Acceptance of the cable line into operation. Handover and acceptance of cable lines into operation The procedure for acceptance of an overhead cable line into operation

Lines with voltages below 1000 V are checked for continuity (no breakage), and for compliance with the insulation resistance standard of 0.5 MΩ (PUE). If the measured insulation resistance is less than 0.5 MΩ, then an additional insulation test is performed with an increased voltage of 1000 V for 1 minute. If the result is positive, the line is put into operation.

Lines with voltages above 1000 V.

Continuity check.

Checking the phasing of the cable cores: core L1 (A) must be connected to the yellow bus, core L2(B) to the green bus, core L3(C) to the red bus.

Testing cable lines with increased voltage.

Newly laid cable lines are tested with rectified voltage for 10 minutes.

Single-core cables with cross-linked polyethylene insulation are tested with an alternating voltage with a frequency of 0.1 Hz or a direct voltage applied between the conductor and the metal screen for 15 minutes.

After testing with constant voltage, it is necessary to ground the current-carrying core or connect it to the screen for at least 1 hour.

Test voltage value (kV) at Unom

The test voltage is applied to one cable core. The rest are connected to the shell (screen) and grounded. When testing, the voltage rise should be done smoothly, no faster than 1 kV per second. The leakage current of a serviceable cable (except for cables with XLPE insulation) must be stable and should not exceed 300 - 500 µA for cables up to 10 kV and 1.5 - 1.8 mA for cables 20 - 35 kV.. Permissible value of the asymmetry coefficient (Imax/Imin) is in the range of 2 - 3.

3.10. Maintenance of cable lines.

Supervision of cable routes, cable structures and cable lines is carried out in order to check their condition by periodic walk-through and inspection within the time limits prescribed by the PTE and local instructions. Extraordinary rounds and inspections are carried out during floods and after rainstorms, as well as when lines are disconnected by relay protection.

When making rounds to inspect cable routes, you must:

Check that no work is being carried out on the route that is not approved by the energy company, and also that there are no blockages of the route with garbage, slag, waste, and that there are no failures or landslides;

Inspect the intersections of cable routes with railways;

Inspect the intersections of cable routes with highways, ditches and ditches;

Inspect the condition of devices and cables laid across bridges, dams, overpasses and other similar structures;

In places where cables exit to the walls of buildings or supports of overhead power lines, check the presence and condition of cable protection from mechanical damage, the serviceability of end couplings;

When inspecting cable lines laid in cable structures, you must:

Check the condition of the anti-corrosion coatings of the metal sheaths of the cables;

Measure the temperature of cable sheaths;

Check the external condition of couplings and end seals;

Check whether there are any displacements or sagging of the cables, whether the distances between the cables provided for by the PUE are observed;

Check the presence and correctness of cable markings;

Check that the lighting is working properly;

Measure indoor air temperature;

Check the serviceability of alarm and fire extinguishing devices;

Check to see if groundwater and wastewater are penetrating, and if there is any industrial waste.

Check the condition of cable wells;

Check the condition of the end sections and end couplings of cable lines entering switchgear of power plants and substations.

Cables with paper and plastic insulation with voltages above 1000 V that are in operation must be periodically subjected to preventive tests with a rectified voltage equal to five times the rated voltage for 5 minutes. This test voltage is sufficient to identify weak points in the cable and couplings. (For example: the electrical strength of good insulation of a 6 kV cable is 200 - 250 kV).

Preventive tests reveal 70 - 85% of defects, the remaining 30 - 15% lead to shutdown of operating lines. They also protect the network from widespread damage due to surges.

The frequency of preventive tests is set from once a year to once every three years. Cables used in more severe conditions are tested more often.

It has been established that the breakdown voltage with negative polarity is 5 - 10% lower than with positive polarity. Therefore, when testing with rectified voltage, it is recommended to connect the negative pole of the source to the core being tested, and the positive pole to connect it to the metal sheath and ground it.

During testing, the cable ends on the switchgear side are usually not loosened, but are disconnected using disconnectors. In this case, the end sleeve and support insulators are tested simultaneously with the cable. In some cases, to save time, it is advisable to simultaneously test several cables connected in series in a chain. In this case, together with the cables, the transformer substation switchgears included in the chain are tested, however, all transformers (power and voltage) must be disconnected.

It is convenient to simultaneously test parallel cables connected to one unit (transformer, switch, etc.). These cables usually have a cross-section greater than 150 mm2. Their disconnection and reattachment is associated with bending and possible damage to the insulation of the end couplings.

Acceptance of cable lines into operation is the final stage of work on their laying and installation. After completion of installation work, when the power cable and couplings are no longer available for direct inspection, acceptance of cable lines is carried out only during electrical testing. However, existing electrical testing methods do not allow identifying all defects in a laid line. Therefore, the reliability of the cable line in operation can be

ensure only if during the construction of the line the rules for laying and installing couplings are not violated.

The installed power cable to be put into operation must be designed to comply with the environmental conditions and the accepted installation method. Uninterrupted operation of a cable line largely depends on the correctly selected type and brand of cable laid.

