Chapter 4.1. SWITCHING DEVICES WITH VOLTAGE up to 1 kV AC and up to 1.5 kV DC Application area Question. Which RUs are covered by this chapter of the Rules? Answer. Applies to switchgear and low-voltage switchgear with voltage up to 1 kV AC and up to 1.5 kV

Chapter 4.2. SWITCHING DEVICES AND SUBSTATIONS WITH VOLTAGE ABOVE 1 kV Scope, definitions Question. Which switchgear and transformer substations (SS) are covered by this chapter of the Rules? Applies to stationary switchgears and substations of alternating current

Open switchgears Question. How should flexible wire connections be made in spans, in loops at supports, in spans and to hardware terminals? Should be carried out by crimping using connecting clamps, and the connections in the hinges at

In-shop switchgears and transformer substations Question. Where can the in-house switchgears and substations be located? RU and substation with oil-filled equipment can be located on the first and second floors in the main and auxiliary rooms

Input devices, switchboards, distribution points, panel boards Question. What should be installed at the entrance to the building? Answer. VU or ASU must be installed. One or more VU or ASU can be installed in the building (7.1.22). What

Switchgears, transformer and converter substations Question. Is it allowed to build switchgears with voltage up to 1 kV and above, transformer substations and converting substations with electrical equipment directly in explosive zones general purpose(without funds

Switchgears, transformer and distribution substations Question. Is it allowed to install switchgear with voltage up to 1 kV and higher in fire hazardous areas? Their installation in fire hazardous areas of any class is not recommended. If it is necessary to install the switchgear

1.8.25. Complete switchgears for indoor and outdoor installation (KRU and KRUN) Question 113. What is the volume and standards for measuring the insulation resistance of KRU and KRUN? Insulation resistance measurements are subject to: primary circuits. The measurement is carried out with a megohmmeter at

Chapter 4.1. SWITCHING DEVICES WITH VOLTAGE UP TO 1 KV AC AND UP TO 1.5 KV DC Scope Question 1. Which switchgears are covered by this chapter of the Rules? Applies to switchgear

Chapter 4.2. SWITCHING DEVICES AND SUBSTATIONS WITH VOLTAGE ABOVE 1 KV Scope, definitions Question 20. Which switchgears and transformer substations (SS) are covered by this chapter of the Rules? Spreads on

Open switchgears Question 53. How should flexible wire connections be made in spans, in hinges at supports, in spans and to hardware terminals? Should be carried out by crimping using connecting clamps, and the connections in the hinges at

In-shop switchgears and transformer substations Question 98. Where can in-shop switchgears and substations with oil-filled equipment be located? They can be located on the first and second floors in the main and auxiliary premises of production facilities,

Section 2 Complete transformer substations and switchgears 2.1. COMPLETE TRANSFORMER SUBSTATIONS Complete block transformer substations (KTPB) (Fig.2.1) are intended for receiving, converting and distributing electrical

2.2. COMPLETE DISTRIBUTION DEVICES A complete distribution device (KRU), consisting of prefabricated one-way service chambers "SamaraElectron-Shield" series KSO-SESCH (hereinafter KSO), is designed to receive and distribute electrical energy

Lecture No. 6 "Switchgears and substations"

Requirements for buildings and structures of switchgears.

In the rooms of the switchgear, the doors and windows must always be closed, and the openings in the partitions between the devices containing oil must be sealed. All openings in the cable passages are sealed. To prevent the entry of animals and birds, all openings and openings in the outer walls of the premises are sealed or closed with nets with a mesh size (1 × 1) cm. The live parts of ballasts and protection devices must be protected from accidental touches. In special rooms (electrical machines, switchboards, control stations, etc.), open installation of devices without protective covers is allowed. All switchgears (shields, assemblies, etc.) installed outside the switchgear enclosures and closed rooms must have locking devices that prevent non-electrical personnel from accessing them. Electrical equipment of switchgears of all types and voltages must satisfy the operating conditions, both under normal modes and with short circuits, overvoltages and overloads. The insulation class of electrical equipment must correspond to the rated voltage of the network, and the overvoltage protection devices must correspond to the insulation level of the electrical equipment. When electrical equipment is located in an area with a polluted atmosphere, measures must be taken to ensure the reliability of the insulation:

