TO technical means protection include fencing, safety, braking and blocking devices, alarm systems, remote and automatic control or performing operations, emergency devices.
Hazardous area fencing protect operating personnel from injury from various gears, as well as moving and rotating parts and mechanisms from electromagnetic and thermal radiation arising during equipment operation, from flying particles of the material being processed, gases, dust, aerosols, etc.
Safety devices eliminate the possibility of injury service personnel, accidents and equipment breakdowns, and also protect workers from entering the danger zone during maintenance and operation.
Means of protection installed on agricultural machinery must meet a number of requirements. The basic requirements for hazardous area barriers are as follows:
– the design of the fencing of hazardous areas does not impede normal operation and maintenance;
– is not a source of noise;
– by type of design, the design corresponds to the fenced hazardous area;
– provides visibility of the working area and, if necessary, danger zone, has a color that creates a normal perception by service personnel;
– where necessary, the fencing structure is interlocked with the most dangerous units and mechanisms being protected;
– meets the requirements of technical aesthetics;
– transmission mechanisms are separated by continuous protective fences designed for strength;
– the protective guard of the cardan transmission does not rotate with the shaft;
– fences are organically connected with the design of the equipment, providing reliable shelter of the hazardous area and ease of maintenance;
– equipment with a hydraulic drive operating under pressure is covered or equipped with reliable screens that exclude the possibility of liquid being released into workplaces if they are damaged;
– fences of places to be inspected, easily removable and opening, have handles, brackets or other devices for holding them safely when opening or removing them;
– fences that open upward are equipped with devices for securely fixing them in the open state;
– removable fences have fastenings that do not require the use of keys and screwdrivers.
Safety devices to protect workers from entering a hazardous area are carried out in the form of mechanical or electrical interlocks, photoelectric or electronic protection, two-handed activation, alarms, etc. Equipment for which there is a risk of accidents, overloads, breakdowns is equipped with such safety devices as friction couplings, devices with automatic alarm, automatic shutdown or other devices. Protective equipment also addresses a number of electrical safety issues.
Fencing. According to their design, fencing devices are divided into removable, stationary and portable.
Removable barriers limit access mainly to external transmissions (belt, chain and gear), and are made in the form of covers, casings, covers. They are made mesh, lattice or solid.
Stationary fences are made in the form of cases, covers, boxes and are often elements of external parts of machines or frames. They are made solid or louvered.
Portable fences, being temporary elements of the workplace, serve to prevent touching hot surfaces, live parts and structural elements that can cause mechanical injuries. They are made in the form of portable shields and are used for repair and adjustment work. An example of such devices could be fencing pits, trenches, an electric welder's workplace, wells in the production of excavation, installation or repair work and etc.
Safety devices turn off the equipment when the controlled parameter (pressure, temperature, force, displacement, etc.) goes beyond the permissible limits or reduces the value of the parameter to the permissible level. Safety devices are divided into 4 groups: for protection against excess pressure and temperature, against mechanical overloads, against moving parts of the machine exceeding established limits, and against electric shock.
To protect against overpressure, safety devices are made in the form of valves and membranes.
To protect against mechanical overloads and prevent related accidents, couplings, load limiters, speed controllers, shear pins and studs are used.
To protect against moving parts going beyond the established limits and prevent associated machine breakdowns, limit switches (travel limiters), stops, grips and stops are used.
To protect against electric shock, fuses and circuit breakers are used. The ingress of electric current onto live parts of equipment that is not energized under normal conditions is prevented by the use of fuses, which, when the current reaches a dangerous value, melt and interrupt the electrical circuit.
Braking devices serve to prevent spontaneous lowering of a load, quickly stopping moving machines and parts of equipment, holding machines on descents or ascents, etc. The degree of danger of injury from moving machines and equipment depends not only on their speed, but also on the time of operation of the braking devices. Braking efficiency is assessed by the length of the braking distance.
Locking devices safety devices are designed to prevent injuries by stopping the operation of equipment or machinery when the hazardous area is not fenced off. The need for interlocking devices is dictated by the fact that the use of barriers, safety devices or braking does not always ensure safety.
Devices that block the possibility of starting movement of tractors and other mobile machines equipped with a cab and pneumatic braking systems do not allow moving off when open doors cabins and insufficient pressure in the braking system. Such a device is included in the pneumatic system of the machine.
