The type of operational maintenance of the electrical installation, the number of workers from among the operational personnel in a shift is determined by the management of the structural unit and is fixed by the corresponding order. Work in electrical installations and on electrical equipment is carried out according to a permit (hereinafter referred to as the outfit), by order, according to the list of works performed in the order of current operation.
3.2.1.1. In the order of current operation, only those works are carried out that are approved in the list of works in the order of current operation.
3.2.1.2. By order, the following are carried out:
Stress relief work:
Power supply connection for electrical installations with voltage up to 1000 V;
Replacement of elements and parts, measuring devices on high-voltage power supply, relay panels, racks of the automatic voltage regulation system;
Cleaning of devices, installation of circuit breakers, switches, magnetic starters, checking the reliability of contactors on circuit breakers, clamps, lugs switchgears alternating and direct current of all types;
Work without relieving stress:
Cleaning, outside inspection of power and relay input panels, racks and remote power boards, automatic voltage regulation systems, AC and DC switchboards and panels and other switchgear;
Replacement of 15 - 100 A fuses in lightning protection devices (GZA) on the lead-in boards.
3.2.1.3. The right to issue orders and orders for the distance is granted to administrative and technical personnel who have an electrical safety group of at least IV.
3.2.1.4. For each workplace where work is performed alongside, a technological map for the preparation of the workplace is developed, approved by the person in charge of the electrical equipment.
3.2.1.5. Technological maps of workplaces related to the provision by the energy supplying organization are agreed with the energy supplying organization.
3.2.1.6. Operational and repair personnel of the distance, solely servicing electrical installations (senior electromechanic, electromechanic, site manager, etc.), must have at least Group III for electrical safety.
At the workplace of the operating personnel, there must be a list of persons of electrical personnel who have been granted the right to solely inspect electrical installations, approved by the person responsible for the electrical equipment.
3.2.1.7. Before starting work on the guaranteed power supply panel, the supervisor must agree with the energy dispatcher on the place, content and categories of work.
3.2.1.8. An internal check of the guaranteed power supply board should be carried out with the voltage removed at the main and reserve feeders. Voltage relief is performed by employees of the power supply distance.
3.2.1.9. Housings of shields, cabinets, assemblies must be grounded. The necessity and possibility of grounding the connections of these shields, assemblies and the equipment connected to them is determined by the issuing order or order.
Operations for the installation and removal of grounding are allowed to be performed by one worker from among the operating personnel.
3.2.1.10. Before performing work in the ASU, it is necessary to make sure that the protective grounding of the ASU case is in good condition. To do this, first of all, it is necessary to make sure of the integrity of the conductor by visual inspection. It is necessary to check the absence of voltage with a voltage indicator. The serviceability of the voltage indicator before its use must be established by means of special devices intended for this purpose or by approaching live parts located nearby and knowingly under the appropriate voltage. If the checked voltage indicator has been dropped or subjected to jolts (impacts), then it is prohibited to use it without re-checking.
3.2.1.11. Control of the integrity of the grounding must be carried out with dielectric gloves lightly wiggling the grounding conductors connected to the ASU body.
3.2.1.12. Before opening the outer door of the switchgear, make sure there is a dielectric mat on the floor.
3.2.1.13. The voltage value is monitored by indicators built into the panel board. The measurement results should be recorded in the power supply inspection log.
3.2.1.14. Control switching of power supply feeders must be carried out with dielectric gloves using power supply switching machines. Each time one of the machines is disconnected, the circuit for switching the power supply to the other feeder should be automatically triggered.
3.2.1.15. Cleaning the internal elements from dust and dirt is carried out with a dry brush, and the external surfaces of the cabinets with a dry cloth or rag, without touching the metal parts with your hands.
3.2.1.16. Cleaning the contacts of the switches from carbon deposits and dirt should be carried out with dielectric gloves using an insulating tool, with the voltage removed.
3.2.1.17. When performing work without removing the voltage on live parts using insulating protective equipment, it is necessary:
Hold the insulating parts of the protective equipment by the handles up to the stop ring;
Position the insulating parts of the protective equipment so that there is no danger of overlapping on the surface of the insulation between the live parts of two phases or a ground fault;
Use only dry and clean protective equipment with undamaged varnish coating.
If a violation of the lacquer coating or other malfunctions of the insulating parts of the protective equipment is found, their use should be stopped immediately.
3.2.1.18. Replacing the fuses in the voltage switchgear must be carried out with the use of insulating tongs (or special devices), with dielectric gloves and with the use of means for protecting the face and eyes.
Replacement should be done slowly and carefully. First, a test movement is made with the drive lever in order to make sure that the rods are in good working order, there are no oscillations and breakdowns of the insulators.
3.2.1.19. It is not allowed to use uncalibrated fuses and fuses.
3.2.1.20. In electrical installations, work in a cramped position is not allowed. When working in the immediate vicinity of unshielded live parts, it must not be located so that these parts are at the back or on both sides.
3.2.1.21. When a thunderstorm approaches, all work in the ASU should be stopped.
3.2.1.22. Work on the replacement of circuit breakers located on the internal panel of the new generation ASU (such as SUEP-2, UEPS-2 and their analogs) should be carried out using hand tool with insulating handles (screwdrivers, pliers, etc.) without dielectric gloves. Avoid touching the bare ends of wires suitable for switches, which may be energized by 220 V.
3.2.1.23. The replacement of lighting lamps in the ASU and battery rooms is allowed to be carried out solely by the operating personnel.
3.2.1.24. It is not allowed to individually change lamps from ladders.
3.2.1.25. The premises in which the ASP are located must be equipped with primary fire extinguishing equipment in accordance with the approved standards.
Electricity of the net
Substation service
INSTRUCTIONS
for maintenance of AC panels
Knowledge of this manual mandatory for:
1. The head, master of the substation group.
2. Operational and operational - production personnel of substation groups.
These instructions have been compiled on the basis of the valid:
GKD 34.20.507-2003 Technical operation electrical networks and stations. Rules. Electrical Installation Rules (PUE), ed. 6th, rev. and add. - G .: Energoatomizdat, 1987; DNAP 1.1.10-1.01-97 Rules safe operation electrical installations; GKD 34.20.302-2002 "Standards for testing electrical equipment".
