Transformer substation high voltage switchgear. Types of devices for receiving and distributing electricity. Enclosed switchgears and substations

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REQUIREMENTS FOR DISTRIBUTION DEVICES AND TASKS OF THEIR MAINTENANCE

Switchgear units (RU) of substations are complexes of structures and equipment designed for receiving and distributing electrical energy.
Switchgears can be open (OSU) or closed (ZRU). Complete switchgears (KRU) for installation indoors and directly outdoors (KRUN) have become widespread. They are manufactured in stationary and roll-out versions, and are supplied assembled or fully prepared for assembly. Sealed switchgears that use SF6 gas as an insulating and arc-extinguishing medium are called switchgear.

TO The following requirements apply to switchgear equipment::

1. According to its nominal data, the switchgear equipment must satisfy operating conditions both in normal mode and during short circuit. Under normal operating conditions, heating of conductors by current should not exceed the values ​​​​established by the standards. This ensures reliable operation of live parts and guarantees an economically justified service life of the insulation, excluding its accelerated thermal aging. In short circuit mode, the switchgear equipment must have the necessary thermal and electrodynamic resistance.
2. The insulation of the equipment must correspond to the rated voltage of the network and withstand possible voltage increases during switching and atmospheric overvoltages. One of the main conditions for reliable operation of insulating structures is keeping the insulation clean - systematic cleaning, washing, coatings with hydrophobic pastes; for closed switchgear - protection against penetration of dust and harmful gases into the premises; in KRUN - sealing cabinets, coating insulation with hydrophobic pastes.
3. The equipment must operate reliably under permissible overloads, which should not lead to damage and a reduction in its service life.
4. The production premises of the reactor plant must be convenient and safe when servicing equipment by personnel. Switchgear switchgears with voltages of 400 kV and higher must be equipped with biological protection means in the form of stationary, portable or inventory screens, and personal protective equipment - shielding suits. Heating of structures located near live parts accessible to personnel should not exceed 50°C.
5. The temperature and air humidity in the indoor switchgear must be maintained such that dew does not occur on the insulators; the temperature in summer should not exceed 40°C. Ventilation openings should have louvers or metal mesh. Windows in the closed switchgear must be locked or protected with nets, and openings and openings in walls or cells must be sealed to prevent the possibility of animals entering. birds. The roof must be in good condition. Floor coverings must not allow the formation of cement dust.
6. The switchgear must be equipped with working and emergency electric lighting. Lighting equipment must be installed in such a way as to ensure safe operation.
7. For personnel orientation, all equipment and especially switching device drives must be provided with clear, conspicuous inscriptions indicating the name of the equipment and the dispatcher name of the electrical circuit to which the inscription refers. In the switchgear, an atypical arrangement of the drive handles of bus disconnectors is unacceptable, when, for example, some disconnectors are turned off by moving the drive handle down, others - up. Switches and their drives, disconnectors, separators, short-circuiters and stationary grounding switches must have “On” and “Off” position indicators. Switchgears must be equipped with an interlock that prevents the possibility of erroneous operations with disconnectors, grounding blades, and short circuiters. Locking devices, except mechanical ones, must be permanently sealed.
8. The RU premises must contain safety equipment and fire extinguishing equipment.

The tasks of maintaining the reactor plant are:

1. ensuring compliance of the operating modes of the switchgear and individual electrical circuits with the technical characteristics of the installed equipment;
2. maintaining at each period of time such a scheme of switchgear and substations so that they best meet the requirements of reliable operation of the power system and trouble-free selective operation of relay protection and automation devices;
3. systematic supervision and care of the equipment and premises of the reactor plant, elimination as soon as possible of identified malfunctions and defects, since their development may lead to operational failures and accidents;
4. control over the timely implementation of preventive tests and equipment repairs;
5. compliance with the established order and sequence of switching operations in the switchgear.

Inspection of the reactor plant without shutting down the equipment should be carried out:

1. at facilities with constant personnel duty - at least once every 3 days, in addition, in the dark to detect the presence of discharges, corona - at least once a month;
2. at facilities without permanent duty - at least once a month, and at transformer and distribution points - at least once every 6 months.
3. after switching off the short circuit.