Heating by the induced current of structures located near live parts through which the current flows, and accessible to the touch of personnel, should not exceed 50 ° C. The air temperature inside the indoor switchgear in the summer should be no more than 40 ° C. If it rises, measures must be taken to reduce the temperature of the equipment or to cool the air. The air temperature in the compressor station room must be maintained within (10 ¸ 35) ° С; in the room of gas-insulated complete switchgears (hereinafter - GIS) - within (1 ¸ 40) ° С. The temperature of the plug-in busbar connections in the switchgear must be monitored according to the approved schedule. The distances from the live parts of the outdoor switchgear to trees, tall bushes must be such that the possibility of overlap is excluded. The floor covering in indoor switchgear, switchgear and switchgear must be such that cement dust does not form. Premises intended for the installation of cells of a complete switchgear with gas-insulated insulation (hereinafter - GIS), as well as for their revision before installation and repair, must be isolated from the street and other premises. Walls, floors and ceilings should be painted with dustproof paint and should be cleaned wet or vacuum method... The premises should be equipped with supply and exhaust ventilation with air suction from below. The supply ventilation air must pass through filters that prevent dust from entering the room.

In this lecture, we will consider the substations of Consumers with voltage from 0.4 to 220 kV. The room of the consumer's switchgear, adjacent to the premises belonging to third-party organizations, and having live equipment, must be isolated from them. It must have a separate lockable exit. The RU equipment serviced by the Consumers and used by the energy supplying organization must be controlled on the basis of the instructions agreed upon by the Consumer and the energy supplying organization. In the rooms of the switchgear, the doors and windows must always be closed, and the openings in the partitions between the devices containing oil must be sealed. All openings in the cable passages are sealed. To prevent the entry of animals and birds, all openings and openings in the outer walls of the premises are sealed or closed with nets with a mesh size (1 × 1) cm. The live parts of ballasts and protection devices must be protected from accidental touches. In special rooms (electrical machines, switchboards, control stations, etc.), open installation of devices without protective covers is allowed. All switchgears (shields, assemblies, etc.) installed outside the switchgear enclosures and closed rooms must have locking devices that prevent non-electrical personnel from accessing them. Electrical equipment of switchgears of all types and voltages must satisfy the operating conditions, both under normal modes and with short circuits, overvoltages and overloads. The insulation class of electrical equipment must correspond to the rated voltage of the network, and the overvoltage protection devices must correspond to the insulation level of the electrical equipment. When electrical equipment is located in an area with a polluted atmosphere, measures must be taken to ensure the reliability of the insulation:

In open switchgears (hereinafter - OSU) - strengthening, washing, cleaning, coating with hydrophobic pastes;

In closed switchgears (hereinafter - ZRU) - protection against the ingress of dust and harmful gases;

In outdoor switchgears - sealing of cabinets and treatment of insulation with hydrophobic pastes.

Heating by the induced current of structures located near live parts through which the current flows, and accessible to the touch of personnel, should not exceed 50 ° C. The air temperature inside the indoor switchgear in the summer should be no more than 40 ° C. If it rises, measures must be taken to reduce the temperature of the equipment or to cool the air. The air temperature in the compressor station room must be maintained within (10 ¸ 35) ° С; in the room of gas-insulated complete switchgears (hereinafter - GIS) - within (1 ¸ 40) ° С. The temperature of the plug-in busbar connections in the switchgear must be monitored according to the approved schedule. The distances from the live parts of the outdoor switchgear to trees, tall bushes must be such that the possibility of overlap is excluded. The floor covering in indoor switchgear, switchgear and switchgear must be such that cement dust does not form. Premises intended for the installation of cells of a complete switchgear with gas-insulated insulation (hereinafter - GIS), as well as for their revision before installation and repair, must be isolated from the street and other premises. Walls, floors and ceilings should be painted with dustproof paint.

Premises should be cleaned using a wet or vacuum method. The premises should be equipped with supply and exhaust ventilation with air suction from below. The supply ventilation air must pass through filters that prevent dust from entering the room.

Chapter 4.2. Switchgears and substations with voltage above 1 kV

4.2.1. This chapter of the Rules applies to stationary switchgear and alternating current substations with voltage above 1 kV. The rules do not apply to special switchgear and substations regulated by special technical conditions, and to mobile electrical installations.

4.2.2. A switchgear is an electrical installation that serves to receive and distribute electricity and contains switching devices, busbars and connecting buses, auxiliary devices (compressor, battery, etc.), as well as protection, automation and measuring instruments.

An open switchgear (OSG) is called a switchgear, all or the main equipment of which is located in the open air.

A closed switchgear (ZRU) is called a switchgear, the equipment of which is located in the building.

4.2.3. A complete switchgear is called 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 designed for indoor installation is abbreviated as KRU. Complete switchgear designed for outdoor installation is abbreviated as KRUN.

4.2.4. A substation is an electrical installation used to transform and distribute electricity and consists 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 switchgear) is a substation (switchgear) that is directly adjacent (adjacent) to the main building.