Protective devices are special additions to the main equipment and serve to ensure the safety of its operation and the protection of operating personnel. The need for protective devices is associated with the emergence of so-called dangerous zones, i.e. spaces in which situations constantly occur or periodically arise that are dangerous to the life and health of service personnel. Hazardous zones arise during the operation of machines, machines and devices that have moving, rotating, pushing, cutting parts and parts, as well as during the operation of lifting
but transport mechanisms and execution repair and installation work. In equipment design and engineering technological process Dangerous areas must be identified and measures must be taken to eliminate them or use protective devices to prevent a person from entering hazardous areas.
Protective devices against mechanical injury include safety brakes, fencing devices, automatic control and alarm systems, safety signs, and remote control systems.
Remote control systems and automatic alarms for dangerous concentrations of vapors, gases, and dusts are used in explosive industries and industries with the possibility of releasing toxic substances into the air of the working area.
Safety protective devices are intended for automatic shutdown units and machines when any parameter deviates (increases in pressure, temperature, operating speeds, current, torque, etc.), characterizing the operating mode of the equipment, beyond acceptable limits. This eliminates the possibility of explosions, breakdowns, and fires. In accordance with GOST 12.4.125-83, safety protective devices can be interlocking or restrictive according to the nature of their action.
According to the principle of operation, locking devices are divided into mechanical, electrical, electronic, electromagnetic, pneumatic, hydraulic, optical, magnetic and combined.
Limiting devices for design are divided into couplings, pins, valves, keys, membranes, springs, bellows and washers.
Locking devices prevent a person from entering the dangerous zone or are removed while he is in this zone dangerous factor. Most often, these types of protection are used in machines and units that do not have guards, or if work can be carried out with the guard removed or open.
Mechanical interlocking is a system that provides communication between the guard and the braking (starting) device. With the guard removed, it is impossible to release the brakes and, therefore, to put it into operation.
Electrical interlocking is used in electrical installations with voltages of 500 V and above, as well as in various types technological equipment with electric drive. It ensures that the equipment is turned on only if there is a fence.
Electromagnetic interlocking is used to prevent a person from entering a danger zone. If this happens, the high-frequency generator supplies a current pulse to the electromagnetic amplifier and polarized relay.
The electromagnetic relay contacts de-energize the magnetic starter circuit, which provides electromagnetic braking of the drive in tenths of a second. Magnetic blocking, which uses a constant magnetic field, and optical blocking work similarly. In the latter case, rays from the light source are directed through the danger zone to a photocell, which converts the light into electricity, which, having passed through the amplifier and control relay, closes the starting electromagnet circuit. When a person enters the danger zone, light stops entering the photocell, electrical circuit opens and the machine drive is switched off. Optical blocking is used to protect hazardous areas on presses, guillotine shears, and stamping machines.
Pneumatic and hydraulic locks are used in units where working fluids are under increased pressure: turbines, compressors, blowers, etc. If the permissible pressure value is exceeded, the pressure switch sends a pulse to the electromagnet, which closes the shut-off device (quick-acting valve) on the working substance supply line and at the same time stops the unit drive.
Examples of limiting devices are elements of mechanisms and machines designed to be destroyed (or triggered) under overloads. The weak links of such devices include: shear pins and keys connecting the shaft to the flywheel, gear or pulley; friction clutches that do not transmit movement at high torques; fuses in electrical installations; bursting discs in high-pressure installations, etc. Triggering of a weak link leads to the machine stopping in emergency modes.
Safety devices also include brakes. The conditions for their use are varied: often turning off the engine is not enough to stop the moving parts of the mechanism and additional braking is necessary; in other cases, the brake can be used as a kind of movement regulator, for example in the process of lifting a load lifting device; in centrifuges, brakes eliminate vibration at high drum rotation speeds, etc. Braking devices are divided: according to design - into shoe, disc and wedge; according to the method of operation - manual and automatic; according to the principle of action - mechanical, electromagnetic, pneumatic, hydraulic and combined; by purpose - for working, standby, parking and emergency braking.
Fencing devices are a class of protective equipment that prevent a person from entering a dangerous zone. Fencing devices are used to isolate drive systems of machines and units, workpiece processing zones on machines, presses, dies, exposed live parts, zones of intense radiation (thermal, electromagnetic, ionizing), and emission zones. harmful substances and so on. Work areas located at heights (scaffolding, etc.) are also fenced off.
