished floor, are checked.
The panels are installed after completion of construction and finishing works on the foundation frame, aligned horizontally and vertical planes and temporarily fixed. After installation, connecting the blocks or panels together and alignment, the shield is finally secured with bolts or welding. They install busbars and install devices that arrive in separate packaging.