4.2.6. A built-in substation (built-in switchgear) is a closed substation (closed switchgear), inscribed (inscribed) into the circuit of the main building.

4.2.7. An in-shop substation is a substation located inside an industrial building (open or in a separate closed room).

4.2.8. A complete transformer (converter) substation is a substation consisting of transformers (converters) and blocks (switchgear or switchgear and other elements) supplied assembled or fully prepared for assembly. Complete transformer (converter) substations (KTP, KPP) or their parts installed in an enclosed space refer to indoor installations, installed in the open air - to outdoor installations.

4.2.9. A pole (mast) transformer substation is an open transformer substation, all equipment of which is installed on structures or on overhead line supports at a height that does not require a substation fence.

4.2.10. Distribution point (RP) is called a switchgear designed to receive and distribute electricity at one voltage without conversion and transformation, which is not part of the substation.

4.2.11. A chamber is a room for installing devices and tires.

A closed chamber is a chamber that is closed on all sides and has solid (not mesh) doors.

A fenced chamber is a chamber that has openings protected in whole or in part by non-continuous (mesh or mixed) fences.

Mixed fences are mesh and solid sheet fences.

The explosion chamber is called closed chamber, designed to localize possible emergency consequences in case of damage to the devices installed in it and having an exit to the outside or to the explosive corridor.

4.2.12. A service corridor is a corridor along the cameras or switchgear cabinets, designed to service devices and buses.

The blast corridor is the corridor into which the blast chamber doors open.

General requirements

4.2.13. Electrical equipment, live parts, insulators, fasteners, fences, supporting structures, insulating and other distances should be selected and installed in such a way that:

1) forces caused by normal operating conditions of the electrical installation, heating, electric arc or other phenomena accompanying its operation (sparking, gas emission, etc.) could not lead to damage to the equipment and the occurrence of a short circuit or ground fault, as well as harm the maintenance personnel ;

2) in case of violation of the normal operating conditions of the electrical installation, the necessary localization of damage caused by the action of the short circuit was ensured;

3) when the voltage is removed from any circuit, the devices, live parts and structures related to it could undergo safe inspection, replacement and repairs without disrupting the normal operation of adjacent circuits;

4) the possibility of convenient transportation of equipment was provided.

The requirements of clause 3 do not apply to switchgear of the type of assemblies above 1 kV in substations, which are repaired when the entire switchgear is turned off.

4.2.14. When using open knife disconnectors or open knife separators to turn off and turn on the current of unloaded transformers, charging or equalizing current of power lines, earth fault current, the distances between live parts and from live parts to the ground must comply with the requirements of this chapter and special directive documents approved in established order.

4.2.15. The selection of devices, conductors and insulators for short circuit conditions should be made in accordance with Ch. 1.4.

4.2.16. The structures on which the electrical equipment specified in 4.2.15 is installed and fixed must withstand the loads and effects from the weight of the equipment, wind, ice, as well as those arising from short circuits.

Building construction located near live parts and accessible to the touch of personnel should not heat up from exposure electric current up to a temperature of 50 ° C and above; inaccessible to touch - up to 70 ° C and above.

Structures may not be checked for heating if an alternating current of 1000A or less passes through the current-carrying parts located near them.

4.2.17. All circuits of the switchgear must provide for the installation of disconnecting devices with a visible gap, providing the ability to disconnect all devices (switches, separators, fuses, current transformers, voltage transformers, etc.) of each circuit from the busbars, as well as from other voltage sources.

This requirement does not apply to switchgear and switchgear cabinets with withdrawable trolleys, high-frequency interrupters and coupling capacitors, voltage transformers installed on outgoing lines, arresters installed on the terminals of transformers and on outgoing lines, as well as on power transformers with cable entries.

In some cases, due to design or circuit considerations, it is allowed to install current transformers up to the disconnector that disconnects the rest of the circuit devices from voltage sources.

4.2.18. The switch or its actuator must have a clearly visible and reliably working position indicator ("on", "off"). The use of signal lamps as the only indicators of the position of the switch is not allowed. If the switch has no open contacts and its drive is separated by a wall from the switch, then the indicator should be both on the switch and on the drive.

4.2.19. When the switchgear and substations are located in places where the air can contain substances that impair the performance of insulation or have a destructive effect on equipment and buses, measures must be taken to ensure reliable operation of the installation: reinforced insulation is used; tires made of material resistant to environmental influences are used, or they are painted with a protective coating; RU and substations are located on the side of the prevailing wind direction; Switchgear and substations are made according to the simplest schemes; closed version of switchgear and substations, protected from the penetration of dust, harmful gases or vapors into the room.