At electrical substations 35 - 110 kV, for power supply of auxiliary mechanisms, units and other consumers of their own needs (s. N.), Rather developed wiring diagrams are used. The main consumers of their own needs are: operating circuits of alternating and rectified current; cooling system for transformers; on-load voltage regulation devices (OLTC); battery charging and recharging units; lighting (emergency, indoor, outdoor, security); communication and telemechanics devices; pumping units(fire extinguishing, household, technical water supply); electric heating devices for storage batteries, switches, separators and their drives, KRUN, various cabinets outdoor installation; distillers, ventilation, etc.
Figure # 1. Connection diagram for auxiliary needs in the presence of alternating and rectified operating current at the substation.
When choosing wiring diagrams, measures are provided to increase their reliability: installation of at least two transformers at the substation with. n. (usually no more than 560 or 630 kVA); sectioning of auxiliary buses; the use of automatic transfer switch (ATS) on the sectional switch; redundancy on the high voltage side (s. n.), etc.
Figure 1.2 shows the diagrams with. n. substations used depending on the type of operating current. With alternating and rectified current, a circuit is recommended (Fig. 1), according to which the direct connection of transformers with. n. to the low voltage windings of the main transformers. This connection provides power to the operating current network and the operation of circuit breakers when the 6-10 kV buses are disconnected. With a constant operating current, the circuit shown in Fig. 2 when transformers with. n. directly connected to buses 6-10 kV.
Figure # 2. Connection diagram for auxiliary needs in the presence of constant operating current at substations.
Usually one or two transformers are installed at substations. n., but in the presence of particularly responsible consumers, a reserve transformer for auxiliary needs can be provided.
At 110 kV substations and powerful 35 kV substations, two auxiliary transformers are normally installed, connecting them to the secondary voltage buses of 6-10 kV of the substation. Figure 3 shows the connection of a working (standby) auxiliary transformer, of which one is normally in operation.
The connection to the busbars of both transformers through one disconnector and one set of fuses is made in order to reduce the number of switchgear bays.
Figure №3. Connection diagram of TSN through one disconnector
If the outgoing lines of the substation are reactive, then the reactors are not installed in front of the auxiliary transformers.
The power of each transformer must be sufficient to cover the normal continuous load of the substation's auxiliary needs. If the operating time of the mechanisms of any two substation facilities coincides (for example, the operation of the mechanisms of the oil economy while charging the battery, etc.), the load must be covered by both transformers.
At small and medium-sized substations without constant duty personnel, there is usually no constant consumption of electricity for their own needs. At such substations, there is only electric lighting, which is used for inspections and repairs.
The power consumed for auxiliary needs of substations usually does not exceed 50 - 200 kW (the latter in the presence of a large transformer repair shop and oil facilities). The power consumption may be slightly higher if there are synchronous compensators at the substation. In a number of cases, the residential community is also supplied from the installation of the substation's own needs. The most important mechanisms for auxiliary needs of substations on alternating current are artificial cooling fans of powerful transformers. All other responsible consumers of auxiliaries of the substation are constantly powered from storage batteries or are backed up from them (like emergency lighting). At substations with installed electromagnetic drives on the high voltage side and in the absence of a storage battery, a transformer is installed on the supply line (Fig. 4).
Figure №4. Substation with one MV transformer.
At relatively small step-down substations of 35 kV with a secondary voltage of 6-10 kV, one transformer with a secondary voltage of 380/220 is installed for auxiliary power supply - Figure No. 4. If necessary, power backup can be carried out from the nearest city or factory network, with the voltage of which the secondary voltage of the auxiliary transformer must be coordinated.
2. Arrangement of boards, alternating current networks up to 1000V.
Switchgears must be clearly labeled to indicate the purpose of the individual circuits and panels. The inscriptions must be on front side of the device, and in case of double-sided service, also on the back of the device.
Parts of the switchgear related to circuits of various currents and different voltages must be made and placed so that they can be clearly recognized.
The relative position of phases and poles within the entire device should, as a rule, be the same. Tires must be painted as specified below:
(Zero working conductor is a conductor used to power electrical consumers, connected to the grounded neutral of the transformer, the neutral protective conductor is a conductor that connects the neutralized parts to the grounded neutral of the transformer).
The switchgear must be provided with the ability to install portable protective earthing.
All metal parts of the switchgear must be painted or have another anti-corrosion coating.
Devices and devices should be located so that sparks or electric arcs arising in them during operation cannot harm the operating personnel, ignite or damage the surrounding objects, cause a short circuit or earth fault.
Chopping devices must be installed so that they cannot close the circuit spontaneously, under the influence of gravity. Their moving live parts in the off state, as a rule, should not be energized.
Switches with direct manual control (without a drive), designed to turn on and off the load current and have contacts facing the operator, must be protected by fireproof covers without holes and slots. The indicated circuit breakers, intended only for stress relief, may be installed openly, provided that they are inaccessible to unqualified personnel.
The actuators of the switching devices must clearly indicate the “on” and “off” positions.
It should be possible to remove the voltage from each circuit breaker during its repair or dismantling. For this purpose, switches or other disconnecting devices must be installed in the necessary places.
The disconnecting device in front of the switch of each line outgoing from the switchgear is not required to be provided in electrical installations:
For these disconnecting devices, a special drive (for example, a lever drive) is not required.
Threaded (plug) fuses should be installed so that the supply wires are connected to the contact screw, and the outgoing wires to the electrical consumers are connected to the screw sleeve.
Between the fixed non-insulated current-carrying parts of different polarity, as well as between them and the non-insulated non-current-carrying metal parts, distances of at least: 20 mm along the surface of the insulation and 12 mm in the air must be provided. From non-insulated live parts to the fences, distances of at least 100 mm with grids and 40 mm with continuous removable fences must be ensured.
Within panels, switchboards and cabinets installed in dry rooms, unprotected insulated wires with insulation rated for an operating voltage of at least 660 V can be laid on metal surfaces protected from corrosion and, moreover, close to one another. In these cases, derating factors for current loads must be applied to the power circuits.