Acceptance of structures along the cable line route precedes the laying of power cables in them. By the time cables are laid in underground structures, all construction work is completed. When accepting the construction part of underground structures, they check: the correct location of underground structures, the presence of slopes in them for water drainage, if any. necessary, electric lighting, water pumping and ventilation, compliance of internal dimensions with the project, absence of gas and water, as well as the condition of reinforced concrete structures. In addition, extraneous underground communications left in the underground structure are checked against the design and the correctness of the way they intersect with cable structures, for example, in additional pipe cases, as well as the presence of thermal insulation for heat pipes, etc. The correct laying of block sewer pipes is checked by pulling through a metal a cylinder with a diameter 5 mm smaller than the internal diameter of the pipes being tested.

Check the marks of the manholes (which, with improved coverage of the driveways, should not differ from their marks by more than 1 cm), the presence of locking covers, and embedded parts for fastening the cable when laying the cable. In the roadway, cast iron hatches must be laid on reinforced concrete backing rings.

Checking the quality of work during the installation process consists in determining the depth of cable laying, permissible bending radii, the absence of substances in the soil that corrode the cable sheaths, the clear distances between cables (at least 100 mm), the distances at the intersections and approaches of the laid power cable with railway and tram tracks, district heating pipes, communication cables, etc.; the presence of a sand bed for the cable and cushions, protective coatings, cable reserves in front of the couplings to compensate for the length and appropriate fastenings of the couplings in swampy and soft soils. Mechanical damage especially often occurs on cables when they are pulled in pipes through the streets, as well as when entering buildings. Monitoring strict adherence to coupling installation technology consists of checking the sharp bends of the cores, the dimensions of their cutting, the density of insulation winding, the quality of soldering, as well as the quality of the installation material, the compliance of the cable set, tools and accessories.

Technical documentation, transmitted by the installation organization to the laid line, contains:

technical design of the cable line with all approvals for its installation and deviations from the project, indicating with whom and when these deviations were agreed upon;

a diagram of the executive route, certified by the technical supervision of the electrical network enterprise;

cable factory test reports necessary to verify cable compliance with GOST requirements;

acts of external inspection of cables on reels, necessary to ensure that the laid cable was not damaged during transportation or storage;

results of opening and inspection in the laboratory of samples for cables manufactured by foreign companies, as well as for cables for which there are no factory test reports;

test report for the entire cable line after installation.

The technical documentation also includes; inventory of all cable line elements; drawings of construction structures; cable magazine; the act of transferring the design of the route into reality and the correctness of the alignment work; act of acceptance of the trench and the construction part of cable structures for installation; protocol for heating the cable on drums before laying, if the work was carried out at temperatures below 0 °C; protocol for measuring the grounding resistance of end couplings; act for hidden work.

The act for hidden work reflects the following:

inspection of the laid cable;

arrangement of “bed”, “pillow”, protection of the cable line from mechanical damage;

compliance of the dimensions of mutual proximity and intersection with other underground utilities;

installation of all couplings.

If the design for the cable line included measures to electrically protect the metal sheaths of the cable from corrosion, then upon commissioning of the line, protocols must be submitted confirming the correct operation of the protective anti-corrosion devices.

Before turning on the laid cable line, a minimum amount of start-up testing is performed, which consists of determining the integrity of the cable cores, measuring the insulation resistance between the cable cores and between the cores and the ground, testing the cable line with high voltage rectified current and checking the operation of the anti-corrosion protection devices installed on the line against stray currents. currents At the same time, the correct correspondence of the cores in phases from both ends of the line is checked, regardless of their color.

REPAIR OF CABLE AND CABLE LINES

1. GENERAL INSTRUCTIONS FOR CABLE REPAIR

During operation cable lines For certain reasons, cables, as well as couplings and terminations, fail.

Main causes of damage cable lines voltage 1-10 kV are as follows:

1. Previous mechanical damage - 43%.
2. Direct mechanical damage by construction and other organizations - 16%.
3. Defects in couplings and end seals during installation - 10%.
4. Damage to cables and couplings as a result of ground settlement - 8%.
5. Corrosion of metal sheaths of cables - 7%.
6. Defects in cable manufacturing at the factory - 5%.
7. Violations during cable laying - 3%.
8. Aging of insulation due to long-term use or overloads - 1%.
9. Other and unidentified reasons - 7%.

The average data for the last ten years in the Moscow cable network is presented.

In accordance with the requirements of the “Operating Instructions power cable lines. Part 1. Cable lines with voltage up to 35 kV each cable line must undergo current or capital repairs.

Current repairs can be emergency, urgent and planned.

Emergency repairs This is called repair when, after disconnecting the cable line, consumers of all categories are left without voltage and there is no way to supply voltage via high or low voltage cables, including temporary hose cables, or when the backup line to which the load is transferred is unacceptably overloaded and there is no way further unloading or consumer restriction is required.

Emergency repairs are started immediately and carried out continuously in the shortest possible time and turn on the cable line and work.