When constructing outdoor switchgear near sea coasts, salt lakes, chemical plants, as well as in places where long-term operating experience has established the destruction of aluminum from corrosion, special aluminum and steel-aluminum wires protected from corrosion should be used.

4.2.20. When switchgear and substations are located at an altitude of more than 1000 m above sea level, air insulation gaps, suspension insulation and external insulation of electrical equipment should be selected in accordance with the requirements given in 4.2.53, 4.2.54, 4.2.82, 4.2.83, taking into account corrections to compensate for the decrease in the dielectric strength of the insulation at a reduced atmospheric pressure.

4.2.21. In outdoor switchgear, KRUN and in unheated indoor switchgear, where the ambient temperature can be below minus 25 ° C, oil heating of oil switches should be provided.

In addition, regardless of the minimum temperature, heating of the mechanisms of drives of oil and air switches, valve blocks of air switches, their unit cabinets, as well as other cabinets in which equipment or clamps of indoor installation are used, should be provided.

Heating of relays and measuring instruments should be carried out in accordance with the requirements given in GOST, heating of meters - in accordance with 1.5.27 and 1.5.28.

4.2.22. Busbars of switchgear and substations should be performed, as a rule, from aluminum, steel-aluminum and steel wires, strips, pipes and tires made of aluminum profiles and aluminum alloys for electrical purposes.

The conductors should be made in accordance with the requirements of Ch. 2.2.

4.2.23. The designation of the phases of electrical equipment and busbars of switchgear and substations must be carried out in accordance with the requirements of Ch. 1.1.

4.2.24. Switchgears 3 kV and above must be equipped with an operational interlock, which excludes the possibility of:

switching on switches, separators and disconnectors for earthing knives and short-circuits;

switching on grounding knives on the busbar, not separated by disconnectors from the busbar, which is energized;

disconnection and switching on by separators and disconnectors of the load current, if this is not provided for by the design of the device.

It is allowed to install only a mechanical interlock with a disconnector drive and a device for locking the grounding knives with locks in the off position on the earthing knives of the line disconnectors on the line side.

For RU with simple schemes electrical connections it is recommended to use a mechanical (key) operational blocking, and in all other cases - electromagnetic. The disconnector drives, accessible to unauthorized persons, must have devices for locking them with locks in the open and closed positions.

4.2.25. Switchgears and substations above 1 kV must be equipped with stationary grounding blades, providing, in accordance with safety requirements, grounding of devices and busbars, as a rule, without the use of portable grounding.

Grounding blades should be painted black. The handles of the earthing knife drives should be painted red, and the handles of the other drives in the equipment colors.

In places where stationary grounding knives cannot be used, contact surfaces must be prepared on current-carrying and grounding buses for connecting portable grounding conductors.

In the presence of voltage transformers, the busbars should be earthed, as a rule, by the earthing knives of the voltage transformer disconnectors.

4.2.26. Mesh and mixed fences of live parts and electrical equipment must have a height above the level of the layout for outdoor switchgear and openly installed transformers of 2 or 1.6 m (taking into account the requirements of 4.2.57 and 4.2.58), and above the floor level for indoor switchgear and transformers installed inside buildings, 1.9 m; nets must have holes of at least 10x10 mm and no more than 25x25 mm, as well as devices for locking them with a lock. The lower edge of these fences in the outdoor switchgear should be located at a height of 0.1-0.2 m, and in the indoor switchgear - at the floor level.

External barriers should be made in accordance with the requirements given in 4.2.39.

The use of barriers is allowed when entering the chambers of switches, transformers and other devices for examining chambers in the presence of voltage on live parts. Barriers should be installed at a height of 1.2 m and be removable. If the floor of the cells is more than 0.3 m above the ground level, it is necessary to leave a distance of at least 0.5 m between the door and the barrier, or provide a platform in front of the door for inspection.

4.2.27. In the case when deformations of wires (tires) caused by changes in temperature, vibration, etc., can cause dangerous mechanical stresses in wires or insulators, measures should be taken to prevent the occurrence of such stresses (compensators, weakened tension, etc.) ...

4.2.28. Indicators of the level and temperature of oil of oil-filled transformers and apparatus and other indicators characterizing the condition of the equipment should be located in such a way as to provide convenient and safe conditions for access to them and monitoring them without removing the voltage (for example, from the side of the passage to the chamber) ...

For oil sampling, the distance from the floor or surface of the earth to the crane of the transformer or apparatus must be at least 0.2 m or an appropriate pit must be provided.

4.2.29. The wiring of the protection, measurement, signaling and lighting circuits laid through oil-filled electrical devices must be made with oil-resistant wires.