Bare and earthed wires and busbars can be routed without insulation.
The panels' bodies must be made of non-combustible materials, and the structures of the casings and other parts of the devices must be made of non-combustible or hardly combustible materials. This requirement does not apply to control rooms and similar control panels.
Switchgears must be designed so that vibrations arising from the action of the devices, as well as from shocks caused by external influences, do not break the contact connections and do not cause misalignment of the devices and devices.
The surfaces of hygroscopic insulation boards, on which non-insulated live parts are directly mounted, must be protected from moisture penetration into them (by impregnation, painting, etc.).
In devices installed in damp and especially damp rooms and open installations, the use of hygroscopic insulating materials (for example, marble, asbestos cement) is not allowed.
In dusty, damp, especially damp rooms and in the open air, switchgears should be installed that are reliably protected from the negative effects of the environment.
In electrical rooms, service aisles located on the front or rear side of the switchboard must meet the following requirements:
Service passages of panels with a panel length of more than 7 m must have two exits. Exits from the passage from the mounting side of the switchboard can be made both to the switchboard room and to other rooms. If the width of the service aisle is more than 3 m and there are no oil-filled devices, the second exit is not required. Doors from switchgear rooms should open towards other rooms (except for switchgear rooms above 1 kV AC and above 1.5 kV DC) or outward and have a self-locking lock.
The neutral of the transformer on the side up to 1 kV must be connected to the earthing switch using an earthing conductor. The cross-section of the grounding conductor must be at least - 4 mm 2 for copper or 6 mm 2 for aluminum.
The use of a neutral working conductor from the neutral of the transformer to the switchgear panel is not allowed as a grounding conductor.
The output of the neutral working conductor from the neutral of the transformer to the switchgear panel must be performed: when the phases are withdrawn by buses - a bus on insulators, when the phases are withdrawn by a cable (wire) - a core cable (wires).
The conductivity of the neutral working conductor coming from the neutral of the transformer must be at least 50% of the conductivity of the phase output.
The resistance of the grounding device, to which the neutrals of the transformers or the terminals of the single-phase current source are connected, at any time of the year should be no more than 2, 4 and 8 Ohms, respectively, at line voltages of 660, 380 and 220 V of a three-phase current source or 380, 220 and 127 V of a source single-phase current. This resistance must be ensured taking into account the use of natural ground electrodes, as well as ground electrodes for repeated grounding of the neutral wire of overhead lines up to 1 kV with the number of outgoing lines at least two.
3. Maintenance of sources and AC mains.
Maintenance of ATS equipment, switchboards and assemblies of circuit breakers, contactors, fuses is carried out in the same way as the operation of low-voltage electrical equipment.
The insulation resistance in AC circuits, measured with a 1000 V megohmmeter, must be maintained at a level of at least 1 megohm.
Maintenance of AC switchboards must be carried out once every 6-8 years, including revision of contact connections, checking the cross-section of connecting jumpers and busbars.
During maintenance of DC boards (once every 6 - 8 years), check the technical condition and setting the protection settings on the overcurrent releases of the automatic switches ABM and AV power input of the DC boards.
During the maintenance of the AC switchboard equipment, inspection, lubrication, regulation, checking the performance of circuit breakers and their releases, repairing fuses, checking primary current protection from an external source, with a mandatory revision of contact connections and checking the cross-section of jumpers and busbars is carried out. In case of detection of a decrease in the cross-section caused by corrosion-oxidative processes, they are replaced to avoid burnout during a jogging load.
Work on the AC switchboard should be carried out according to specially developed programs (flow charts), inspections according to the work schedule of operating personnel, together with an inspection of substation equipment.
During acceptance tests after overhaul and preventive recovery, the following scope of work is performed:
Insulation resistance values should be not less than those given in table 1.
Table # 1. Permissible values of insulation resistance of devices, secondary circuits and electrical wiring.
|
Test item |
Rated voltage of megohmmeter, kV |
The smallest admissible value of insulation resistance, MOhm |
|
Secondary circuits with installed microelectronic elements, which are designed for rated voltage, V: |
||
|
Power wiring * |
||
|
Secondary circuits of switchgear ** boards and conductors |
* The insulation resistance with the fuse-links removed is measured on the section between the fuse of a wire and the ground, as well as between the wires. When measuring the insulation resistance, it is necessary to turn off electrical receivers, devices, etc.
** The insulation resistance of the secondary circuits of each section of the switchgear is measured.
2. Test with increased voltage of industrial frequency. The test voltage value for isolation with respect to earth and secondary circuits with a fully assembled circuit (together with relays, contactors, drive coils, etc.) for voltages above 60 V is 1000 V.
The duration of the test is 1 minute.
If the tested circuits contain elements designed for a lower test voltage, they must be disconnected and tested separately or shunted.
3. Checking the performance of releases (thermal, electromagnetic, semiconductor) is carried out in accordance with the recommendations of the manufacturer at the operating settings.
4. Checking the functionality of circuit breakers, contactors and magnetic starters. Circuit breakers, contactors and magnetic starters must be able to open, trip and be held securely in the closed position at the factory-specified holding voltage.
The response voltage value and the number of operations are shown in Table 2.
Table 2. Operating voltage values and number of operations during testing of circuit breakers, contactors and magnetic starters.
* Depends on the manufacturer's requirements for the specific type of circuit breaker.
** If, according to the operating conditions, the auxiliary current source cannot be increased to 1.1Unom., Testing at maximum voltage is allowed.
5. Checking the switchgear phasing and connections. When phasing the switchgear and connections, there must be a phase coincidence.
6. Testing with increased voltage of industrial frequency during preventive restoration of devices. During preventive restoration of devices, secondary circuits and electrical wiring for voltages up to 1 kV instead of the test according to clause 2. of this section, it is allowed to carry out tests with a rectified voltage of 2.5 kV using a megohmmeter or a special installation.