In case of unfavorable weather (heavy fog, sleet, ice) or increased contamination of the outdoor switchgear, additional inspections are required. During inspection, it is strictly prohibited to perform any work on the equipment.
During inspections of the reactor plant, all comments are recorded in a log of defects and malfunctions and brought to the attention of the managers of the energy enterprise, who take appropriate measures to eliminate the identified violations as soon as possible.
RUs with voltages above 1000 V are operated in accordance with the “Rules for the technical operation of power plants and networks.”
Tests of the electrical equipment of the reactor plant should usually be carried out during periods of its repair.
Routine repairs of the electrical equipment of the reactor plant, as well as checking its operation (testing), must be carried out in accordance with the schedule approved by the chief engineer of the power enterprise, with the exception of unforeseen emergency and other urgent work that is carried out outside the schedule with its own procedure for registering these works.

The electrical energy generated by the stations is supplied to the point of consumption through a system of interconnected transmission, distribution and conversion electrical installations. Electricity is transmitted via overhead power lines with voltages ranging from several hundred to hundreds of thousands of volts. Electrical energy is transmitted through system overhead networks with voltages of 35, 110, 150, 220 kV and higher on the rated voltage scale.

Installations used for receiving and distributing electricity are called switchgears (RU). They contain switching devices, busbars and connecting buses, auxiliary devices (compressor, battery and others), as well as protection, automation devices, etc. RUs include power centers (CP), distribution points (RP), distribution lines (RL).

The power center is the generator voltage switchgear of a power plant or the secondary voltage switchgear of a step-down substation of a power system with a regulation system, to which the distribution networks of a particular area are connected.

A distribution point is a substation of an industrial enterprise or city electrical network, designed to receive and distribute electricity with one voltage without converting it.

A distribution line is a line that supplies a number of transformer substations from the CPU or RP, as well as large electrical installations.

Switchgears can be open (open switchgear - all or main equipment is located in the open air) and closed (closed switchgear - equipment is located in the building). Particular attention should be paid to the most common complete switchgear (SGD), consisting of fully or partially closed cabinets or blocks with built-in devices, protection and automation devices, supplied assembled or fully prepared for assembly and produced for both internal and external use. outdoor installation.

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.
The substation at which the alternating current voltage is converted using a transformer is called a transformer station (TP). If the alternating current voltage at a transformer transformer is converted to a lower voltage, it is called a step-down, and if it is converted to a higher voltage, it is called a step-up.

At transformer substations, transformers are installed that serve to change the voltage. Simultaneously with the voltage transformation, the number of lines usually changes. For example, one or two high voltage lines approach a transformer substation, and several low voltage lines depart from it.

There are two types of transformer substations: open, in which the main equipment is located in open areas, and closed, in which the equipment is located in premises.
If voltage transformation is not performed at a substation, but only the number of lines changes, then it is called distribution.

Converter substations are used to rectify alternating current or convert direct current into alternating current. At all substations, devices for switching electrical networks and various control and measuring instruments are installed.

Electrical networks are divided by voltage into low voltage networks - up to 1 kV - and high voltage networks - more than 1 kV.

Most industrial enterprises receive electricity from substations. At substations, two or more transformers are installed, through which energy from the power system is transmitted via high voltage lines (35, 110 or 220 kV) to sectional operating (or backup) buses with a voltage of 6-10 kV.

A substation fed directly from the energy system (or a factory power plant) is called the main step-down substation (MSS) of the enterprise, and a substation at which the voltage is reduced directly to power the electrical receivers of one or more workshops is called a workshop transformer substation (TS).

Transformer and converter substations, as well as distribution devices, are supplied complete (KTP, KPP) assembled or fully prepared for assembly.
Measurement of current and voltage on the buses of distribution devices and in electrical circuits is carried out using current transformers or voltage transformers, which serve to reduce the current or voltage of the primary circuits of alternating current electrical installations, as well as to power the coils of measuring instruments, relay protection and automation devices connected to them secondary windings.

The use of instrument transformers allows:

• measure any voltages and currents using conventional measuring instruments with standard windings designed for a voltage of 100 V and a current of 5 A;
• separate measuring instruments and relays from voltages above 380 V, ensuring the safety of their maintenance.

The primary winding of the measuring transformer is under the influence of the measured value, and the secondary winding is closed to measuring instruments and protection devices.

Touching measuring instruments directly connected to the high voltage circuit is dangerous for humans, therefore, in this case, measuring instruments and automatic protection equipment (relays) are connected to the secondary circuit of instrument transformers, connected to the high voltage circuit only through the magnetic flux in the core. In addition, instrument transformers serve to expand the measurement limits of AC devices, like additional resistors and shunts. The use of instrument transformers with different transformation ratios allows the use of devices with standard measurement limits (100 V and 5 A) when determining a wide variety of voltages and currents.