In large city ​​cable networks and at large industrial enterprises, for this purpose, emergency recovery services have been formed from a team or several teams, which are on duty around the clock and, at the direction of the dispatch service, immediately go to the scene of the accident.

Urgent repairs This is called a repair when receivers of the first or especially important second category are deprived of automatic backup power, and for receivers of all categories, the load on the remaining cable lines causes their overload or limitation of consumers. To urgent cable line repair Repair teams begin at the direction of the energy service management during the work shift.

Scheduled repairs- this is the repair of all cable lines not listed above, which is carried out according to a schedule approved by the management of the energy service. Cable line repair schedule compiled monthly based on entries in walk-through and inspection logs, test and measurement results, as well as data from dispatch services.

Major repairs of cable lines is carried out according to an annual plan, developed annually in the summer for the next year based on operational data.

When drawing up a capital repair plan, the need to introduce new, more modern types of cables and cable fittings is taken into account. It is planned to repair cable structures and all work related to the serviceability of lighting, ventilation, fire-fighting equipment, water pumping devices. The need for partial replacement of cables in certain areas that limit the capacity of lines or do not meet the requirements of thermal resistance in changed operating conditions of the network with increased currents is also taken into account short circuit

Repair of existing cable lines is carried out directly by the operating personnel themselves or by the personnel of specialized electrical installation organizations.

When repairing existing cable lines, the following work is performed:

Preparatory - disconnecting the cable line and grounding it, familiarizing yourself with the documentation and clarifying the brand and cross-section of the cable, issuing a safety permit, loading materials and tools, delivering the team to the work site;

Preparation of the workplace - making pits, excavating pits and trenches, identifying the cable to be repaired, fencing the workplace and excavation sites, identifying the cable in the distribution center (TP) or in cable structures, checking the absence of flammable and explosive gases, obtaining a permit for hot work;

Preparation for installation - admission of the team, puncturing the cable, cutting the cable or opening the coupling, checking the insulation for moisture, cutting off sections of damaged cable, setting up a tent; laying a repair cable insert;

cable joint repair- cutting of cable ends, phasing of cables, installation of couplings (or couplings and terminations);

Registration of the completion of work - closing the doors of the switchgear, transformer substations, cable structures, handing over keys, backfilling pits and trenches, cleaning and loading tools, delivering the team to the base, drawing up an as-built sketch and making changes to the cable line documentation, report on the completion of repairs;

Cable line measurements and tests.

In order to speed up repair work on cable lines, mechanization should be widely used when performing excavation work: pneumatic jackhammers, electric hammers, concrete breakers, excavators, means for heating frozen soil.

Special mobile cable workshops are used to transport repair crews

Cable line repairs There are simple ones that do not require much labor and time, and complex ones when the repair lasts several days.

Simple repairs include, for example, repairs to external covers (jute cover, PVC hose), painting and repair of armor tapes, repair of metal shells, repair of end seals without dismantling the housing, etc. The listed repairs are carried out in one shift by one team (unit).

Complex repairs include those when it is necessary to replace large lengths of cable in cable structures with preliminary dismantling of the cable that has failed, or to lay a new cable in the ground over a section several tens of meters long (in rare cases, hundreds of meters).

Repairs are complicated in most cases by the fact that the cable route passes through complex sections with many turns, with the intersection of highways and utility lines, with a large depth of cable, and also in winter, when it is necessary to warm the ground. When performing complex repairs, a new section is laid cable (insert) and two couplings are mounted

Complex repairs are carried out by one or several teams, and, if necessary, around the clock, using earth-moving mechanisms and other means of mechanization.

Complex repairs are carried out either by the energy service of the enterprise (city networks), or with the involvement of specialized organizations for the installation and repair of cable lines.

2. REPAIR OF PROTECTIVE COVERS

Repair of external jute covering. A cable stretched through pipes, blocks or other obstacles, which has stripped off the impregnated cable yarn and the remaining outer covers to the steel armor, must be restored. Repair is carried out by winding with resin tape in two layers with 50% overlap, followed by coating this area with heated bitumen mastic MB 70 ( MB 90).

Repair of PVC hose and sheaths. The first method of repairing a polyvinyl chloride hose or casings is welding, which is carried out in a stream of hot air (at a temperature of 170-200 ° C) using a welding gun with electrically heated air (Fig. 1) or a gas-air gun (Fig. 2). Compressed air is supplied under pressure 0.98-104 Pa from a compressor, compressed air cylinder, portable unit with a hand pump.

Fig 1. Welding gun PS-1 with electrical heating: - nozzle for hot air outlet, 2 - heating air chamber; 3 - fitting for supplying compressed air, 4 - electrical wire

A polyvinyl chloride rod with a diameter of 4-6 mm is used as a welding additive.

Before welding, areas to be repaired must be cleaned and degreased with gasoline, foreign bodies must be cut out with a cable cutter and protruding edges and burrs must be cut off in places where the hose is damaged.