4.2.30. Outdoor transformers, reactors and condensers should be painted in light colors with weather and oil resistant paints to reduce heat from direct sunlight.

4.2.31. Switchgears and substations must be equipped with electric lighting. Lighting fixtures must be installed in such a way that they can be safely serviced.

4.2.32. Switchgear and substations must be provided with telephone communications in accordance with the adopted service system.

4.2.33. The placement of switchgear and substations, the general plan and engineering preparation of the territory and their protection from flooding, landslides, avalanches, etc. must be performed in accordance with the requirements of the SNiP of the Gosstroy of Russia.

4.2.34. The layout and design of outdoor switchgear and indoor switchgear should provide for the possibility of using mechanisms, including special ones, for the production of installation and repair work.

4.2.35. The distances between switchgear (substations) and trees with a height of more than 4 m should be such that damage to equipment and busbars is excluded when a tree falls.

4.2.36. For switchgears and substations located in the area of ​​residential and industrial buildings, measures should be taken to reduce noise generated by operating electrical equipment (transformers, synchronous compensators etc.), to the values ​​specified in SNiP II-12-77 of the Gosstroy of Russia.

4.2.37. Switchgears and substations with permanent personnel on duty, with operational and repair personnel permanently located at them, as well as in the presence of residential buildings nearby, must be provided with drinking water by arranging a drinking water supply system, constructing artesian wells or wells.

4.2.38. For switchgears and substations with constant duty of personnel with a water supply, insulated latrines with sewerage should be arranged. In the absence of sewer mains near substations, it is allowed to perform local sewer devices (sedimentation tanks, filters). For substations without constant personnel on duty, it is allowed to install non-insulated latrines with watertight cesspools.

When substations of 110 kV and higher are located without constant personnel on duty near the existing water supply and sewerage systems (at a distance of up to 0.5 km), sanitary sewerage units should be provided in the building of the general substation control center (OCP).

4.2.39. The territory of the outdoor switchgear and the substation must be fenced with an external fence 1.8-2.0 m high. External fences with a height of more than 2.0 m can be used in places with high snow drifts, as well as for substations with a special regime of admission to their territory.

Auxiliary facilities (workshops, warehouses, control rooms, etc.) located on the territory of the outdoor switchgear should be fenced off with an internal fence with a height of 1.6 m.

When an outdoor switchgear (substation) is located on the territory of power plants, these outdoor switchgear (substations) must be fenced with an internal fence with a height of 1.6 m.

Fences can be solid, mesh or lattice.

Fences may not be provided:

for closed substations located in the protected area of ​​an industrial enterprise;

for closed substations located on the territory of cities and towns;

for pole substations (see also 4.2.134).

4.2.40. Metal constructions Indoor switchgear, outdoor switchgear and substations, as well as underground parts of metal and reinforced concrete structures must be protected from corrosion.

4.2.41. For the territory of outdoor switchgear and substations, in which, under normal operating conditions, oil leaks from the oil control room, from oil depots, from machine rooms, as well as from transformers and switches during repair and other work, oil leaks should be provided for its collection and removal from in order to exclude the possibility of oil getting into water bodies.

4.2.42. As an operating current at substations, alternating current should be used in all cases when possible and leads to a simplification and reduction in the cost of electrical installations while ensuring the necessary reliability of their operation.

In the outdoor switchgear (TP), they provide passage along the switches for mobile installation and repair mechanisms and devices, as well as mobile laboratories; the passage gauge must be at least 4 m in width and height (Fig. 1).
Flexible busbars are mounted from stranded wires. Connections of flexible tires are made in loops at the supports by welding, and branches in the span - in a way that does not require cutting the tires.
The busbars of the outdoor switchgear are suspended on single strings of insulators. Double strings are used only in cases where a single string does not satisfy the conditions for mechanical strength. The use of dividing (cut-in) garlands is not allowed. Fastening flexible tires and cables in tension and suspension clamps with respect to strength must comply with the requirements given in the PUE. When determining the loads on flexible tires, the weight of the strings of insulators and descents to devices and transformers is taken into account, and when calculating the loads on structures, the weight of a person with a tool and mounting devices is additionally taken into account.
The safety factor of mechanical strength for suspension insulators under loads must be at least 3 in relation to the test load. The design mechanical forces transmitted during a short circuit by rigid tires to the support insulators are taken in accordance with the requirements of the PUE.
The safety factor of mechanical strength in coupling fittings for flexible tires under loads must be at least 3 in relation to the breaking load.
For fastening and insulating wires and lightning protection cables in open switchgears (OSG), suspension insulators are used, which consist of an insulating body (glass PS or porcelain PF), a cap made of ductile iron, and a steel rod. With a cement bond, the cap and rod are reinforced in the insulating body. Insulators PS and PF are designed to work in areas with an unpolluted atmosphere, and PSG and PFG - in areas with a polluted atmosphere.