There are two types of instrument transformers: voltage transformers and current transformers.

Voltage transformers power the voltage windings of measuring instruments and relays (voltmeters, frequency meters, meters, wattmeters, voltage relays, power relays, etc.) in installations with voltages of 380 V and higher.

Current transformers power the current windings of measuring instruments and relays (ammeters, meters, wattmeters, current, power relays, etc.).

Most industrial enterprises source their electricity from utility systems, but some enterprises obtain their energy from their own factory power plants. The generation and distribution of energy within the enterprise from its own power plants is carried out mainly in generator mode with voltages of 6 and 10 kV.

Electrical circuits of distribution devices and substations can be primary and secondary.
Primary circuits include busbar devices and current-carrying parts of devices connected in a certain sequence.

Secondary circuits include circuits with the help of which electrical measurements, relay protection, alarms, remote control and automation are carried out in the primary circuits of switchgear substations, i.e. Secondary circuits provide control, protection, convenient and safe maintenance of primary circuits.
Schematic diagrams of primary circuits show all the main elements of an electrical installation: busbar devices, disconnectors, circuit breakers, fuses, transformers, reactors, etc., as well as connections between them. In order to better imagine the operation of the installation and its individual sections, primary diagrams usually show the main devices and devices of secondary circuits, measuring instruments, relay protection and automation devices without electrical connections. Modern switchgears may have different connection schemes.

It must be remembered that disconnecting a load-free line is associated with a break in its charging current, which is greater the longer the line.

A load switch installed instead of a disconnector allows you to turn off and turn on the line when the load is within the rated limit.

In this case, measuring current transformers are installed at the connection, and line and bus disconnectors are used to relieve voltage from the switch and current transformers during inspection, repair, testing and other work. Since operations with disconnectors are only possible when the switch is open, which breaks the current circuit, the order of disconnecting the line is as follows: first disconnect the switch, then the line disconnector and, finally, the bus disconnector. The order of switching on the line is reversed. This option for connecting to the switchgear is used for lines with heavy loads and high short-circuit current.

Typically, this scheme is used to connect overhead lines. In this case, grounding blades serve to ground and short-circuit the line after disconnection, since electrical charges induced by atmospheric electricity or nearby lines may arise in the disconnected line. The arresters are designed to discharge electrical charges of atmospheric electricity into the ground, creating significant overvoltages in the switched-on line that are dangerous for the entire installation.

In open switchgears, arresters are connected directly to the main busbars.
To disconnect this transformer from the network, use a bus disconnector (disconnection should only be done when the transformer is idle); High and low voltage protection is provided by fuses.

This circuit includes a switch designed for operational switching and relay protection (RP), the devices of which are powered by measuring current transformers.
The use of complete switchgears and transformer substations makes it possible to reduce installation time, reduce their cost and improve quality.

Distribution devices (RU) are electrical installations that serve to receive and distribute electricity and contain switching devices, busbars and connecting busbars, auxiliary devices (compressor, battery, etc.), as well as protection devices, automation and measuring instruments.
There are open devices - outdoor switchgear (all or the main equipment is located in the open air) and closed ones - closed switchgear (equipment is located in the building). Particular attention should be paid to complete switchgears (SGD) as the most common. A complete switchgear is a device consisting of fully or partially closed cabinets or blocks with built-in devices, protection and automation devices and supplied assembled or fully prepared for assembly. Switchgear is made for both indoor and outdoor installation.
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. Substations are divided into transformer and converter ones depending on the predominance of one or another function.
The substation at which alternating current voltage is converted using a transformer is called a transformer station (TP). If the alternating current voltage at a transformer transformer is converted to a lower voltage, it is called a step-down, and if it is converted to a higher voltage, it is called a step-up.
A substation fed directly from the energy system (or a factory power plant) is called the main step-down substation (MSS) of the enterprise, and a substation at which electricity is converted into reduced voltage directly to power the electrical receivers of one or more workshops is called a workshop transformer substation (TS).
A point designed to receive and distribute electricity without converting it is called a distribution point (DP), and a distribution point that receives power directly from the energy system (or a factory power plant) is called a central distribution point (CDP).
Transformer and converter substations, as well as distribution devices, are manufactured and supplied complete (KTP, KPP), assembled or fully prepared for assembly.
The source of power supply for most industrial enterprises, as a rule, is energy systems. Only sometimes do enterprises receive energy from their own factory power plants. Electricity supply and energy distribution within the enterprise from its own power plants is carried out mainly at generator voltages of 6 and 10 kV.
Most enterprises are powered from regional substations that are part of the energy system, via high-voltage power lines through step-down transformers installed at consumer substations, through electricity reception and distribution points (GPP, TsRP, RP and TP), as close as possible to consumers.
The transmission and distribution diagram of electrical energy is shown in Fig. 1. It depends on the distance between the enterprise and the power source (power plant, high-voltage network of the power system), power consumption, territorial location of loads, reliability requirements, category of electrical receivers for uninterruptible power supply, as well as the number of receiving and distribution points at the enterprise.