In accordance with GOST 12.4.125-83, which classifies means of protection against mechanical injury, protective devices are divided: according to design - into casings, shields, canopies, barriers and screens; according to the manufacturing method - solid, non-solid (perforated, mesh, lattice) and combined; according to the installation method - stationary and mobile. It is possible to use a movable (removable) fence. It is a device interlocked with the working parts of a mechanism or machine, as a result of which access to work area when a dangerous moment occurs.
To withstand the loads from particles flying off during processing and accidental impacts from operating personnel, the fences must be strong enough and well attached to the foundation or parts of the machines. When calculating the strength of fences of machines and units for processing metals and wood, it is necessary to take into account the possibility of workpieces being processed flying out and hitting the fence. The calculation of fences is carried out using special methods /14/.
Safety devices are designed to automatically shut down units and machines when deviations from the specified parameters occur in their operation or in order to prevent danger for the worker. They are considered according to certain species production equipment.
Reliable fastening of parts on machines is ensured by special devices. When used in devices for clamping pneumatic, hydraulic or electromagnetic devices, guards and blocking are provided to prevent workpieces from flying out during interruptions in the supply of air, working fluid or electric current.
In devices with mechanical fastening, the force exerted by those working on the clamp handles cannot be directed towards the tool in order to eliminate the risk of injury to the hand when it slips. The design of devices in which installation, removal and fastening of parts is performed manually must ensure complete safety during these operations.
When designing and arranging fixtures, it is necessary to take into account the need to ensure free exit and removal of chips from the machine.
The workpieces should be fed to the machine from the side convenient for the worker. At the same time, installation and removal from machines, presses and Vehicle parts, fixtures and tools weighing more than 16 kg must be produced using lifting mechanisms: cranes, trolleys with lifting platforms, etc.
Lifting mechanisms are equipped with devices that ensure reliable retention of the workpiece, product or tool, as well as convenient and safe lifting and installation of them on the machine (Fig. 101).
Rice. 101. Device for installing and removing a cartridge, workpiece, product
Lock is one of the widespread methods of combating injuries and is used on various equipment.
For safety purposes, automatic safety devices are used. locking devices.
Such devices, which fix the working parts of an apparatus element or circuit in a certain (working or non-working) position, are used for:
preventing improper control of the unit or a combination of movements of mechanisms that are dangerous to personnel;
immediate stop of the unit in the event of a danger or violation normal conditions work;
preventing the unit from operating without safety devices;
restricting the movement of mechanisms beyond specified limits, etc. Electrical, mechanical, optical and magnetic connections are used for blocking.
Let's look at the operating principle of a photoelectric blocking device. On the racks of the press or other equipment on the worker’s side there are installed: a photo relay on one rack, and a special electric lamp on the other. A narrow beam of light from the lamp is directed at the photocell, as a result of which an electric current is generated and the drive of the brake mechanism is in the off position - the press is working. When the beam of light from the lamp is interrupted by the worker’s hands, which find themselves in the danger zone, no electric current is generated in the photocell, the effect of the current on the drive of the brake mechanism stops, the brake is activated and stops the press. The diagram of photo relay protection installed on presses with a rigid clutch is shown in Fig. 102.
Rice. 102. Scheme of photocell protection used on presses with a rigid clutch
The dangerous zone at the press is illuminated by beam 1 falling from the lamp onto photocell 3, in the circuit of which there is a relay 7. Contacts 10 and an electromagnet 9 are connected to the circuit through a rectifier 8. When the beam of light crosses, i.e. when in the dangerous zone 2 worker's hands, the photo relay is activated, a current flows through the winding of the electromagnet 9, the electromagnet pulls the rod 11, overcoming the resistance of the spring 4 and brings it under the lever 6, which turns on the clutch 5. The rod 11 is connected to the start pedal 12, which in this position is blocked and the press cannot be put to work.
In Fig. 103 shows a protection scheme using radioactive isotopes.
Rice. 103. Scheme of fencing a dangerous area using radioactive isotopes:
1 - bracelet with an isotope; 2 - screen; 3 - device power supply; 4 - device that perceives radiation from a radioactive source; 5 - rollers creating a danger zone
Blocking of cutter guards, belts, pulleys, gears of machines and equipment is used, in which the latter cannot be activated until their guards are moved to the side and not installed in place.