Rice. 1. Plan and sections of a typical 110 / 6-10 kV GPP with two 40 MB A transformers:
a - plan; b - section; 7 - 110 kV outdoor switchgear; 2 - 6-10 kV indoor switchgear; 3 - transformer; 4- VL 110 kV; 5 - repair site; 6 - lightning rod; 7- protective cable; 8- disconnector; 9- separator; 10- short-circuiter; 11 - spark gap; 12 - railway track; 13 - conclusions from the split windings of the transformer

Rice. 2. MKP-35 circuit breaker in section along the pole:

1- drive mechanism; 2, 5 - inputs; 3 - cover; 4 - current transformer; 6 - pipe; 7- barbell; 8 - arc extinguishing device; 9- movable contacts

Power oil switches are designed to turn on, turn off and switch operating currents during normal and short-circuit currents in emergency modes that may occur in the lines of the switchgear. Depending on the arc-extinguishing medium, the switches are divided into liquid and gas. The most common liquid switches are oil switches, which, depending on the volume, are classified into multi- and low-volume. For outdoor switchgear substations with a voltage of 35 kV, multi-volume oil switches of the C, MKP, U, etc. series are widely used.
MCP switches are classified as high-speed oil three-phase devices with a separate tank for each phase. All the poles of the switches are connected to each other and controlled by the drive. The switches have two breaks per pole and are used for currents of 0.63 and 1 kA for voltages of 35-110 kV and outdoor installation. In 35 kV circuit breakers, three tanks (phases) are mounted on a common frame, and in 110 kV circuit breakers, each tank is installed separately on the foundation. All circuit breakers have built-in current transformers.
The design of the MKP-35 circuit breaker for a voltage of 35 kV is shown in Fig. 2. On the cover 3 there are two bushings 5, the outer part of which is protected by porcelain insulators 2 Under the cover
installed current transformers 4 and a drive mechanism /, assembled in a welded case. A bakelite guide tube 6 with an internal oil buffer is fixed in the lower part of the body. An insulating rod 7 passes through the buffer and the guide pipe, at the bottom of which movable contacts 9 are fixed. At the lower end of the current-conducting rod, a fixed contact and an arc-extinguishing device 8, made according to the principle of a cross-slotted oil blast chamber, are fixed.
Air circuit breakers VVU-35A are also switching devices installed on outdoor switchgear high voltage for breaking electrical circuits under load and disconnecting short-circuit currents.
The arc chute of such a circuit breaker has two main breaks. Each break is bridged by its own active resistance with auxiliary contacts. An even distribution of voltage between two discontinuities is ensured by shunt capacitors placed in a porcelain cover. The bushings to the arc chute are made of epoxy compound and protected from moisture by porcelain covers. Interrupter chambers for 35 kV circuit breakers are installed on a support column made of hollow porcelain insulators.
Inside the support insulation of the chamber, there are two fiberglass air ducts: one for supplying compressed air to the arc-extinguishing chambers, the other for impulse air supply when turned off and dumped when turned on.
The base of the pole or its element is a frame with a plinth, which is connected with copper pipes to the switch cabinet of the circuit breaker. The cabinet is connected to the air duct of the substation compressor unit.
Disconnectors are used to manually turn on and off de-energized sections of live electrical circuits, as well as grounding disconnected sections, if they are equipped with stationary grounding devices.
Disconnectors of the RND (3) series of the horizontal-rotary type are manufactured in the form of separate poles. A steel frame, at the ends of which two bearing assemblies are fixed, serves as the base of each pole.
Shafts with supporting insulating columns rotate in bearings, on the upper flanges of which the knives of the contact system and contact leads are fixed. The latter are connected to the main knives by flexible conductors of strip copper. The detachable contact of the main knives of the contact system consists of lamellas connected in pairs by a tie rod or a bolt with a spring that provides the required contact pressure.
The pole of the disconnector to which the drive is connected is called the master, the rest of the poles connected by the rods to the master are driven. When operating the disconnector, the contact blades rotate through an angle of 90 °.
The grounding knife is a steel tube, one end of which is provided with a lamellar contact, the other is welded to its shaft. The fixed contact of the earthing blade is attached to the contact blade of the disconnector. The grounding blades are manually activated and deactivated, and the main contact blades are manually, electrically or pneumatically operated.
Separators are used to automatically disconnect a de-energized damaged section of a line or transformer. Single-pole separators for a voltage of 35 kV are connected into one three-pole apparatus. The separator drive provides automatic shutdown and manual activation of the device.
KRN-35 short-circuits are designed to create an artificial short circuit, causing the circuit breaker to disconnect the protective power line.
The short-circuiter consists of a base, an insulating column, on which a fixed contact is fixed, and a grounding knife, connected to the drive by a rod. The base of the short-circuiter is a welded structure designed for the installation of an insulating column with a fixed contact. For the joint operation of the short-circuiter with the separator, a TShL-0.5 current transformer is built into the grounding circuit, the secondary windings of which are connected to the separator drive relay. The base of the short-circuiter is isolated from the ground with insulators. The drive rod has an insulating insert. After the short-circuit is turned on, the current flows through the circuit: supply bus - fixed contact - grounding knife - flexible connection - bus located on the insulating strip of the base, - grounding bus, passed through the current transformer window, - ground.
Current transformers TFEM-35 are manufactured as single-stage ones. They consist of a primary and secondary winding placed in a porcelain cover filled with transformer oil. The windings are made in the form of two links inserted into one another. The primary winding is made of two or four sections, which are connected in series, parallel and mixed, depending on the transformation ratio. Switching of sections is carried out by jumpers at the terminals of the primary winding.
Voltage transformers are conventional low power step-down transformers. They are made in one and three phase. The secondary (lowest) voltage, to which the measuring devices and protection devices are turned on, of all voltage transformers is 100 V. Such transformers are used to power the voltage coils of the measuring devices.
Power transformers are designed to increase or decrease the AC voltage (Fig. 3).
Currently, various power transformers are used, which are characterized by rated power, voltage class, conditions and operating modes, and design. Depending on the rated power and voltage class, they are divided into several groups (dimensions).
According to the operating conditions, the nature of the load or the operating mode, power transformers are distinguished for general purpose, regulation and special (mine, traction, converter, starting, electric furnaces).