Rice. 1. Scheme of transmission and distribution of electrical energy:
G1, G2 - generators, RP - distribution point

4.2.81. Indoor switchgears and substations can be located either in free-standing buildings or be built-in or attached. The extension of a substation to an existing building using the building wall as a substation wall is permitted provided that special measures are taken to prevent damage to the waterproofing of the joint during settlement of the attached substation. The specified settlement must also be taken into account when attaching equipment to an existing building wall.

For 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 35-220 kV indoor switchgears and in closed transformer chambers, stationary devices should be provided or the possibility of using mobile or inventory lifting devices to mechanize repair work and equipment maintenance.

In rooms with switchgear, a platform should be provided for repair and adjustment of withdrawable elements. The repair site must be equipped with facilities for testing switch drives and control systems.

4.2.83. Closed switchgears of different voltage classes, as a rule, should be placed in separate rooms. This requirement does not apply to transformer substations of 35 kV and below, as well as switchgear.

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.

The rooms of switchgear, transformers, converters, etc. must be separated from service and other auxiliary rooms (for exceptions, see Chapter 4.3, 5.1 and 7.5).

4.2.84. When assembling GIS in an indoor switchgear, service platforms must be provided at different levels if they are not supplied by the manufacturer.

4.2.85. Transformer rooms and indoor switchgear are not allowed to be placed:

1) under production premises with a wet technological process, under showers, bathtubs, etc.;

2) directly above and below the premises, in which, within the area occupied by the switchgear or transformer rooms, more than 50 people can be present at the same time. for a period of more than 1 hour. This requirement does not apply to transformer rooms with dry transformers or with non-flammable filling, as well as switchgear for industrial enterprises.

4.2.86. The clear distances between bare current-carrying parts of different phases, from bare live parts to grounded structures and fences, floor and ground, as well as between bare current-carrying parts of different circuits must be no less than the values ​​given in Table. 4.2.7 (Fig. 4.2.14-4.2.17).

Flexible busbars in closed switchgear should be checked for their convergence under the influence of short-circuit currents in accordance with the requirements of 4.2.56.

4.2.87. The distances 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 AND according to table 4.2.7 (see Fig. 4.2.16).

4.2.88. Non-insulated live parts must be protected from accidental touches (placed in chambers, fenced with nets, etc.).

When placing non-insulated live parts outside the chambers and positioning them below the size D according to table 4.2.7 they must be protected from the floor. The height of the passage under the fence must be at least 1.9 m (Fig. 4.2.17).

Live parts located above the fences up to a height of 2.3 m from the floor must be located from the plane of the fence at the distances given in Table. 4.2.7 for size IN(see Fig. 4.2.16).

Devices in which the lower edge of the porcelain (polymer material) of the insulators is located above the floor level at a height of 2.2 m or more are allowed not to be fenced if the above requirements are met.

The use of barriers in fenced cells is not permitted.

Rice. 4.2.14. The smallest clear distances between non-insulated current-carrying parts of different phases in an indoor switchgear and between them and grounded parts (according to Table 4.2.9)

Rice. 4.2.15. The shortest distances between non-insulated live parts in an indoor switchgear and solid fences (according to Table 4.2.9)

Rice. 4.2.16. The shortest distances from uninsulated live parts in the closed switchgear to mesh fences and between unfenced uninsulated live parts of different circuits (according to Table 4.2.9)

Rice. 4.2.17. The shortest distances from the floor to unfenced uninsulated

current-carrying parts and to the lower edge of the porcelain insulator and the height of the passage into the closed switchgear. The shortest distance from the ground to unfenced linear outputs from the closed switchgear

outside the territory of the outdoor switchgear and in the absence of transport passage under the outlets

4.2.89. Unguarded, uninsulated leading parts of various circuits located at a height exceeding the size D according to table 4.2.7 must be located at such a distance from one another that after disconnecting any circuit (for example, a bus section), its safe service is ensured in the presence of voltage in adjacent circuits. In particular, the distance between unprotected live 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 must ensure convenient maintenance of the installation and movement of equipment, and it must be at least (counting the clearance between the fences): 1 m - with one-sided arrangement of the equipment; 1.2 m - with double-sided equipment arrangement.