During the current operation (6-8 years), the insulation of the boards is cleaned, the bolted connections are tightened, the contact connections of the knife switches, fuses (if necessary, the circuit breakers, contactors, starters) are cleaned and lubricated, the fuses are calibrated. The insulation resistance is measured in accordance with clause 1. of this section.
4. Security measures.
Work on AC switchboards (bus sections, sectional disconnector, connections through which voltage can be applied to AC buses) must be carried out according to a permit. When working on AC boards from all sides of the live parts on which the work will be carried out, it is necessary to remove the voltage by disconnecting the switching devices with a manual drive, and if there are fuses in the circuit, removing them. In the absence of fuses in the circuit, to prevent erroneous switching on of switching devices, the following measures should be taken: locking the cabinet door handles, closing buttons, installing insulating pads between the contacts of the switching devices, etc. When the voltage is removed by the remote-controlled switching device, it is then necessary to disconnect the wire supplying the closing coil if there are no fuses in the circuit. If the design of the equipment and the nature of the work allow, then the above measures must be replaced by unbundling or disconnecting the cable, wires from the switching device or from the equipment on which the work is to be carried out. An employee with a group of 3 from the production workers under the supervision of a duty officer or an employee from the operational production workers can unbind or disconnect the cable, wires during the preparation of the workplace. It is necessary to remove the voltage from the live parts closest to the workplace, which are accessible to touch, or they should be protected. The disconnected position of switching devices up to 1000 V with contacts inaccessible for inspection (non-withdrawable circuit breakers, packet switches, closed circuit breakers, etc.) is determined by checking the absence of voltage at their terminals or on outgoing buses, wires or terminals of equipment switched on by these switching devices ... It is necessary to remove and install the fuses with the voltage removed. Under voltage, but without load, it is allowed to remove and install fuses on connections, in the circuit of which there are no switching devices that allow you to remove voltage. Under load, it is allowed to change the fuses in the secondary circuits, lighting networks and VT fuses. When removing and installing fuses while energized, you must use insulating pliers or dielectric gloves, work should be done with protective goggles (masks).
On AC shields it is necessary: to fence off live parts located near the workplace, which are energized, to which accidental contact is possible; work in dielectric bots or while standing on an insulating stand or rubber dielectric mat; use a tool with insulating handles, in the absence of such a tool, use dielectric gloves.
Thousands of people around the world are involved in repairs every day. When performing it, everyone begins to think about the subtleties that accompany the repair: in what colors choose wallpaper, how to choose curtains in the color of the wallpaper, arrange furniture correctly to obtain a uniform style of the room. But rarely does anyone think about the most important thing, and this is the main thing to replace the electrical wiring in the apartment. After all, if something happens to the old wiring, then the apartment will lose all its attractiveness and become completely unsuitable for life.
Any electrician knows how to replace the wiring in an apartment, but any ordinary citizen can do this, however, when performing this type of work, he should choose high-quality materials in order to get a safe electrical network in room.
The first action to be taken is plan future wiring... At this stage, you need to determine exactly where the wires will be laid. Also at this stage, you can make any adjustments to the existing network, which will make it possible to arrange the lamps and in the most comfortable way in accordance with the needs of the owners.
Narrow-branch devices of the knitted sub-industry and their maintenance
To determine the extensibility of hosiery, a device is used, the diagram of which is shown in Fig. 1.
The design of the device is based on the principle of automatic balancing of the rocker arm by elastic forces of the test product acting at a constant speed.
The weight rocker is an equal-armed round steel rod 6 with an axis of rotation 7. On its right end, legs or a sliding form of the track 9 are attached to its right end using a bayonet lock, on which the product is put on. A suspension for loads 4 is pivotally attached to the left shoulder, and its end ends with an arrow 5, showing the equilibrium state of the rocker arm. Before testing the product, the rocker arm is brought into equilibrium with a movable weight 8.
Rice. 1. Diagram of a device for measuring the extensibility of hosiery: 1 — guide, 2 — left ruler, 3 — slider, 4 — suspension for loads; 5, 10 - arrows, 6 - rod, 7 - axis of rotation, 8 - weight, 9 - track shape, 11 - tension arm,
12 - carriage, 13 - lead screw, 14 - right ruler; 15, 16 - helical gears, 17 - worm gear, 18 - coupling, 19 - electric motor
In pneumatic actuators, the adjustment force is generated by the action of compressed air on the diaphragm, or piston. Accordingly, the mechanisms are diaphragm, piston and bellows. They are designed to position and move the control valve gate in accordance with a pneumatic command signal. The full working stroke of the output element of the mechanisms is carried out when the command signal changes from 0.02 MPa (0.2 kg / cm 2) to 0.1 MPa (1 kg / cm 2). The limiting pressure of compressed air in the working cavity is 0.25 MPa (2.5 kg / cm 2).
In linear-thrust diaphragm mechanisms, the rod reciprocates. Depending on the direction of movement of the output element, they are subdivided into mechanisms of direct action (with an increase in membrane pressure) and reverse action.
Rice. 1. Membrane design actuator direct action: 1, 3 - covers, 2 - membrane, 4 - support disc, 5 - bracket, 6 - spring, 7 - stem, 8 - support ring, 9 - adjusting nut, 10 - connecting nut
The diaphragm pneumatic chamber of the direct action mechanism (Fig. 1) consists of covers 3 and 1 and membrane 2. Cover 3 and membrane 2 form a sealed working cavity, cover 1 is attached to the bracket 5. The movable part includes support disk 4, to which the membrane is attached 2, a rod 7 with a connecting nut 10 and a spring 6. The spring at one end abuts against the support disk 4, and the other through the support ring 8 into the adjusting nut 9, which serves to change the initial tension of the spring and the direction of movement of the rod.
Today there are several types of lamps for. Each has its own pros and cons. Consider the types of lamps that are most often used for lighting in a residential building or apartment.
The first type of lamps - incandescent lamp... This is the cheapest type of lamp. The advantages of such lamps include its cost, simplicity of the device. The light from these lamps is the best for the eyes. The disadvantages of such lamps include a short service life and a large amount of electricity consumed.