Rice. 3. Three-phase three-winding transformer with a capacity of 16 MB * A 110/38, 5/11 kV:
1 - high voltage inputs (HV); 2 - medium voltage inputs (s.n.); 3- insulating cylinder; 4 - low voltage inputs (n.n.); 5 - switch drive; 6- exhaust pipe; 7- expander; 8- magnetic circuit; 9 - switch of winding branches (v.n.); 10- winding (h.n.); 11 - shielding turns of the winding (h.n.); 12 - thermosiphon filter; 13 - cart; 14 - transformer tank; 15- tubular radiator; 16 - electric fans

The conventional designation of various transformers consists of letters characterizing the number of phases and windings, the type of cooling and switching of taps, and numbers characterizing the rated power and voltage class, the year of manufacture of the transformer of this design (the last two digits), climatic version and category of placement.
The letter T denotes three-winding transformers (they do not have two-winding designations), the letter N stands for transformers with an on-load tap-changer. Other letters are also used: A (for autotransformers before the designation of the number of phases), P (for transformers with split winding LV after designation of the number of phases), 3 (for sealed oil transformers or with a non-combustible liquid dielectric with a protective nitrogen cushion after designation of the type of cooling), C (for auxiliary transformers at the end of the letter designation).
The rated power and voltage class are indicated through a dash after the letter designation in the form of a fraction (the numerator is the rated power in kilovolt-amperes, the denominator is the voltage class of the transformer in kilovolts).
The versions of transformers intended for operation in certain climatic regions are designated by the letters U, XL, T (with a temperate, cold, tropical climate).
Currently, the electrical industry manufactures oil-immersed transformers of I and II dimensions (power up to 630 kV * A, voltage class up to 35 kV) types TMG and TMVG new series. Distinctive feature of these transformers is a split sealed tank design, which makes it possible to exclude contact of the inner volume of the transformer with environment.
These transformers are completely filled, up to the cover, with transformer oil, and temperature fluctuations in its volume are compensated for by changing the volume of the tank with corrugated walls. The transformers are filled with degassed oil under high vacuum.
Depending on the type of transformer, the tank is made oval or rectangular. It consists of an upper corner frame, a corrugated wall made of thin sheet steel, a lower shell with a welded bottom. Oil conservator, thermosiphon and air filters and cooling radiators. The sealed design and the use of corrugated tank walls can significantly reduce weight and dimensions. The service life of the transformers is 25 years with a reduced amount of maintenance and without major overhauls... However, transformers of the TMG and TMVG types require more high level installation and operation. The corrugated walls of the tank are made of sheet steel and are sensitive to mechanical stress. Therefore, the installation and operating personnel must be extremely careful when transporting, installing and maintaining sealed transformers. When transporting transformers, it is not allowed to unfasten them using plates.
At present, a new series of 35 kV transformers with a capacity of 1000-6300 kV * A is being introduced. The weight of the new series of transformers and no-load losses have been reduced by an average of 20%.

