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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Electric lighting device. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Lighting According to existing standards in residential buildings with a combined lighting system from any light source, the lowest illumination of a desk, a work surface for sewing and other manual work is 300 lux, and a kitchen table and washing dishes - 200 lux. The average vertical illumination of streets and roads of local importance, village streets should be at least 150 lux. It is forbidden to provide stationary lighting and install sockets in pantries. In lighting devices for light-transmitting surfaces, fireproof materials should be used. In installations with general purpose incandescent lamps with a power of not more than 60 W and fluorescent lamps, the use of Plexiglas and similar materials is allowed. In this case, the distance from the bulbs of fluorescent lamps to light-transmitting surfaces must be at least 15 mm, for incandescent lamps - 100 mm. When installing recessed or ceiling luminaires on ceilings made of combustible materials, the device of which, according to the technical specifications, does not provide for their installation on a combustible structure, the junction of the luminaires to the ceilings must be protected with asbestos gaskets at least 3 mm thick. For lighting undergrounds, basements, attics, storerooms, it is recommended to use incandescent lamps. In technical undergrounds and attics of residential buildings, lighting should be installed only along the line of the main passages. In houses with a height of one and two floors, as well as in houses of gardening associations, attic lighting is not required. Lighting of utility pantries with lattice partitions located in the basements should be carried out with lamps installed in the aisles (without installing additional lamps in these rooms). In living rooms, kitchens and corridors of apartments, provision should be made for the installation of general lighting fixtures suspended or fixed to the ceiling, as well as terminal blocks for connecting lamps, and in kitchens, in addition, hanging cartridges connected to the terminal block. In the toilet, a wall cartridge is installed above the door, and in the bathroom - a lamp above the mirror. In living rooms with an area of 10 m2 or more, it should be possible to install multi-lamp fixtures with the inclusion of lamps in two groups. Multi-lamp luminaires are designed specifically for the purpose of changing the power of the luminaire at will. For this, the lamps of the lamp are divided into two groups, each of which is connected to its own switch. They provide, as a rule, three power modes of the lamp. If, for example, there are five lamps of 60 or 100 W in a chandelier, then one of the lines combines two lamps, the remaining three are connected to the other. As a result, you can change the lighting mode of the room according to your choice: soft diffused light - with two lamps on, calm general lighting - with three lamps on, and bright festive lighting - with all five lamps on. Usually, soft light is used when relaxing, medium - when communicating with the family, for example at dinner, and full lighting - during family celebrations, when meeting guests, during some festive events. The lighting of the rest of the apartment - corridors, hallways, bathrooms and toilets - requires sufficient brightness and clarity, but it is not advisable to install multi-lamp fixtures with two groups of lamps in them. On fig. 52 shows the electrical circuit for connecting a three-arm chandelier to the electrical network.
The scheme works as follows. When the left key of the switch SB is turned on, the electric lamps HL1 and HL2 light up. When the right key of the switch is turned on (the left key is disabled), one HL3 lamp lights up. When both keys are turned on, all three electric lamps light up simultaneously. To ensure electrical safety, the neutral working wire should be connected to the switch as shown in fig. 52. The phase wire must be connected to the common connection point of the electric lamps without breaking its circuit through the terminal block. The phase wire must be connected to the central contact of the cartridge, and the neutral wire must be connected to its threaded part. The hook for hanging the luminaire from the ceiling must be insulated with a PVC tube. This requirement does not apply when hooks are attached to wooden bases. The outer diameter of the half ring at the hook must be at least 3,5 cm. The distance from the overlap (base) to the beginning of the bend must be 1,2 cm. When making hooks from round steel, the diameter of the bar must be 6 mm. The fixture for hanging lamps must withstand for 10 minutes without damage and residual deformations an applied load equal to five times the mass of the lamp (the mass of the lamp in the projects is assumed to be 10 kg). Kitchens should include: - 3 sockets for 6 A for connecting a refrigerator, an over-stove filter, a three-program radio broadcasting speaker and household electrical receivers with a power of up to 1,3 kW; - 1 socket with a grounding contact for 10 A for connecting a household appliance with a power of up to 2,2 kW, requiring neutralization; - 1 socket with earthing contact up to 25 A for connecting an electric stove with a power of 5,8 kW or a household appliance with a power of up to 4 kW that requires neutralization. In kitchens with an area of more than 8 m2, 4 sockets for 6 A should be provided. In bathrooms, showers, toilets, lamp housings and lampholders must be made of insulating material. When installing luminaires with incandescent lamps at a height of 2,5 m or less, it is recommended to use luminaires with recessed sockets with high insulating rings or luminaires with other design solutions that increase maintenance safety. The installation height of luminaires with fluorescent lamps for waterproof use (under the condition of inaccessibility to live parts) is not regulated. It is allowed to use block luminaires with fluorescent lamps up to 40 W without diffusers. The installation height of these luminaires from the floor must be at least 2,2 m to the luminaire body. In individual houses, 6 A sockets should be installed at the rate of: - in living rooms - 1 socket for every full and incomplete 10 m2 of living space; - in kitchens - 2 sockets, regardless of the area. In apartments of residential buildings, three single-phase group lines should be provided: two - for supplying general lighting and socket outlets for 6 and 10 A; the third group line - for connecting household electrical appliances with a power of up to 4 kW and electric stoves. It is not allowed to combine zero conductors of working lighting with zero conductors of evacuation and emergency lighting, as well as zero conductors of lighting and power networks. The device of three-phase four-wire inputs to apartments is allowed with an appropriate feasibility study. On fig. 53 shows diagrams for connecting lamps to the network and a circuit for controlling lamps from two places.