To repair punctures in small holes and cavities, the damage site in the hose or sheath and the end of the filler rod are heated for 10-15 seconds with a stream of hot air, then the jet is withdrawn, and the end of the rod is pressed and welded to the hose at the heating site. After cooling, making sure that the welding of the rod is strong by lightly tugging it, the rod is cut off.

To seal and level the weld seam, the repair area is heated until signs of melting appear, after which a piece of cable paper folded in three or four layers is pressed onto the heated area by hand. For reliability, the operation is repeated 3-4 times.

To repair a hose or shell that has cracks, slits and cutouts, the end of the filler rod is welded to the entire area of ​​the hose at a distance of 1-2 mm from the damage site.

After making sure that the welding is strong, direct the air stream so that the lower part of the filler rod and both sides of the slot or slot are simultaneously heated. By pressing lightly on the rod, the latter is laid and welded along the crack or slot. Welding of the rod is completed in its entirety at a distance of 1-2 mm from the damage. Then the protruding surfaces of the rod are cut off with a knife and the welded seam is leveled.

Hose or sheath ruptures are repaired using polyvinyl chloride patches or cut cuffs.

The patch is made of plastic so that its edges overlap the tear site by 1.5-2 mm. The patch is welded along the entire perimeter to the hose, and then a filler rod is welded along the resulting seam, and the protruding surfaces of the rod are cut off and the seam is leveled at the welding site.

To repair a hose or sheath using a split cuff, cut off a piece of polyvinyl chloride tube 35-40 mm longer than the length of the damaged area, cut the tube lengthwise and put it on the cable symmetrically to the damaged area. The cuff is temporarily secured with polyvinyl chloride or calico tape with a pitch of 20-25 mm, the end of the rod is welded at the junction of the cuff with the hose (sheath), and then the rod is laid and welded around the end of the cuff. After welding both ends of the cuff to the hose (shell), remove the temporary fastening tapes, weld the rod along the cut of the cuff, cut off the protruding surfaces of the rod and make the final alignment of all welds.

According to the second method repair of PVC hoses and cable sheaths can be performed using epoxy compound and glass tape. The surface of the hose or sheath is pre-treated as indicated above, and additionally roughness is created on it using a hog file. The place of damage and beyond its edges at a distance of 50-60 mm in both directions is lubricated with epoxy compound K-P5 or K-176 with hardeners introduced into it. Four to five layers of glass tape are applied over the layer of epoxy compound, each of which is also coated with a layer of compound.

Temporary repairs to hoses and casings to prevent
penetration of moisture under the shell cable, and also to prevent the bitumen composition from leaking out from under the hose, it is allowed to carry out using adhesive polyvinyl chloride tape with a 50% overlap in three layers with the top layer coated with polyvinyl chloride varnish No. 1. According to the second method, temporary repairs are carried out with LETSAR tape in three layers with 50 % overlap.

Painting armor tapes. If, during inspections of cable structures on openly laid cables, damage to the armored covering of the cable is detected by corrosion, they are painted. It is recommended to use heat-resistant pentaphthalic varnishes PF-170 or PF-171 (GOST 15907-70*) or heat-resistant oil-bitumen paint BT-577 (GOST 5631-79*).

The best way to paint is to use a spray gun, or, if it is not available, a brush.

Repair of armor tapes. On openly laid cables, detected sections of destroyed armor tapes are cut off and removed. Temporary bandages are made in places where the tapes are cut. Next to the temporary bands, both tapes are carefully cleaned to a metallic shine and served with POSSu 30-2 solder, after which the grounding wire is secured with bands of galvanized wire with a diameter of 1-1.4 mm and soldered with the same solder. The cross-section of the grounding conductor is selected depending on the cross-section of the cable cores, but not less than 6 mm2.

When tinning and soldering armored tapes, solder fat is used. The duration of each soldering should be no more than 3 minutes. Temporary bandages are removed. An anti-corrosion coating is applied to the exposed area of ​​the shell.

In cases where mechanical impacts are possible on the cable section being repaired, one layer of armor tape is additionally wound around it, which is previously removed from the cable section with intact armor. The tape is wound with 50% overlap and secured with galvanized wire bands. In this case, the grounding conductor must be fluffed out along the entire length of the jumper in order to create a tight fit of the armor around the section of the cable being repaired

3. REPAIR OF METAL SHELLS

At damage to the cable sheath(cracks, punctures), when there is a leak of oil-rosin composition in this area, the sheath is removed from the cable on both sides of the damage site at a distance of 150 mm from the damage site. The top layer of the belt insulation is removed and checked for moisture in heated paraffin.

If there is no moisture and the insulation is not destroyed, the lead or aluminum sheath is repaired.

A strip 70-80 mm wider than the bare section of the cable and 30-40 mm longer than the circumference of the cable along the sheath is cut out of sheet lead 2-2.5 mm thick. Two filling holes are made in the strip so that they are located above the exposed part of the cable. The strip is thoroughly cleaned of dust and dirt with a rag soaked in gasoline.

The removed semiconductive layer of paper and the top tape of the waist insulation are restored and secured with bandages made of cotton threads. The area is scalded with MP-1 cable mass.