The next type of lamps is energy-saving lamps... Such lamps can be found for absolutely any type of base. They are an elongated tube in which there is a special gas. It is the gas that creates the visible glow. In modern energy-saving lamps, the tube can have a wide variety of shapes. Advantages of such lamps: low power consumption compared to incandescent lamps, daylight, large selection plinths. The disadvantages of such lamps include the complexity of the design and flicker. The flickering is usually subtle, but the eyes will get tired of the light.
Cable assembly- a kind of mounting assembly. The cable assembly consists of several local ones, terminated on both sides in an electrical installation shop and tied into a bundle. The installation of the cable route is carried out by laying the cable assembly into the cable route fastening device (Fig. 1).
Ship cable route- an electrical line mounted on a ship from cables (cable bundles), cable routing fixing devices, sealing devices, etc. (Fig. 2).
On the ship, the cable route is located in hard-to-reach places(along the sides, ceiling and bulkheads); they have up to six turns in three planes (Fig. 3). On large ships, the maximum cable length reaches 300 m, and the maximum cross-sectional area of the cable route is 780 cm 2. On individual ships with a total cable length of over 400 km, cable corridors are provided for placing the cable route.
Cable routes and cables passing through them are subdivided into local and trunk routes, depending on the absence (presence) of sealing devices.
Trunk cable routes are subdivided into routes with end boxes and pass-through boxes, depending on the type of use of the cable box. It makes sense for the choice of technological equipment and cable routing technology.
In the field of development and production of instrumentation and automation devices, the American company Fluke Corporation occupies one of the leading positions in the world. It was founded in 1948 and since that time has been constantly developing and improving technologies in the field of diagnostics, testing, analysis.
Use a level gauge to determine the level different types liquids in open and closed storages, vessels. It is used to measure the level of a substance or the distance to it.
To measure the liquid level, sensors are used that differ in type: radar, microwave (or waveguide), radiation, electrical (or capacitive), mechanical, hydrostatic, acoustic.
One of the main tasks of operating switchgears is to maintain the necessary reserves in terms of dynamic, thermal stability, throughput, voltage level in the device as a whole and in its individual elements. These tasks can be achieved with proper maintenance of the switchgear. During maintenance, switchgears are inspected, and during routine repairs, noticed faults that require disassembly of the equipment are eliminated. Routine repairs are carried out at the installation site of the equipment, while the defective parts are replaced, after their replacement, the switchgears are adjusted and tested.
Inspection frequency of switchgear... The frequency of inspection is set depending on the type of device, its purpose and the form of service. The approximate dates of inspections are as follows:
in switchgears serviced by shift personnel on duty at the substation itself or at home - every day. In unfavorable weather (wet snow, fog, heavy and prolonged rain, ice, etc.), as well as after short circuits and when a ground fault signal appears in the network, additional inspections are carried out. It is recommended to inspect the device once a week in the dark to detect possible corona discharges in places of insulation damage and heating of live parts;
in switchgears of substations with a voltage of 35 kV and above, which do not have permanent personnel on duty, the inspection schedule is made depending on the type of device (closed or open) and on the purpose of the substation. In this case, the inspections are performed by the head of the substation group or the foreman at least once a month;
transformer substations and switchgears of electrical networks with a voltage of 10 kV and below, which do not have
duty personnel, examined at least once every six months;
extraordinary inspections at facilities without permanent personnel on duty are carried out within the time frame established by local instructions, taking into account the short-circuit power and the state of the equipment. In all cases, regardless of the value of the cut-off short-circuit power, inspect the circuit breaker after a cycle of unsuccessful automatic reclosing (AR) and tripping due to a short circuit.
All malfunctions noticed during inspections of switchgears are recorded in the operating log. Faults that interfere with normal operation must be eliminated as soon as possible. The serviceability of the switchgear backup elements (transformers, switches, busbars, etc.) should be regularly checked, including energized, within the timeframes set by local regulations. The standby equipment must be ready to turn on at any time without any preliminary preparation. The frequency of cleaning the switchgear from dust and dirt depends on local conditions. It is installed by the chief engineer of the enterprise.
Maintenance of switches... External inspections of oil switches without shutdown are carried out taking into account local conditions, but at least once every six months, together with inspections of the switchgear. During inspections, they check: the condition of the insulators, fasteners and busbar contacts, the oil level and the condition of oil indicators; no oil leakage from lattice contacts of small-volume switches or through gaskets of tank switches. The oil level at the switches largely determines the reliability of their operation. It should not go beyond the oil gauge at ambient temperatures from -40 "to +40 ° C. An increased oil level at the poles and, accordingly, a reduced air cushion volume above the oil lead to excessive pressure in the tank when the arc is extinguished, which can cause destruction of the switch.
Reducing the volume of oil also destroys the switch. It is especially dangerous in small-volume switches VMG-10, VMP-10. If the leak is significant and there is no oil in the oil gauge glass, then the switch is repaired and the oil in it is replaced. In this case, the load current is interrupted by another switch or the load on this connection is reduced to zero. Abnormal heating of the arc-extinguishing contacts of small-volume switches causes darkening and a rise in the oil level in the oil sight glass, as well as a characteristic odor. If the temperature of the switch reservoir exceeds 70 ° C, the switch should be repaired.
In areas with a minimum temperature below 20 ° C, circuit breakers are equipped with automatic devices for heating oil in tanks. It is recommended to check the circuit breaker drives at least once every three (six) months. In the presence of automatic reclosing, it is advisable to test for disconnection from relay protection with switching off from automatic reclosure. If the circuit breaker fails to operate, it must be repaired.
During external inspection of air switches, attention is paid to its general condition, to the integrity of the damping chamber insulators, separators, shunt resistances and capacitive voltage dividers of the support columns and insulating braces, as well as to the absence of contamination of the surface of the insulators. Using the pressure gauges installed in the switch cabinet, check the air pressure in the tanks of the switch and its flow to ventilation (for switches operating with automatic reclosing, the pressure should be in the range of 1.9 ... 2.1 MPa and for switches without automatic reclosing - 1, 6 ... 2.1 MPa). An interlock is provided in the circuit breaker control circuit, which prevents the circuit breaker from operating when the air pressure drops below normal.