In the service corridor, where the drives of 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 may be reduced to 1.8 m.

Table 4.2.7

The shortest clear distances from live parts to various elements of the switchgear

(substations) 3-330 kV, protected by arresters, and indoor switchgear 110-330 kV, protected by surge suppressors 1 , (in the denominator) (Fig. 4.2.14-4.2.17)

1 Surge suppressors have a protective level of phase-to-ground switching overvoltages of 1.8 U f.

4.2.91. The width of the service corridor for switchgear with withdrawable elements and package transformer substations should ensure ease of control, movement and reversal of equipment and its repair.

When installing switchgear and package transformer substations in separate rooms, the width of the service corridor should be determined based on the following requirements:

for single-row installation - the length of the largest switchgear trolley (with all protruding parts) plus at least 0.6 m;

with double-row installation - the length of the largest switchgear trolley (with all protruding parts) plus at least 0.8 m.

If there is a corridor at the rear of the switchgear and package transformer substations for their inspection, its width must be at least 0.8 m; Individual local narrowings of no more than 0.2 m are allowed.

When installing switchgear and package transformer substations openly in production premises, the width of the free passage must be determined by the location of the production equipment, ensure the possibility of transporting the largest switchgear elements to the switchgear substations, and in any case it must be at least 1 m.

The height of the room must be no less than the height of the switchgear, package transformer substations, 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 room height is allowed if this ensures the convenience and safety of replacement, repair and adjustment of switchgear equipment, package transformer substations, busbar inputs and jumpers.

4.2.92. The calculated loads on the floors of premises along the path of transportation of electrical equipment must be taken into account the weight of the heaviest equipment (for example, a transformer), and the openings must correspond to their dimensions.

4.2.93. For overhead inputs into closed switchgear switchgears, package transformer substations and closed substations that do not cross passages 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 Fig. 4.2.17).

At shorter distances from the wire to the ground, in the corresponding area under the input, either fencing the area with a fence 1.6 m high or a horizontal fence under the input must be provided. In this case, the distance from the ground to the wire in the plane of the fence must be at least the size E.

For overhead leads 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 leads from the closed switchgear to the territory of the outdoor switchgear, the indicated distances should be taken according to the table. 4.2.5 for size G(see Fig. 4.2.6).

The distances between adjacent linear terminals of two circuits must be no less than the values ​​​​given in table. 4.2.3 for size D, if partitions are not provided between the terminals of adjacent circuits.

In case of unorganized drainage, canopies should be provided on the roof of the indoor switchgear building over the air inlets.

4.2.94. Exits from the reactor plant should be carried out 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 must 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) if the length of the switchgear is more than 60 m, in addition to the exits at its ends, additional exits must 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 outside, to a staircase or to another industrial premises of category G or D, as well as to other compartments of the switchgear, separated from this one by a fire door of fire resistance class II. In multi-storey switchgears, a second and additional exits can also be provided to a balcony with an external fire escape.

Cell gates with a leaf width of more than 1.5 m must have a wicket if they are used for personnel exit.

4.2.95. It is recommended that the floors of the switchgear rooms be installed 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. The installation of thresholds in doors between separate rooms and in corridors is not allowed (for exceptions, see 4.2.100 and 4.2.103).

4.2.96. Doors from the switchgear must open towards other rooms or outwards and have self-locking locks that can be opened without a key from the switchgear side

Doors between compartments of one switchgear or between adjacent rooms of two switchgears must 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 switchgears of different voltages must open towards the switchgear with the lowest voltage.

Locks in the doors of switchgear rooms of the same voltage must be opened with the same key; keys to the entrance doors of the switchgear and other premises should not fit the locks of the cells, as well as the locks of doors in the fences of electrical equipment.

The requirement to use self-locking locks does not apply to switchgear of urban and rural distribution electrical networks with a voltage of 10 kV and below.

4.2.97. Enclosing structures and partitions of switchgear and package transformer substations for the power plant's own needs should be made of non-combustible materials.

It is allowed to install switchgear and package transformer substations for your own needs in process rooms 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 transformers with a power of each up to 0.63 MVA, 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 minutes, a height of at least height of the transformer, including high voltage bushings.