According to the blocking principle, the following devices are protected: a protective shield on an abrasive machine, which protects the worker from injury from flying particles when sharpening tools and processing products; when the shield is folded down, the engine is blocked and cannot be turned on; the hatch of the crane operator's cabin, which opens to access the top of the overhead cranes - when the hatch is opened, the current supply to all mechanisms and drives of the crane stops; doors of the room in which there is equipment located under high voltage- when the doors are opened, the equipment is de-energized.
On all paths of movement of floor-mounted transport equipment (steel trucks, slag trucks, cast iron trucks, trolleys, etc.), it is planned to install limit switches to automatically turn off the movement mechanisms of the specified equipment (taking into account possible movement by inertia). In addition, limiting stops are installed on all paths of the floor transport equipment.
Each converter rotation drive motor is equipped with a brake, which allows the converter to be held in a stationary position in the event of a power outage. Mechanisms for vertical movement of tuyeres are equipped with switches and stops that prevent the possibility of the tuyeres falling into the converter.
All cranes are equipped with the following safety devices:
stops limiting the movement of the crane, installed on the crane tracks at the ends of the spans, as well as limit switches installed on the crane movement mechanisms, turning off the movement mechanism when the crane approaches the stop at a distance of at least half the braking distance of the movement mechanism;
Limit switches that turn off the movement mechanisms of cranes when they approach each other;
Stops on the crane bridge and limit switches limiting the travel of the trolley;
stops on the trolleys and limit switches that limit the upward movement of the hooks.
The installation locations of safety devices are given in Table 3.2.
Table 3.2 – Safety devices
|
Device name |
Installation location |
|
1.1. Electrified gate valve with remote control 1.2. Explosion safety valves 1.3. Grounding of metal non-current-carrying parts of electrical equipment 1.4. Lightning protection 1.5. Water seals to ensure a reliable seal when the water is turned off 1.6. Devices that provide constant operating oxygen pressure on the low side 1.7. Seals that prevent air leaks on all movable joints of the gas exhaust tract of the converter operating under vacuum 1.8. Stroke limiters for overhead cranes and semi-portal filling machines operating on the same tracks 1.9. Load limiters for all cranes allowing overload of no more than 25% 1.10. Stops to prevent scoops from moving from carts |
At the oxygen outlet there are wires from the workshop manifold to the converter Gas exhaust tract Electric drives of the converter, tuyere, fireplace Gas exhaust tract Gas exhaust tract Oxygen control unit Converter gas exhaust path Semi-portal cranes, filling machines Overhead cranes, semi-portal filling machines Scrap trucks |
The installation locations of blocking devices are shown in Table 3.3.
Table 3.3 – Locking devices
|
Name of funds |
Installation location |
|
1. Converter 1.1. Lock preventing tuyere insertion when the converter is in an inclined position 1.2. A lock that ensures the tuyere rises and the oxygen supply stops when the oxygen pressure in front of the tuyere decreases, the water consumption for cooling the tuyere decreases, or the temperature of the outlet water increases 1.3. Locking mechanism to ensure lifting of the tuyere from the converter in the event of a sudden power outage 1.4. Switches that prevent the lance from falling into the converter 1.5. A lock that prevents lowering of the lance and oxygen supply to the converter when the water supply to the boiler or gas purification is stopped or reduced below the minimum permissible value, as well as when the water temperature, emerging from the caisson above the permissible limit 1.6. Interlock that prevents breaking the boiler skirt in the presence of carbon monoxide in the exhaust gases 1.7. Blocking the gas exhaust tract: Supplying steam to the candle in front of the afterburning device and turning off the gas supply to the ignition burner in the event of an emergency stop of the smoke exhauster or a drop in vacuum to it, as well as in the event of any emergency termination of purge of the melt; Preventing the supply of oxygen to the next melt purge in the event of a malfunction of the pilot burners; Turning off the oxygen supply to the tuyere after the start of its rise when purging is stopped (normal and emergency) 1.8. Interlocks that exclude the possibility of controlling the movement of floor-mounted transport equipment (steel trucks, scrap trucks, sling carriers, etc.) simultaneously from two points 1.9. Interlocks that exclude the possibility of controlling equipment simultaneously from different points (remote control from a computer, local control) 1.10. Blocking, which includes control systems for the smoke exhauster after “ignition” of the melt 1.11. Blocking that prevents the supply of oxygen to the workshop and to the converter in the event of a power outage to the workshop |
Lance lifting and lowering drive Lance drive Lance drive Lance drive Lance drive, oxygen control unit Skirt lift drive Gas exhaust tracts Gas exhaust ducts of converters, units for regulating oxygen supply to tuyeres Oxygen supply control unit, lance lift drive Posts, control panels for floor-mounted transport equipment Equipment control posts and consoles Converter gas ducts Oxygen expansion point. Control units |
Use of fencing.