During the inspection, they also control the serviceability and correctness of the readings of the devices signaling the on or off position of the switch. Pay attention to whether the dampers of the exhaust hoods of the extinguishing chambers are securely closed. Visually check the integrity of the rubber gaskets in the joints of the extinguishing chamber insulators, separators and their support columns. They control the degree of heating of the contact connections of buses and hardware connections. When using air switches 1-2 times a month, accumulating condensate is removed from the tanks. During the rainy season, the air supply for ventilation increases, when the ambient temperature drops below minus 5 ° C, electric heating is switched on in the control cabinets and in the distribution cabinets. At least twice a year, the operability of the circuit breaker is checked by means of tripping and closing tests. To prevent damage to the switches, the bolts of all sealing joints are checked and tightened 2 times a year (in spring and autumn).
Service of complete switchgears... Operation of complete switchgears (KRU) has its own characteristics due to the limited overall dimensions of the cells. To protect personnel from accidental contact with live parts that are energized, the switchgear is provided with an interlock. In stationary switchgear, mesh doors are blocked, which are opened only after the circuit breaker and disconnectors are disconnected. The draw-out switchgear has automatic shutters that block access to the compartment of fixed disconnecting contacts when the trolley is pumped out. In addition, there is an operational blocking, which protects personnel when performing erroneous operations. For example, rolling out of the trolley into the test position is permitted by interlocking only after the circuit breaker has been turned off, and rolling-in of the trolley into the working position - with the disconnected position of the circuit breaker and earthing knives. The equipment is monitored through inspection windows and mesh fences or inspection hatches covered with a protective mesh.
Inspections of the switchgear without disconnecting them are carried out according to the schedule, but at least once a month. During inspections, they check the operation of lighting and heating networks and switchgear cabinets; condition of switches, drives, disconnectors, primary disconnecting contacts, interlocking mechanisms; contamination and absence of visible damage to insulators; the state of the secondary switching circuits; action of control buttons of switches. Systematically, depending on local conditions, they clean the insulation from dust and pollution, especially in outdoor switchgear (KRUN). When inspecting complete switchgears KRU and KRUN, attention is paid to the condition of the seals at the joints of the elements of metal structures; serviceability of equipment connection to the ground loop; availability of security and fire extinguishing equipment; operation and serviceability of heating devices for KRUN cabinets; presence, sufficiency and normal color of oil in the switches; condition of field connections; heating of live parts and devices; lack of extraneous noise and odors; serviceability of signaling, lighting and ventilation. Simultaneously with the inspection, the correct position of the switching devices is checked. The equipment built into the KRU and KRUN is inspected in accordance with the operating instructions.
When operating the switchgear, it is forbidden to unscrew the removable parts of the cabinet, lift and open automatic shutters in the presence of voltage in those places to which they are closed. In draw-out type switchgear cabinets for earthing outgoing lines using disconnectors built into the switchgear, you need to do the following: turn off the switch, roll out the trolley, check the absence of voltage on the lower disconnecting contacts, turn on the earthing switch, put the trolley in the test position.
The fuses in the auxiliary transformer cabinet can only be changed when the load is removed. When carrying out work inside the compartment of the roll-out cart, it is necessary to hang warning posters on the automatic shutter: “Do not turn on! People work ”,“ High voltage! Life threatening!" Only trained operating personnel can roll out the trolley with the switch and set it to the working position.
It is allowed to roll the cart into the working position only with the disconnected position of the earthing switch.
Disconnector service... When regulating the mechanical part of three-pole disconnectors, check the simultaneity of turning on the knives. When adjusting the moment of contact and compression of the movable knives, the length of the rod or the stroke of the limiters and thrust washers is changed, or the insulator on the base or the jaws on the insulator slightly move. When fully turned on, the knife should not reach the stop of the contact pad by 3-5 mm. The smallest pulling force of one knife from a fixed contact should be 200 N for disconnectors for rated currents of 400 ... 600 A and 400 N for disconnectors for rated currents of 1000 ... 2000 A. direct current, which must be within the following limits: for disconnectors RLND (35 ... 220 kV) for a rated current of 600 A - 220 μOhm; for other types of disconnectors for all voltages with a rated current of 600 A - 175 μOhm, 100 A - 120 μOhm; 1500-2000 A - 50 μOhm.
The contact surfaces of the disconnectors during operation are lubricated with neutral petroleum jelly with an admixture of graphite. The rubbing parts of the drive are coated with an anti-freeze grease. The condition of the isolators of the disconnectors is assessed by the insulation resistance, the voltage distribution on the steel elements of the pin insulators or by the results of testing the insulator with increased power frequency voltage.
The auxiliary contacts of the drive, intended for signaling and blocking the position of the disconnector, must be installed so that the signal about disconnecting the disconnector begins to act after the knife has passed 75% of the full stroke, and the signal about switching on - not earlier than the moment the knife touches the fixed contacts.
Service of short-circuits and separators... Short-circuits are devices designed to artificially create a short circuit in cases where the current in case of damage in the transformer may be insufficient for the relay protection to operate. The short-circuiter is turned on by an automatic drive when the relay protection is triggered, and it is turned off manually.
When disconnecting power transformers without load, as well as automatically disconnecting damaged transformers, separators are used. The separator is switched off automatically or manually, switched on - only manually using a removable handle. At 35 ... 11O kV connections with separators and disconnectors installed in series, the magnetizing current of transformers and capacitive currents of the line should be disconnected by separators. With 35 kV separators, it is possible to disconnect the earth fault current up to 5 A.
On average, for 10 km of 35 kV overhead lines, the charging current is 0.6 A and the earth fault current is 1 A.
Short-circuits and separators are inspected at least 2 times a year, as well as after emergency shutdowns. During inspections, special attention is paid to the condition of the insulators, contacts, grounding wire passed through the current transformer window. If traces of burning are found, the contacts are cleaned or replaced. The duration of the movement of the moving parts of the short-circuiter for voltages of 35 and 110 kV from the impulse to the closure of the contacts should be no more than 0.4 s, and the time of the separator from the impulse to the opening of the contacts, respectively, 0.5 and 0.7 s.