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, may be installed in fenced switchgear chambers. In this case, a threshold or ramp must be provided in the chamber, designed to hold the full volume of oil contained in the voltage transformer.

4.2.101. Switch cells should be separated from the service corridor by solid or mesh barriers, 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 switch with an oil mass of 60 kg or more in one pole, an oil receiver is required for the full volume of oil in one pole.

4.2.102. In closed, free-standing, attached and built-in substations, in the chambers of transformers and other oil-filled devices with an oil mass in one tank of up to 600 kg, when the chambers are located on the ground floor with doors facing outside, oil collecting devices are not installed.

When the mass of oil or non-flammable environmentally friendly dielectric in one tank is more than 600 kg, an oil receiver must be installed, designed to hold the full volume of oil, or to retain 20% of the oil with discharge to the oil sump.

4.2.103. When constructing chambers above the basement, on the second floor and above (see also 4.2.118), as well as when constructing an exit from the chambers into the corridor under transformers and other oil-filled devices, oil receivers must be constructed in one of the following ways:

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 an oil mass of 60 to 600 kg, an oil receiver designed to hold the full volume of oil is installed under the transformer (apparatus), or at the exit from the chamber there is a threshold or ramp to hold the full volume of oil;

3) with an oil weight of more than 600 kg:

an oil receiver containing at least 20% of the total volume of oil of the transformer or apparatus, with oil drainage into the oil sump. Oil drain pipes from oil receivers under transformers must have a diameter of at least 10 cm. On the side of the 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 drainage into 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 should be 5 cm below the grate. The top level of gravel in the oil 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 greater than the area of ​​the base of the transformer or apparatus.

4.2.104. Ventilation of transformer and reactor rooms must 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 permissible value for them.

Ventilation of transformer and reactor rooms must 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 with currents up to 1000 A, 20 °C for reactors with currents more than 1000 A.

If it is impossible to ensure heat exchange by natural ventilation, it is necessary to provide forced ventilation, and its operation must be monitored using alarm devices.

4.2.105. Supply and exhaust ventilation with intake at the floor level and at the level of the upper part of the room must be carried out in the room where the switchgear and SF6 gas cylinders are located.

4.2.106. RU 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 areas with low winter temperatures, supply and exhaust ventilation openings should be equipped with insulated valves that can be opened from the outside.

4.2.107. In rooms where on-duty personnel stay for 6 hours or more, the air temperature must be ensured not lower than +18 °C and not higher than +28 °C.

In the repair area of ​​the closed switchgear, a temperature of at least +5 °C must be ensured during repair work.

When heating rooms that contain SF6 equipment, heating devices with a heating surface temperature exceeding 250 °C (for example, heaters such as heating elements) should not be used.

4.2.108. Holes in the enclosing structures of buildings and premises after laying current conductors and other communications should be sealed with a material that provides fire resistance not lower than the fire resistance of the enclosing structure itself, but not less than 45 minutes.

4.2.109. To prevent the entry of animals and birds, other openings in external walls must be protected with nets or gratings with cells measuring 10 x 10 mm.

4.2.110. Overlapping cable ducts and double floors must be made of removable slabs made of fireproof materials flush with the clean floor of the room. The weight of an individual 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, their installation in pipes is allowed.

Electrical wiring of lighting and control and measurement circuits located inside chambers or located near non-insulated live parts can be allowed only to the extent necessary for connections (for example, to instrument transformers).

4.2.112. Laying related (non-transit) heating pipelines into the switchgear premises is permitted provided that solid welded pipes are used without valves, etc., and welded ventilation ducts are used without valves and other similar devices. Transit laying of heating pipelines is also permitted, provided that each pipeline is enclosed in a continuous waterproof shell.

4.2.113. When choosing a switchgear circuit containing SF6 devices, simpler circuits should be used than in air-insulated switchgear.

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 the adopted electrical circuit of the substation, i.e. arrangement of electrical devices indoors or outdoors with connections between them with 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 incoming 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 with minimal construction costs, fire safety and cost-effectiveness of operation, possibility of expansion, maximum use of large-block prefabricated units.

Reliability of switchgear operation is ensured by the correct selection and correct installation of 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 above.

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 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 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 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 (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 chambers is a 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.

premises. 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 a circuit breaker in a cabinet or a roll-out trolley with a circuit breaker, similar to an indoor switchgear installation.

Cabinets KRZ-10 (Fig. 2.3) for outdoor installation 6 - 10 kV are intended for networks in 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 in 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 of a relatively small height; prefabricated busbars are mounted on supports that are also of relatively low height.