A strip of lead is wrapped around the bare part of the cable so that it extends evenly to the edges cable sheath, and the edges of the resulting lead pipe overlapped each other by at least 15-20 mm. First, the longitudinal seam is soldered with POSSU 30-2 solder, and then the ends of the pipe are bent to the cable sheath and soldered to it.

For cables with an aluminum sheath, in the place where the lead pipe is soldered, the cable sheath is served with grade A solder. The coupling is filled with hot cable mass MP-1. After cooling and topping up, the filling holes are sealed. A bandage of copper wire is applied to the soldered area at the ends, turn to turn with a diameter of 1 mm with an outlet of 10 mm to the cable sheath and is soldered to the sheath. The repaired area is covered with resin tape in two layers with 50% overlap.

In the event that moisture has penetrated under the sheath or the belt insulation is damaged, as well as the core insulation, the section of cable is cut out along the entire length where there is moisture or damage to the insulation. Instead, a piece of cable of the required length is inserted and two connecting couplings are installed. The cross-section and voltage of the cable must correspond to the cut section.

You can use a different brand of cable for insertion, but its design is similar to the cut section.

4 RESTORATION OF CABLE PAPER INSULATION

In cases where the current-carrying conductors are not damaged, but the conductor insulation and belt insulation are damaged, but there is no moisture in it, the insulation is restored, followed by the installation of a split lead coupling.

The cable is excavated to such a length that it is possible to create sufficient slack in the cable to separate the cores from each other. After dividing the conductors and removing the old insulation, the insulation of the conductors is restored by applying paper rollers or LETSAR tape with pre-treatment with MP-1 scalding mass. A split lead coupling is installed and the longitudinal seam is first soldered, and then the coupling is soldered to the cable sheath.

This repair can be performed on horizontal sections of cable routes, where there is no increased oil pressure, since a coupling with longitudinal soldering has less mechanical strength.

5. REPAIR OF CURRENT-CONDUCTING CABLE CORES

If the cable cores break at a small length and it is possible to tighten the cable due to the “snake” made during installation, the usual repair of the lead or epoxy coupling is carried out. In the event that there is no supply of cable, extended connecting sleeves and couplings can be used. Repair in this case is carried out with one lead coupling. In all other cases, when repairing current-carrying cable cores, a cable insert is used and two lead or epoxy couplings are installed.

6. REPAIR OF CONNECTING COUPLINGS

Necessity coupling repair or the installation of the cable insert and two couplings is installed after inspecting the coupling and disassembling it.

In the event that a breakdown occurs from the soldering point of the conductor or from the sleeve to the body of the lead coupling and the destruction from the breakdown is small in size and the insulation is not moistened, the coupling is sequentially disassembled and the damaged part of the insulation is disassembled. Then the insulation is restored with paper rollers or LETSAR tape and scalded with mass MP-1. The split coupling body is installed, and all further operations for assembling the coupling are performed.

If a breakdown occurs in the neck of the coupling from the core to the edge of the shell and the insulation is not moistened, the coupling is disassembled. Then a section of the armor and sheath is cut to the length necessary for convenient separation of the cores. The insulation of the damaged core is restored and scalding is performed. The extended split lead coupling body is installed and all coupling installation operations are performed.

If it is impossible to make an extended coupling due to large damage, then cable insertion is used with the installation of two couplings according to the technology provided for in the technical documentation.

In most cases, damage to couplings occurs during preventive tests with increased voltage. And if repairs are not started immediately after determining the location of the damage, moisture begins to enter the coupling. In this case, repair of the damaged coupling is carried out by cutting out the defective coupling and cable sections. As a rule, the longer a damaged and unrepaired coupling lies in the ground, the longer the cable insertion has to be made for restoration when repairing a cable line.

7. REPAIR OF END COUPLINGS FOR OUTDOOR INSTALLATION

Outdoor terminations in most cases, they fail to work during rainy periods of the year or at high relative humidity and, as a rule, have large defects and destruction inside the coupling. Therefore, the damaged coupling is cut off, the cable insulation is checked for moisture, and if the paper insulation is not moistened, the coupling is installed in accordance with the requirements of the technical documentation. If the cable length at the end of the line has sufficient margin, then repairs are limited to installing only the end coupling. If the cable supply is not enough, then a cable of the required length is inserted at the end of the cable line. In this case, it is necessary to install connecting and end couplings.

Dismantled couplings can be used for re-installation. But to do this, it is necessary to clean the housing and all parts of the coupling from soot, wash them with gasoline and dry them.

IN outdoor terminations with a metal body, check the seals and tighten the nuts once a year during the entire period of operation. At the same time, inspect the contact connections and, if necessary, clean the contact surfaces and tighten the bolts.

Systematically (as needed according to the inspection results) the soldering areas, reinforcement seams and seals are painted with XB-124 enamel.