During the operation of short-circuits and separators, special attention should be paid to the most unreliable assemblies: open or insufficiently protected springs from possible contamination and icing, contact systems and pivot joints, as well as unprotected bearings protruding from the rear side.
When setting up the short-circuit and the separator, pay attention to the reliable operation of the separator latching relay (BRO), which is designed for currents of 500 ... 800 A. Therefore, with short-circuit currents less than 500 A, the ground bus should be replaced with a wire and passed through the current transformer several times ... If this is not done, the BRO relay will tighten the armature indistinctly and thereby release the locking mechanism of the separator drive until the short-circuit current is cut off. Premature disconnection of separators is one of the reasons for their destruction.
Current repair of disconnecting devices, as well as checking their operation (testing) is carried out as necessary within the time frame established by the chief engineer of the enterprises. The scope of work on current repair includes: visual inspection, cleaning, lubrication of rubbing parts and measurement of the resistance of the contacts to direct current. Unscheduled repairs are performed in the event of external defects, contact heating or unsatisfactory insulation conditions. The adjustment of the short-circuiter and the separator consists in checking the operation of the drive for switching on and off, checking the position of the knives and the factory of the opening spring of the drive with the blocking relay BRO, adjusting the stroke of the cores of the electromagnets and relays.
Monitoring the state of live parts and contact connections... The condition of current-carrying parts and contact connections of buses and switchgear devices is checked during inspections. The heating of detachable connections in closed switchgears is monitored using electrothermometers or thermal candles and thermal indicators. The operation of the electrothermometer is based on the principle of measuring the temperature using a thermistor glued to the outer surface of the sensor head and covered with copper foil. The heating temperature of the contact joints is determined using a set of thermal candles with different melting points. As thermal indicators, reversible films of repeated action are used, which change their color upon prolonged heating. The thermal indicator must withstand, without collapsing, at least 100 color changes during prolonged heating to a temperature of 110 ° C.
Maintenance of grounding devices... During operation, inspections, periodic checks and tests of grounding devices are carried out in accordance with the recommendations of the PPR.
In the area of grounding devices subject to intense corrosion, a more frequent measurement frequency is set. Unscheduled measurements of the resistance of grounding devices are carried out after their reconstruction or overhaul. The resistances of the grounding devices are measured with special devices MS-08, M-416, F4103 or by the ammeter-voltmeter method. Schematic diagrams for switching on the MC-08, M-416, F4103 devices are shown on the instrument covers or in the instructions. As auxiliary grounding devices, metal rods with a diameter of 12 ... 16 mm are used, which are driven into the ground to a depth of 0.5 m at a distance specified in the instructions.
SCHEMETECHNOLOGICALREPAIR PROCESSTRANSFORMER
The most vulnerable and often damaged part of the transformer is its HV winding and, less often, LV. Damage most often occurs due to a decrease in the dielectric strength of the insulation in any part of the winding.
In transformers, bushings, switches, cover and other parts can also be damaged. The approximate ratio of damage to individual parts of the transformer is as follows:
windings and conductive parts - 53%;
switches -12%;
all other parts taken together - 17%.
Investigations into the causes of transformer failures have shown that accidents usually occur due to poor maintenance and poor repair quality.
A transformer with damaged windings or other parts must be immediately taken out of service and repaired. The company draws up an acceptance certificate with the attachment of a list of defects and places an order. The documents record the order number, passport data, customer requirements, the results of external inspection, verification tests and measurements. All defects discovered in the further process of disassembling the transformer are also entered into the list of defects. Based on these data, the scope of repair work is determined.
The most common in the electrical repair shops of most enterprises, the technological scheme for the repair of three-phase oil-cooled transformers is shown in Figure 16.1.
In accordance with this scheme, the damaged transformer, which is in the warehouse of faulty transformers, enters the defect and preparatory department, which consists of three sections - disassembly and washing, diagnostics of windings and the mechanical part of the transformer. At the dismantling site, the transformer is cleaned, the oil is drained from its expander, tank and oil-filled bushings, and then, after making sure from the records in the accompanying documents and from preliminary tests that the transformer is faulty, proceed to its disassembly.
Damage to the external parts of the transformer (conservator, tank, fittings, external part of the bushings, breakdown fuse) can be detected by thorough examinations, and internal parts by various tests. However, the test results do not always allow us to accurately establish the actual nature of the damage, since any deviation from the norm identified as a result of the tests (for example, increased no-load current) can be caused by various reasons, including a turn circuit in the winding, the presence of a closed current loop through tie bolts and pressing parts, incorrect connection of parallel windings, etc. Therefore, in the diagnostic process, as a rule, the transformer is disassembled and, if necessary, the active part is raised, which allows not only to accurately establish the causes, nature and extent of damage, but also to determine the required for repair of the transformer materials, tools and fixtures, and time.
DISASSEMBLYANDDEFINITIONTROUBLESHOOTING
The sequence of disassembly operations in each case depends on the design of the transformer to be repaired. Modern transformers of domestic production, differing in power and design, and transformers of the previous years, as well as those produced in the past and currently supplied by foreign companies, are being repaired, therefore, we recommend any unified technological sequence for disassembling and repairing all incoming transformers impossible.
Before disassembly, check the completeness of the transformer received for repair (all assembly units and parts required for this design must be available), as well as the connection of its external parts, the integrity of the welds and joints, the absence of oil leakage from the flange connections of the fittings with the tank.
The first stage of disassembly... Disassembly begins with dismantling the gas relay, thermometer, expander, safety pipe and other devices and parts located on the transformer cover.
Having removed the relay, the safety pipe and the expander, the disassembly is continued, proceeding to the dismantling of the transformer cover, which is carried out with the observance of precautions to exclude damage to the porcelain parts of the HV and LV winding bushings. The bolts removed from the entire perimeter of the cover, together with the washers put on them and the nuts screwed onto their threads, are washed, covered with anti-corrosion grease and stored in boxes for reuse when assembling the transformer.