To create safe working conditions, all open moving parts of the equipment located at a height of 2.5 m or less from the floor level or accessible for accidental touch by workers from service platforms, as well as counterweights not placed inside the equipment, are protected by a solid or mesh fence with mesh sizes 20x20 mm. The guards are removable, resistant to corrosion and mechanical stress.
All fences have interlocks with equipment starting devices, which prevent operation of the equipment when the fence is removed.
All platforms located at a height of 0.6 m or more from the floor level, stairs, open pits, transition bridges, openings in ceilings are equipped with railings or solid concrete and metal fences with a height of at least 0.9 m. It is planned to close hatches, pits, openings with durable covers or decking laid flush with the floor.
In the converter span, the enclosing devices are:
Slag removal panels (under the working platform along the tracks of the slag and steel carriers);
Continuous fencing (converter rotation drive);
Railings with continuous cladding along the bottom (working platform, drive maintenance areas, oxygen supply machine maintenance areas, boiler-cooler maintenance areas, gas cleaning, etc.).
Protection of pipelines from corrosion.
Corrosion is the destruction and corrosion of solids caused by chemical and electrochemical processes. It leads to a loss of strength, hardness, ductility, and tightness, which in turn can lead to accidents.
In the converter span there are gas ducts in which, during converter melting, the formation of deposits during the movement of gas and holes is possible, which can lead to the collapse of the gas duct structures, and, consequently, to accidents and injuries. To avoid this and ensure high corrosion resistance, it is necessary to use special corrosion-resistant materials.
For example, to protect the welded joints of pipelines, it is recommended to use a special corrosion-resistant, heat-resistant material. They are used to line the inner surfaces of pipes. In this case, first the lining is made with a thin-walled sleeve made of corrosion-resistant steel, which is installed offset from the end of the pipes and welded to the pipe body using circumferential seams, and the lining of the inner surface of the pipe between the welded sleeve and the end of the pipe is performed by surfacing a corrosion-resistant material, then inside the surface the pipes include a partially lined surface coated with a heat-sensitive, corrosion-resistant material, such as glass enamel or polymer, and the pipes are joined by welding.
Protection from thermal radiation.
In places where steel carriers, iron carriers with liquid metal, slag carriers with liquid slag pass, as well as in places exposed to heat radiation, thermal protection of the metal structures of the building and equipment is installed. All columns along the path of movement of the steel truck to a height of up to 8 m are lined with refractory bricks, beams and platforms above the steel trucks are protected by special screens made of stainless metal or water-cooled screens (beams above the converter).
To protect the metal structures of the building and equipment located above the converter, complete cover of the converters is provided, which ensures the capture of the torch generated when dumping scrap metal and pouring cast iron. To provide shelter of the required dimensions and to ensure the technology for filling scrap metal and pouring cast iron and in order to remove crane cables from the torch knockout zone, scoops for scrap and buckets for pouring cast iron with elongated toes are provided. To protect workers from radiant heat and possible emissions of smelting products, complete cover of the converters is provided from the zero level to the level above the skirt of the boiler-cooler of converter gases.
The openings in the shelter on the side of the melt drain are equipped with sliding gates.
Converter control panels are located offset relative to the converter neck.
A set of measures is provided for additional thermal protection of the main converter control posts, including glazing the post with heat-absorbing glass, protecting the outer wall of the post facing the converter with reflective screens (aluminum sheets S=1.5 mm), supply of conditioned air to the post from the central ventilation station through a heat-insulated air duct. It is also possible to install a movable protective screen made of polymer film with a metallized coating between the glazing elements. The screen is installed between two window blocks with identical glazing at a distance of 5-20 mm from each glazing element.
Taking samples and measuring the temperature of the metal is provided with a thermal probe without knocking down the converter with automatic recharging of the sensors. For manual sampling, a mechanized trolley with a heat shield is provided.
Maintenance of the steel outlet is provided from a special platform equipped with a protective screen. The glass in the control cabin of the semi-gantry machine is made of durable heat-protective glass and is equipped with special protective screens. The cabin is thermally insulated and equipped with air conditioning.