The surface of epoxy end couplings for outdoor installation must be painted with air-drying enamels EP-51 or GF-92HS during operation (once every 3-5 years, depending on local conditions). Painting is carried out in dry weather, having previously cleaned the surface of the coupling and insulators

The insulators of the terminations of external and internal installations, as well as the insulating surfaces of the terminations, must be periodically cleaned of dust and dirt with a lint-free cloth moistened with gasoline or acetone. Cable termination fittings in workshops of industrial enterprises and areas with conductive conductive materials should be cleaned more frequently. dust

The frequency of wiping and cleaning the cable end fittings at a given electrical installation is determined by the chief engineer of the local power company.

8. REPAIR OF END SEALS

If the termination body is destroyed and the cores in the spine are burnt out, the repair of the terminations is carried out in the same way as the repair of end couplings, with the exception that the termination body and parts cannot be reused.

End seal repair in steel funnels, when the insulation of the cores is destroyed, it is carried out in the following sequence - the destroyed insulation of the cores or that has become unusable (contamination, moisture) is removed from the cores, one layer of paper insulation is rolled up, winding is carried out in five layers with a 50% overlap with adhesive polyvinyl chloride tape or three layers of rubberized tape followed by coating with insulating tapes or paints. Instead of the indicated tapes, repairs can be performed using LETSAR tape (two layers) and PVC tape (one layer).

In case of cracking, peeling, partial failure and significant contamination of the filling composition, especially when these defects are accompanied by a noticeable displacement of the cores between themselves or towards the funnel body (which can in turn be caused by an incorrect position or absence of a spacer plate), the steel funnel should be completely refilled.

The old filling compound is removed (melted), the funnel is lowered down and cleaned of soot and dirt. A new seal is rolled up (under the funnel), and the funnel is put in place.

The neck of the funnel is wrapped with resin tape, and the funnel along with the cable is attached to the supporting structure with a clamp. The correct position of the porcelain bushings is checked. The funnel is filled with a filling compound (MB-70, MB-90).

Repair of PVC tape end seals is carried out in the presence of an impregnating composition in the spine or on the cores, in case of cracking and breaks of the tapes.

The repair technology consists of dismantling old tapes and winding new PVC or LETSAR tapes on the cores.

Epoxy End Seals Repair if the windings on the cores are destroyed, it is carried out with the dismantling of old tapes, restoration of new LETSAR tapes and additional filling of epoxy compound so that the tapes extend into the poured compound by at least 15 mm.

When the impregnating composition flows through the cable in the root of the seal, the lower part of the seal in a section of 40-50 mm and at the same distance the section of armor or sheath (for unarmored cables) are degreased. A two-layer winding made of cotton tape lubricated with an epoxy compound is applied to the grease-free section of the termination body and the adjacent cable section 15-20 mm wide. A repair mold is installed (Fig. 3), which is filled with epoxy compound.

Rice. 3. Installation of a repair form to eliminate leakage of the impregnating composition at the point where the cable enters the termination body:
1 - seal body, 2 - repair form; 3 - leak location

Rice. 4. Installation of a repair form to eliminate a leak at the point where the cores exit the casing:
1 - repair form; 2 - leak location, 3 - seal body

If the tightness is broken at the point where the conductors exit the termination body, the upper flat part of the termination body and sections of tubes or winding of conductors 30 mm long adjacent to the housing are degreased. A removable repair form is installed (Fig. 5 4), the dimensions of which are selected depending on the standard size of the seal. Filling the mold with the compound is done in the same way as in the previous case.

If the tightness on the conductors is broken, the defective section of the tube or conductor winding is degreased and a repair is applied.

Two-layer winding made of cotton tapes with generous coating of each turn of the winding with epoxy compound or LETSAR tape in three layers.

If the tightness at the junction of the tube or winding with the cylindrical part of the tip is broken, the surface of the bandage and the section of the tube or winding of the core with a length of 30 mm are degreased. A two-layer winding of cotton tapes is applied to the fat-free areas with a generous coating of compound on each turn of the winding. A dense bandage of twisted twine is placed on top of the winding and also coated with an epoxy compound.

The operating organization must carry out technical supervision during the laying and installation of cable lines that are newly constructed by other organizations and then transferred to the balance sheet of the power system.

The presence of a representative of the operating organization during the performance of work does not relieve the installation organization and the work contractor of responsibility for the work they perform. The laying and installation of cable lines of all voltages is permitted only to persons who have undergone special training, passed exams and received a certificate to perform the specified work.

The person performing technical supervision is obliged to familiarize himself with the design of the laying and installation of the cable line, before laying it, check the condition and quality of the cables on the drums, as well as cable couplings and installation materials using documents and inspection, check the quality of work during the laying and installation of the cable line and the correctness of the markings.

The person performing technical supervision is obliged to notify the work manufacturer of all noticed defects and violations and demand their elimination.

If there are disagreements with the work manufacturer, the person performing technical supervision must notify his administration about this. The newly installed cable line must be accepted into operation by a commission consisting of representatives of the installation and operating organizations. The head of the operating organization is appointed as the chairman of the commission.

The commission for acceptance of the cable line into operation is obliged to check the technical documentation, inspect the cable line route, check the work performed (hidden work is checked selectively, if necessary), and also familiarize itself with the results of testing the cable line.