In networks with a dead-earthed neutral with a voltage of 380/220 V, single-phase and three-phase group lines are used to power lighting networks. For zeroing metal cases of lamps, as shown in fig. 53, b, use a neutral protective wire coming from the lighting shield without breaking the circuit with disconnecting devices, and short circuit protection devices are installed in the phase and zero working wire circuits. To simultaneously disconnect the phase and neutral working wires, a two-pole switch is used. If the room has a significant length (for example, warehouses with two exits), it is convenient to use the electrical circuit for switching on lamps from two opposite places (Fig. 53, c). The scheme works as follows. When entering the room from one end, the SBI switch is turned to position "A" (switch SB2 must be turned to position "C"). In this case, the lamps are turned on in the network. When leaving the room from the other end, if you turn the switch SB2 to position "D", the lamps are disconnected from the mains. On fig. 54 shows a wiring diagram made in a one-room garden house, and in fig. 55 - in a two-room apartment.
1 - a room with an area of 6,77 m2; 2 - a room with an area of 11,3 m2; 3 - pantry; 4 - kitchen; 5 - terrace with an area of 7,84 m2. The numbers at the fixtures indicate the minimum required power of electric incandescent lamps. On the wall near the pantry and in the hallway, wall-mounted cartridges with an electric lamp with a power of 25 W are installed. Plug sockets are provided in the kitchen, veranda and rooms. On the branch from the supply overhead line (before the wires are entered into the meter), protection devices are installed (a circuit breaker or two fuses - on the phase and neutral wires). The input is carried out from the overhead line from the end side of the house with an ANRG brand cable with a cross section of 2 x 4 mm2. The group network inside the house is carried out with a wire of the APPR brand with a cross section of 2 x 2,5 mm2 open. The total length of the internal wiring for a one-room house is 27 m, and for a two-room house it is 35 m. The optimum power for a garden house is 1 kW. On fig. 56 shows the wiring in household outbuildings (plan view).
For sheds and pantries, cables of the AVRG, ANRG, AVVG brands should be used. Lighting Everyone knows what applies to lighting devices - these are, of course, ceiling and wall lamps, table lamps, floor lamps, etc. When purchasing a lighting device for a particular room, they are often guided mainly by an aesthetic factor: so that the lamp fits into the overall interior, harmonizes with pieces of furniture in style, color. Less often, the importance of the functionality of the lamp is attached (except when choosing a table lamp). And the economic factor is almost never taken into account. But the concept of rational lighting includes both aesthetic, and economic, and functional, and, if you like, technological factors combined. So what do you need to know when starting the selection of lighting fixtures for an apartment, house, outbuildings, outdoor lighting? First of all, what includes the concepts of functional lighting, economical lighting, what are aesthetic and technological factors. According to the functional purpose, lighting can be general, local and combined. The general type of lighting is used in almost all rooms: living rooms, dining rooms, bedrooms, bathrooms, etc. But options are possible here: - to get a well-lit area of the room (usually the main area), luminaires are used that direct the main light flux down; - to achieve soft lighting of the entire room will help lamps that direct the light flux up to the ceiling. In this case, the light rays, reflected from the surface of the ceiling, are evenly scattered and evenly illuminate the entire room. In general-purpose luminaires, it is possible to use both one lamp with a power of 100-200 W (quite rarely), and several lamps with a total power of 200-300 W (in most cases). Multi-lamp fixtures, in addition to sufficiently bright lighting, allow you to change the lighting power of your choice. The fact is that the lamps of a multi-lamp lamp (usually there are five of them) are divided into two groups, each of which is connected to its own switch (it is for such lamps that two-gang switches are used); therefore, they provide for three power modes of the lamp: two lamps on give a soft diffused light; three work lamps provide calm general lighting; when all five lamps are involved, the lighting becomes bright, festive. Such premises as corridors, hallways, bathrooms and toilets, although they require sufficient illumination, but due to their small areas, they can receive the necessary illumination without the use of multi-lamp fixtures (especially with the division of lamps into two groups). Typically, in rooms of this type, lamps are installed with one, but sufficiently powerful lamp. Speaking about the power of the lamps, it should be noted that with the same total power, lamps with a different number of lamps give a different luminous flux; for example, the luminous flux from three 40 W lamps will be less bright than the luminous flux from two 60 W lamps; and one 120W lamp will give more light output than the same two 60W lamps. In rooms and areas that do not require constant powerful lighting, it is more rational to install lamps with touch switches - electronic lighting power controls (Fig. 57).