Construction of aspiration systems.
The flue gases generated during purging in the converter are completely captured, cooled, purified in a wet-type gas purification unit and transferred to the installation for the use of converter gases.
To prevent the knockout of converter gases through technological openings in the boiler-cooler of converter gases, they are cut off by nitrogen ejectors.
To capture fugitive emissions generated when dumping scrap metal and pouring cast iron into the converter, releasing metal, and draining slag from the converter, complete cover of the converters is provided with individual removal of captured gases to the central gas cleaning station of the converter shop.
Protection from noise and vibration.
To reduce noise and vibration levels, it is planned to seal control stations with sound-absorbing lining of the internal surfaces of enclosing structures, and soundproof shelters for noisy units of units.
It is planned to use three-layer panels as enclosing structures for built-in premises and control stations in the converter span. If necessary, the internal surfaces of walls and ceilings are lined with sound-absorbing materials. The joints are sealed using rubber and polyurethane gaskets.
A reduction in noise characteristics from converter bay equipment is provided. Measures are provided for sound insulation and sound absorption at sources of noise and along the path of its propagation.
Complete cover of the converter ensures a reduction in noise levels on the work site and in the span during the melting process. To do this, it is proposed to use a converter casing containing a frame, rear and front panels mounted on it, and two sidewalls forming a convective channel, a lid, air outlet slots, and holes in one of the sidewalls for heating network pipes connected to the heating element. The air outlet slots are made in the cover and the upper part of the front panel in the form of “blinds” type slots, the flanges are bent outward of the casing.
Steel and slag carriers are not sources of increased noise. The only source of noise is the sound siren, which is activated when they move, in accordance with safety requirements.
To protect against vibration, vibration isolating and vibration-absorbing devices are used, as well as remote control, automatic monitoring and alarm devices.
The installation of high-voltage converters is not provided on the cranes of the converter shop, which eliminates vibration of their bridges. The taps are powered through thyristor converters installed indoors on the workshop floor.
Ventilation.
Natural ventilation.
Due to the release of significant amounts of heat, dust (especially fine dust floating in the air) and gases in the oxygen converter shop important for creating favorable conditions labor has organized air exchange. Natural ventilation is the main means of combating industrial hazards. With its help, it is possible to provide enormous air exchanges, sometimes reaching tens of millions of cubic meters per hour. Carrying out such air exchanges by installing mechanical ventilation would require significant costs, large expenditures of electrical and thermal energy, and would be very difficult to operate.
The main advantages of aeration are low (compared to mechanical) costs and noiselessness.
General requirements
Basic technical requirements to the design of safety (locking) devices are given in section 7.2 of STO 34.01-30.1-001-2016.
In accordance with the requirements of the Labor Protection Rules during the operation of electrical installations, safe conditions when working in electrical installations, they must be ensured through the implementation of organizational and technical measures. In this case, when removing the voltage by turning off the voltage of the switching devices, measures must be taken to prevent their erroneous or spontaneous activation.
Fulfilling this requirement can be difficult due to design features equipment, as well as due to the existing risk of erroneous or unauthorized influence on switching devices when using existing blocking and locking devices.
Safety (locking) devices must ensure safe and effective fixation of the disconnected position of the switching device from spontaneous and unauthorized activation, and eliminate the risks of injury associated with failure to comply with the requirements of the technical documentation when preparing the workplace and performing work in existing electrical installations.
In each structural unit of the branch/PO subsidiaries and affiliates that service electrical installations, a list of nomenclature and the scope of equipping repair and repair teams with interlocking devices must be developed. maintenance RU PS, TP/RP and approved by the head of the structural unit.
When performing work on an overhead line by several teams, you should use an extender pad to block the disconnected position of switching devices (LR, etc.) with a working locking device, or use a locking cable on the drives of switching devices, disconnectors with a faulty or missing locking device.
To do this, the work supervisor of each team must install his own lock with a unique key on the extension plate or locking cable, while putting the line and equipment into operation is possible only after all teams have removed their locks.
This method blocking of disconnectors should exclude the possibility of switching on (supplying) voltage to workplaces with possible risks of errors by operational personnel keeping records of the number of crews working on the line, or errors during uncoordinated work in electrical installations and is used, as a rule, in the elimination of mass accidents emergency shutdowns.