The cover, freed from the bolts, is strapped over the lifting eyes, screwed onto the threaded ends of the lifting pins protruding from the cover, fixed on the yoke beams of the upper yoke of the magnetic circuit. Transformers with power up to 4UU kVA usually have two lifting eyes, with higher power - four. To lift the active part, special devices and slings are used, designed for the mass of the load being lifted and having passed the necessary tests. When dismantling radiators and other large parts of an outdoor transformer, a truck crane is used as a lifting mechanism.
When lifting the active part of transformers with bushings located on the walls of the tanks, first disconnect the taps and dismantle the bushings, and then raise the active part of the transformer. The active part, raised from the tank, is installed on a solid platform made of curved boards or on wooden beams so as to ensure its stable vertical position and the possibility of inspection, inspection and repair.
Continuing disassembly, disconnect the taps from the inputs and the switch and check the condition of their insulation, reinforcement seams of the inputs and the contact system of the switch (all noticed faults are recorded). Next, the eyelets are unscrewed from the vertical pins, the cover is removed, taken to the side and laid so that the bars protruding under the cover are not damaged, the bushings are protected from mechanical damage by covering them with rigid cardboard cylinders or wrapping them with clean burlap.
Second stage of disassembly, the most difficult and time-consuming, is the dismantling of the windings, the main operations of which are performed in the following sequence: remove the vertical studs, unscrew the nuts of the tie bolts and remove the yoke beams of the magnetic circuit, loosen the upper yoke of the magnetic circuit, tying and arranging the plate packs in the order in which they will be more convenient lay when blending the upper yoke. Next, the connections of the windings are disassembled, the taps are removed, the wooden and cardboard parts of the wedging of the HV and LV windings are removed and the windings are manually removed from the rods of the winding of the transformer with a capacity of up to 63 kV A) or using a lifting mechanism (winding of transformers with a capacity of 100 kV A and above) - first HV and then NN.
After disassembling the transformer, inspect its outer part. At the same time, the cleanliness of the windings is checked, paying special attention to the channels between the windings and the magnetic circuit. The places of weakening of the turns are revealed by touch. In these places, as a rule, the winding insulation is damaged, charred as a result of turn-to-turn short circuits, invisible from the outside. Inspect by external inspection the condition of the insulation, the absence of deformations and displacement of the windings or its turns, the presence of insulating gaskets, wedges, spacers.
Safe switching operations in switchgear can be guaranteed if personnel strictly adhere to the following operating procedures:
Disconnection must be done so that there are gaps between the disconnected and live parts that are under voltage, visible from all sides.
According to intersectoral labor safety rules, the following distances from people, the tools, devices and temporary fences they use to electrical equipment are determined, depending on the voltage values of the installations (Table 8.2), as well as from mechanisms, hoisting machines, slings and loads (Table 8.3).
Particular attention must be paid to the possibility of reverse transformation of low voltage through transformers. To prevent this from happening, power and measuring transformers related to the equipment to be switched off are also disconnected from the low voltage side. In order to prevent spontaneous or erroneous switching on of switches and disconnect
8.2. Distances from people, tools, devices and temporary fences they use to live parts of electrical equipment at different voltages
8.3. Distances from mechanisms, hoisting machines, slings, loads to live parts of electrical equipment at various voltages 
In the power circuits of the remote drives of the disconnected disconnectors, remove the fuses on both poles. All disconnector drives accessible to unauthorized persons are padlocked.
On all control keys and drives of switches and disconnectors, with the help of which voltage can be applied to the place of work, the worker performing the disconnection hangs up posters: "Do not turn on - people are working!" When working on the line, posters are posted on the drives of the linear disconnectors: "Do not turn on - work on the line!"
On the diagram of the dispatcher in charge of the shutdown, they hang out as many posters as the number of teams working.
Temporary fencing can be special solid or lattice wooden screens, products made of micanite, rubber and other insulating materials, which are in a dry state and well strengthened.
The need to install fences, their type, method of installation are determined depending on local conditions and the nature of the work. Temporary fences are hung with posters: "Stop - High Voltage!"
After installing the warning signs and temporary barriers, personnel prepare the portable grounding kit, connect it to the grounding wiring, and then check the parts of the installation that are to be operated for no voltage.
To check for the absence of voltage, a voltage indicator is used. Immediately before checking, make sure that the pointer is in good working order by bringing it closer to live parts located nearby and knowingly energized. These checks are carried out with dielectric gloves. When checking for the absence of voltage in open switchgears with voltages of 35 and 110 kV, a spark gap is attached to the working part of the indicator screwed onto the rod. If there is tension, then light and sound signals appear (characteristic crackling). This check is done only in dry weather. After checking the installation for the absence of voltage, ground and short-circuit the current-carrying parts of all phases on which work will be carried out or from which voltage can be applied to the part of the installation disconnected for operation.
Disconnected equipment is grounded immediately after checking for absence of voltage. In this case, it is not allowed to impose grounding without first connecting it to the grounding device. The portable grounding clamps are applied using a rod made of insulating material on the grounded live parts of all phases, then the clamps are securely connected with the same rod or directly with your hands in dielectric gloves. After laying the grounding, a poster is posted at the work site: "Work here!" Temporary portable groundings are made of bare, flexible stranded wires with an area cross section not less than 25 mm 2, tested for thermal stability.
When removing the grounding, it is first removed from the live parts, and then disconnected from the grounding circuit. The work order is closed after inspecting the equipment and the place where the work was carried out. Only after the closure of the work order, the equipment is turned on for work, having previously performed the following operations:
If several brigades were working on a disabled installation, then it can be turned on only after all the orders have been closed.
The serviceability of the insulation of the equipment switched on after repair is checked with a megohmmeter. This makes it possible to identify insulation defects that are difficult to detect by inspection.
If an earth fault is detected, then before disconnecting the damaged section in closed switchgears, it is impossible to approach the place of damage at a distance of less than 5 m, and at open substations - at a distance of 10 m. provide first aid to the injured. In these cases, personnel must be very careful and use all necessary protective equipment.
In case of accidents with people, the voltage can be relieved from the corresponding part of the installation without the permission of the superior operating personnel.