You can turn on and off such lamps, as well as adjust the power of the luminous flux, with a simple touch of your fingers to the touch controller. The operating mode of the touch controller is as follows: - a short touch of the touch contact (up to 1 second) turns on or off the lamps; - a long touch adjusts the level of illumination from minimum to maximum and vice versa (the entire range of the lamp is gaining within 5 seconds). Luminaires with a touch control typically use two incandescent lamps of 40 W each (unless otherwise specified in the instructions for the luminaire). And one more subtlety: if when you touch the touch contact, the lamps do not turn on or the illumination is not regulated, then you should unplug the lamp cord from the outlet, turn it 180 °, plug it back in, and then touch the contact again. If the lamp has resumed its normal operation, then the malfunction is related to the polarity of the potentials supplied to the input. If the lamp does not work after changing the polarity of the plug pins, it is necessary to check the integrity of the fuses and, if necessary, replace them. If, after such a manipulation, the lamp does not work, then most likely the touch controller has failed; repair it at home is not possible. Local lighting is used when it is necessary to create a powerful luminous flux in a limited space; such lighting is required quite often: in the kitchen - above the desktop; in the office - for working at a desk or for reading; in the workshop - above the machine, etc. As a rule, in these cases, mainly single-lamp lamps are used, both stationary (wall lamps, sconces) and portable (table lamps, floor lamps). All of the listed fixtures create a sufficient level of illumination only in a small area, so the source of the local lighting flux should be located at a distance of no more than 90 cm from the illuminated area. The power range of the lamps used for local lighting is quite wide: from 60 W (for example, above the kitchen desktop) up to 100 W (for example, over a desk) and even up to 150 W (for work that requires special precision and care, for example, when assembling small mechanisms). Designs of lamps for local lighting can be very diverse. But the most convenient of them are those that allow you to adjust the distance from the light source to the illuminated place and the direction of the light rays, but there is no need to move the lamp itself. As an example of lamps of this type, we can consider a table lamp with a pantograph system (Fig. 58).
The design of this lamp is also convenient because it allows you to fix it not only on a horizontal surface, but also on a vertical one. The stand (leg) of the lamp is divided into two parts by a pantograph system, which allows you to bring the reflector with the lamp closer and further away from the illuminated place. The screw clamp makes it possible to change the direction of the light flux: it can be directed both to the surface of the table, and to the wall and even to the ceiling. A clamp is used as a fixture holder, which has two holes: vertical and horizontal. If the lamp needs to be fixed on a horizontal surface, then the leg bracket is inserted into the vertical hole of the clamp; when fastening to a vertical surface - in a horizontal hole. Attach the clamp with a screw clamp. The design of the stand bracket is such that it provides a 360° rotation of the luminaire. The combined type of lighting is a mixture of general and local lighting; this is the type of lighting used in most rooms in apartments and houses: there is a common lamp that illuminates the entire room, and workplaces (a desk, a desktop in the kitchen, a sewing machine, etc.) are additionally illuminated by local lamps. In rooms with high humidity, contaminated with combustible dust, as well as with high air temperature - in baths, showers, carpentry workshops, saunas, etc. - sealed lamps are used (Fig. 59).
The cover of such a lamp is usually made of heat-resistant plastic. On the inside, a cartridge is fixed on the cover, and the tightness of the wire entry is ensured by a rubber washer. On top of the cover there is a ring for hanging the lamp. The second part of the lamp - the ceiling - is made of thick-walled glass; if necessary, the ceiling is additionally reinforced with a metal mesh, which protects it from possible mechanical damage. The threaded connection of the upper and lower parts of the luminaire prevents moisture and combustible dust from getting inside. On fig. 60 shows different types of fixtures for outbuildings.