When accepting a newly constructed cable line into operation, tests and measurements must be carried out in accordance with the “Electrical Equipment Testing Standards”.

When putting the cable line into operation, the documentation provided for in the PTE and SNiP must be presented.

Acceptance of a cable line into operation is formalized by an act which states:

• -name of the organization that carried out the construction and installation of the cable line;
• - surname of the work manufacturer;
• - the name of the operation representative who observed the work;
• - name and purpose of the line and place of laying;
• - brief description of the line (cable brand, cross-section, voltage, length, type of coupling and terminations, their number, etc.);
• - compliance of the work performed with current rules and regulations;
• - conclusion on the suitability of the line for operation.

All documents and their inventory are attached to the act, as well as a copy of the order appointing persons responsible for the safety of the cable route passing through the territory of the enterprise.

In accordance with the requirements of the PUE, the scope of acceptance tests of power cable lines includes the following work.

• 1. Checking the integrity and phasing of the cable cores.
• 2. Insulation resistance measurement.
• 3. Test with increased voltage of rectified current.
• 4. Power frequency high voltage test.
• 5. Determination of the active resistance of the cores.
• 6. Determination of the electrical working capacitance of the cores.
• 7. Measurement of current distribution along single-core cables.
• 8. Checking protection against stray currents.
• 9. Test for the presence of undissolved air (impregnation test).
• 10. Testing of feeding units and automatic heating of end couplings.
• 11. Monitoring the condition of the anti-corrosion coating.
• 12. Checking oil characteristics.
• 13. Ground resistance measurement.

Power cable lines with voltage up to 1 kV are tested according to clauses 1, 2, 7, 13. Power cable lines with voltage above 1 kV and up to 35 kV - according to clauses 1-3, 6, 7, 11, 13, and with a voltage of 110 kV and above - in full, provided for by these instructions.

Before putting the cable into operation, its phasing is carried out, i.e. ensures that the cable phases correspond to the phases of the connected section of the electrical installation. The test is carried out by dialing using telephone handsets or a megohmmeter. Based on the inspection, the cores are colored in accordance with the coloring adopted at this installation.

The technology of “dialing” using telephone handsets is as follows: one worker connects his telephone handset to the cable core and sheath (the grounded part of the electrical wiring), and the other, one by one, to the cable cores on his side until he reaches the core to which the first one connected worker.

In this case, a telephone connection is established between the workers and they can agree on the procedure for checking another core. Temporary tags with appropriate markings are hung on the inspected cores. Testing the cores by “continuity” will be successful if the possibility of bypass circuits is excluded. To avoid errors, you must make sure that communication is possible only over one core; To do this, connect the tube to each of the remaining wires and make sure that there is no connection through them.

For dialing, low-impedance telephone handsets are used, and a flashlight battery is used as a power source.

After preliminary testing, before putting the cable line into operation, it is phased under voltage. To do this, operating voltage is supplied from one end of the cable, and from the other end the phase correspondence is checked by measuring voltages between like and unlike phases.

Carbonation is produced using voltmeters (in networks up to 1 kV) or voltmeters with voltage transformers, as well as using voltage indicators such as UVN-80, UVNF, etc. (in networks with voltages above 1 kV),

The order of phasing in lines of different voltages is approximately the same. Thus, phasing of a cable line using voltage indicators is performed in the following sequence (see Fig. 21). The serviceability of the voltage indicator is checked, for which the probe of the tube without a neon lamp touches the ground, and the probe of the other tube is brought to the core of the energized cable, and the neon lamp should light up. Then the probes of both tubes touch one live wire. The indicator lamp should not light up. After this, the presence of voltage is checked at the terminals of the electrical installation and cable (see Fig. 21c). This check is carried out in order to exclude an error in the phasing of a line that has an open circuit (for example, due to a faulty fuse). The process of phasing itself consists in the fact that the probe of one indicator tube touches any extreme terminal of the installation, for example, phase C, and the probe of another tube touches alternately three terminals from the side of the line being phased (see Fig. 21d). In two cases of contact (C-A 1 and C-B1) the neon lamp lights up, in the third (C-C1) the paw will not light up, which will indicate the same phases. Other phases of the same name are defined similarly.

Insulation resistance is measured with a megohmmeter for a voltage of 2.5 kV. For power cables up to 1 kV, the insulation resistance must be at least 0.5 MOhm. For power cables above 1 kV, the insulation resistance is not standardized, but it should be about a dozen megohms or higher. The measurement should be made before and after testing the cable with increased voltage.

The method for measuring resistance and the instruments used for this are presented testing the insulation of electrical equipment with increased voltage.

Before starting to measure the insulation resistance on a cable line, you must:

• 1. Make sure there is no voltage on the line.
• 2. Ground the circuit under test while connecting the device.

a, b - checking the serviceability of the voltage indicator; c - checking the presence of voltage at the terminals; g - phasing.