Substation equipment of 35 kV and higher with damage identified during accident investigations and during operation, incl. factory defects
Switches type VMT-110B/1250UHL1 (manufactured in 1988), VMT-220B-25/1250UHL1 (manufactured in 1992)
The most common causes of damage to switches such as VMT-110B/1250UHL1, VMT-220B-25/1250UHL1 for the period from 2012 to 2016. appeared:
Destruction of porcelain tire type PMVO-110;
Burnout or turn short circuit of on/off coils;
Violation of tightness (glass, valve, reseal seal);
Damage to arc-extinguishing chambers and insulating rods;
Refusal mechanical parts drive PPrK, el. motor, springs.
Carrying out poor-quality adjustment of controlled parameters during MV repairs also negatively affects the increase in the number of failures of this equipment.
In order to increase the reliability of operation of switches such as VMT-110B/1250UHL1, VMT-220B-25/1250UHL1, the following measures should be taken:
Checking the condition of porcelain covers of VMT type switches 110-220 kV for all types of repairs (current, medium, major) measuring complex MIC 1M or other ultrasonic devices non-destructive testing in order to identify the development of internal defects in porcelain at the initial stage;
Engineering inspections of operating VMT type switches in order to identify defects in porcelain tires;
Use during repairs for setting up a circuit breaker modern devices type PKV, MKI, MIKO, etc. with appropriate training of personnel in methods of working with devices;
When carrying out all types of repairs (current, medium, major), measurement of the insulation resistance of the electric motor winding for winding the springs of the PPrK drive;
Checking the accumulated resources of all VMT type switches and reviewing the period (reduction of the period) for medium and major repairs of switches of this type;
When conducting major repairs replace porcelain covers on switches of the PMVO-110 type manufactured by Uralizolyator (Kamyshlov) with a service life of more than 20 years, replace fixed contacts in the chamber, oil in the switch columns, dismantle and check the pulley mechanism, the integrity of the pulley mechanism body, replace coils switching on and off with a service life of more than 20 years;
Every year, before the onset of the period subzero temperatures outside air, inspect the heating system of VMT type switches.
Voltage transformers 110-220 kV type NKF
(NKF-110-57 HL1, NKF-220-58)
The most common causes of damage to NKF type HP for the period from 2012 to 2016. appeared:
wear, aging of insulation;
depressurization;
manufacturing defect.
In order to increase the reliability of operation of 110-220 kV TN type NKF, the following measures should be provided:
carrying out extraordinary checks of the resistance of the grounding loop of the substation within the time limits established by the technical manager of the branch of the subsidiary and dependent company;
reducing the frequency of testing and thermal imaging monitoring of HP operated beyond the standard service life;
replacement of NKF type VTs with more modern ones (anti-resonance, low oil or gas);
Carrying out at least once every 2 years high-voltage tests of 110-220 kV TN type NKF, which have been in operation for 25 years or more, with measurement of current and no-load losses;
Carrying out chromatographic analysis of gases dissolved in oil at 110-220 kV HP with a service life of 25 years or more at least once every 2 years;
Do not allow the silica gel in the air drying filter to become moist.
Surge suppressors 110 kV type OPN-110/84,
OPN-U-110/84-2 manufactured by ZAO Plant of Energy Protective Devices, St. Petersburg)
During the period from 2012 to 2016, subsidiaries and affiliates of Rosseti PJSC recorded 68 cases of damage to surge arresters of 110 kV and above that had been in operation for less than 5 years, of which in 13 cases surge arresters produced by the Energy Protection Devices Plant in St. Petersburg were damaged.
The main causes of damage to the surge arrester at the manufacturing plant "Energy Protective Devices Plant" in St. Petersburg were:
design defect (11 cases);
atmospheric overvoltage (thunderstorm) - 2 cases.
The most common cases of emergency shutdowns that led to damage to the surge arrester were:
violation of tightness - a defect of the manufacturer in terms of the use of low-quality materials, as a result of which the varistor column was moistened when the sealing of the connection of the upper flange with polymer coating surge arrester;
internal breakdown of polymer insulation caused by a manufacturing defect.
In order to increase the reliability of operation of the OPD manufacturer ZAO Plant of Energy Protective Devices, St. Petersburg, the following measures should be taken into account:
ensuring frequent thermal imaging monitoring and inspection of surge arresters;
organization of measurement and control of the conduction current value;
organization of claims work with ZAO Energy Protective Devices Plant;