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REQUIREMENTS FOR DISTRIBUTION DEVICES AND THEIR SERVICE TASKS

Switchgears (RU) of substations are complexes of structures and equipment designed to receive and distribute electrical energy.
Switchgears are open (switchgear) and closed (switchgear). Complete switchgears (KRU) for indoor and outdoor installation (KRUN) are widely used. They are made in stationary and withdrawable versions, delivered assembled or fully prepared for assembly. Sealed switchgears in which SF6 is used as an insulating and arcing medium are called GIS.

TO switchgear equipment has the following requirements:

1. According to its nominal data, the equipment of the switchgear must satisfy the operating conditions both in normal mode and during short circuit. Under normal conditions, the 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 the short circuit mode, the switchgear equipment must have the required thermal and electrodynamic resistance.
2. The insulation of the equipment must correspond to the rated voltage of the network and withstand potential increases in operation during switching and atmospheric overvoltages. One of the main conditions for reliable operation insulating structures keeping the insulation clean - systematic cleaning, washing, coatings with hydrophobic pastes; for indoor switchgear - protection against the penetration of dust and harmful gases into the premises; in KRUN - sealing of cabinets, coating of insulation with hydrophobic pastes.
3. The equipment must operate reliably under permissible overloads, which must not cause damage and reduce its service life.
4. Industrial premises of the switchgear must be comfortable and safe when servicing equipment by personnel. Switchgears with a voltage of 400 kV and above must be equipped with biological protection means in the form of stationary, portable or inventory screens, personal protective equipment - shielding suits. The heating of structures located near live parts, accessible to the touch of personnel, should not exceed 50 ° C.
5. Temperature regime and the air humidity in the indoor switchgear must be maintained in such a way 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. The windows in the indoor switchgear must be locked or protected with nets, and the openings and openings in the walls or chambers must be sealed to exclude the possibility of animals entering, etc. birds. The roof must be in good condition. Floor coverings must be free from the formation of cement dust.
6. The switchgear must be equipped with working and emergency electric lighting. Lighting equipment should be installed in such a way as to ensure safe maintenance.
7. For the orientation of personnel, all equipment and especially the drives of switching devices must be provided with clear, conspicuous inscriptions indicating the name of the equipment and the dispatching name of the electrical circuit to which the inscription refers. In RU, the atypical arrangement of the handles of busbar disconnector drives is unacceptable, when, for example, some disconnectors are turned off by moving the drive handle down, others up. Switches and their drives, disconnectors, isolators, short-circuits and stationary earthing switches must have position indicators "On" and "Off". The switchgear must be equipped with an interlock preventing the possibility of erroneous operations with disconnectors, grounding knives, short-circuits. Locking devices, except for mechanical ones, must be permanently sealed.
8. In the premises of the switchgear there must be safety equipment and fire extinguishing equipment.

The tasks of RU maintenance are:

1. ensuring compliance of the reactor plant operating modes and individual electrical circuits technical specifications installed equipment;
2. maintaining in each period of time such a scheme of switchgear and substations so that they meet the requirements of reliable operation of the power system and trouble-free selective operation of relay protection and automation devices to the greatest extent;
3. systematic supervision and maintenance of equipment and facilities of the reactor plant, elimination of identified faults and defects in the shortest possible time, since their development may lead to failures in work and accidents;
4. control over the timely implementation of preventive tests and equipment repair;
5. observance of the established order and sequence of switching operations in the switchgear.

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

1. at facilities with constant personnel on 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 objects without constant 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, wet snow, ice) or increased pollution, the outdoor switchgear is subjected to additional inspections. During the inspection, it is strictly forbidden to carry out any work on the equipment.
During inspections of the reactor plant, all comments are recorded in the log of defects and malfunctions, brought to the attention of the managers of the power company, who take appropriate measures to eliminate the identified violations as soon as possible.
Switchgears with voltage above 1000 V are operated in accordance with the "Rules for the technical operation of power plants and networks".
Tests of the switchgear electrical equipment should usually be carried out during the periods of its repair.
Maintenance repairs RP electrical equipment, as well as checking its operation (testing) must be carried out in accordance with the schedule approved by the chief engineer of the power company, with the exception of unforeseen emergency and other urgent works that are carried out outside the schedule with their own procedure for registering these works.