Figure 21 - Sequence of operations when phasing a 10 kV line with a voltage indicator of the UVNF type

After completing the measurement, before disconnecting the ends from the device, it is necessary to remove the accumulated charge by applying grounding.

The cable must be discharged using a special discharge rod, first through a limiting resistance, and then short-circuited. Short cable sections up to 100 m long can be discharged without limiting resistance.

When measuring the insulation resistance of long cable lines, it must be remembered that they have significant capacitance, so the megohmmeter readings should be noted only after the cable has been charged.

Page 32 of 42

Chapter XI. Operation and repair of cable lines

§ 46. Acceptance of cable lines and structures into operation

Acceptance of cable lines into operation is carried out after completion of cable laying and installation of connecting and end couplings. All work is carried out in accordance with the approved and agreed upon project, the Gosstroy instructions for laying cables with voltages up to 110 kV (SN 85 - 74) and the current technical documentation for couplings for cables with paper and plastic insulation.

Upon acceptance into operation, cable lines are subject to inspection and electrical tests. Hidden cables (in trenches, blocks, etc.) cannot be inspected after all work on the routes has been completed, and existing electrical testing methods do not make it possible to identify all defects in the laid line. Therefore, in order to ensure good quality of work, it is necessary to control the cable laying and installation of couplings during their production, i.e., carry out technical supervision.

Technical supervision includes: inspection of cable structures and trenches; familiarization with factory test reports of the cable and its condition; checking the quality of work during cable laying and installation of couplings; control over whether installation personnel have certificates allowing them to perform the specified work. It is carried out by the organization that will operate the laid cable.

Trenches, channels, tunnels and other cable structures are made taking into account the minimum permissible radii and bends of the cables given in Table. 16.

Table 16. Minimum permissible bending radii of cables during installation

Note. DK is the outer diameter of the cable.

When inspecting cable structures, the following must be checked: the presence of slopes for water drainage, electric lighting, ventilation and water pumping, compliance of internal dimensions with the design, condition of reinforced concrete structures, etc.

Checking the quality of work when laying cables includes: monitoring the tensile force of the cable using a dynamometer; determination of permissible bending radii, laying depths and distances between parallel laid cables, as well as distances between the outermost cables and the walls of structures; determination of distances at intersections and approaches of cables with various structures; control over the presence of a sand cushion under the cable, protective coatings, cable reserves in front of the couplings, and marking tags.

Control over the installation of couplings includes checking: compliance of the standard size of the coupling with the cable cross-section; availability of quality and not expired (expiration date) component materials; availability of appropriate tools and devices; compliance with the mandatory technology and installation sequence.

The marking tags indicate their brand, rated voltage, number and cross-section of cores, number or name of the cable line. On the labels of power cable couplings, in addition, indicate the date of installation and the name of the electrician-cable fitter; and on the end seal labels - the end points (where the cable is laid from and to).

Cables after laying, installation of cable couplings and end seals, installation of end seals (in the cable compartment of the switchgear, etc.) are tested according to the standards provided for by the PUE.

Simultaneously with the tests, the compliance of the cores in phases of both ends of the line is checked, regardless of their colors: the PUE establishes the order of alternating colors of the phases of the switchgear buses. Phase L1 tires are painted yellow, phase L2 - green, phase L3, - red, and zero working bus N- blue color, insulation of cable line cores - according to the colors of the buses to which they are connected.

After switching on the cable line under voltage, the devices check the phasing, which consists in determining the same phases of the cable core and the connected bus. If the voltage difference between the cable core and the same phase of the switchgear bus is zero, this means phase matching; if it is not zero, this means phase mismatch and incorrect cable connection. Inserting such a cable into a main circuit may cause a short circuit. For phasing cable lines with voltages of 6 and 10 kV, 10 kV voltage indicators are used, complete with additional resistance (Fig. 112).

Rice. 112. Phasing of cable lines:
A -correspondence of the phase of the cable and the bus b - mismatch of the phase of the cable and the bus at the connection points; 1 - voltage indicator, 2 - wire, 3 - resistance tube, 4 - tires, 5 - tire deflation connector, 6 - end seal, 7 - cable; F - yellow, 3 - green, K - red tires

Documentation for putting cable lines into operation. The technical documentation includes a cable line project with changes, deviations and instructions with whom and when they were agreed upon.

The plan of a cable line laid in a trench shows: coordinates of connecting couplings tied to existing permanent buildings or special identification marks; cable line diagram indicating the serial numbers of the drums of the laid cables and their length; sequence of laying drums and numbering of couplings when laying cables in a trench; materials for coordinating the cable line route. In addition, acts are provided: acceptance of trenches and cable structures for installation; for hidden pipe laying work; inspection of cables on drums before installation and reports of their factory tests; inspection of cable ducts in trenches and channels before closing; logs of cable laying and cutting of cable couplings with voltages above 1000, as well as protocols for heating cables on a drum before laying at low temperatures and electrical tests of power cables after installation.

All the above acts and protocols are entered into a general statement, which is presented along with the documentation upon delivery. Acceptance of the cable line into operation is carried out according to the act.