Several types of lamps are used for lighting residential, utility rooms, and outdoor lighting: incandescent lamps, fluorescent lamps, mercury arc lamps (DRL). When purchasing a lamp, you should definitely ask what type of lamps are used in it, because each specific type of lamp corresponds to a certain type of cartridge. The most common are electric incandescent lamps; this is facilitated by their low cost combined with high reliability, as well as ease of connection and operation. The principle of obtaining visible radiation (luminous flux) of incandescent lamps is based on the phenomenon of heating a tungsten conductor to a temperature of 2200-2800 ° C when an electric current passes through it. Under the action of such a high temperature, the tungsten filament heats up and begins to glow brightly. Incandescent lamps can be classified according to several criteria.: according to the diameter of the socle, incandescent lamps for general use can be 14, 27 and 40 mm; by rated power - 40, 60, 100 W and more; by voltage range - for use in a network with a voltage of 127 or 220 V; for filling a glass flask - vacuum, gas-filled (argon 86% and nitrogen 14%), with krypton filler (krypton 86% and nitrogen 14%); on a covering of a glass flask - transparent, opaque, milky color, opal. Most of these signs are indicated in the marking of lamps. The letter symbols of the markings are deciphered as follows: V - vacuum, G - gas-filled, B - bispiral, BK - bispiral with krypton filler, MT - frosted flask, ML - milky flask, O - opal flask. The numeric marking symbols indicate the lamp power (in watts) and the lamp supply voltage range (in volts). Despite such a variety of brands of incandescent lamps, their design is the same. Each of the lamps has a glass bulb; it contains two electrodes ending in hooks on which a tungsten filament is attached; the narrow end of the bulb is inserted into a threaded base, the central part of which is a contact. On average, any incandescent lamp is rated for 1000 hours of continuous operation - this is the nominal life. Operating principle low pressure fluorescent lamps (Fig. 61) is based on the conversion of ultraviolet radiation of a glowing electric discharge of electrodes in a gaseous medium into radiation of the visible part of the spectrum.
The phosphor acts as a converter, which covers the inner surface of the glass bulb of the lamp. Fluorescent lamps have a number of undeniable advantages.: - coefficient of performance (COP) is approximately 4 times higher compared to the efficiency of incandescent lamps; - fluorescent lamps are among the most economical, since the heating coils are not used all the time the lamp glows, but are turned on only during its ignition; then they are switched off using the starter; - the brightness of the luminous flux of fluorescent lamps significantly exceeds the brightness of the luminous flux of incandescent lamps; in addition, their visible radiation has an improved spectral composition; - their nominal service life exceeds the service life of incandescent lamps by about 12 times, that is, a fluorescent lamp is designed for 12 hours of continuous light; - The range of colors produced by fluorescent lamps is quite wide, it all depends on the composition of the phosphor coating used in them. However, such lamps are used much less frequently. The limitation of their use is explained by the fact that for reliable operation they require certain conditions: the ambient temperature must be at least 18 and not more than 25 ° C, and the relative humidity of the air should not exceed 70%. The marking of fluorescent lamps is easy to decipher if the meanings of the alphabetic and numeric characters are known. The first letter in their marking is always L, which means "luminescent". The following letters (up to C, indicating the color characteristic) provide information about the spectral composition and design features of the lamps, since their flasks (glass tubes) can be of the most diverse type and size (Fig. 62): B - white, D - daylight, TB - warm white, HB - cold white, E - natural, BE - natural white, F - photosynthetic, R - reflex, K ring, A - amalgam. The numbers indicate the nominal power of the lamp: 6, 9, 11, 15, 18, 20, 30, 36, 40, 58, 65, 80, 125 and 150 watts.
The next type of lamps used in domestic conditions is high pressure mercury arc lamps - DRL (Fig. 63). The action of the DRL is based on the phenomenon of an arc discharge, which in mercury vapor gives powerful ultraviolet radiation. As with fluorescent lamps, the phosphor coating converts ultraviolet radiation into visible light.
The advantage of arc mercury lamps is their efficiency. But the low quality of color rendering limits their scope: DRL lamps are used mainly for outdoor lighting. Lamps work from a network with a rated voltage of 220 and 380 V, and their power can be 50, 80, 125, 250, 400, 700, 1000, 2000 watts. One of the varieties of powerful lamps for lighting open areas are DRI metal halide lamps; their design practically does not differ from high-pressure mercury lamps: the same glass bulb, coated from the inside with a phosphor; a quartz tube, two main tungsten electrodes, two additional tungsten electrodes, and a resistor are placed in its cavity; the lamp is connected to the cartridge by means of a threaded base, and the electric current is supplied through the central - contact - part of the base. The following information can be gleaned from the marking of arc lamps: D - arc, P - mercury, I - with radiating additives, Z - mirror. The first number after the letter symbol is the power rating in watts. Six types of lamps are produced: 250, 400, 700, 1000, 2000, 3500 W. The service life of DRI ranges from 600 to 10 hours of continuous operation. The easiest to connect to the network are incandescent electric lamps (Fig. 64): a zero is connected to the side thread of the cartridge for this lamp, a phase wire of the electrical wiring is connected to its switch, and the wire going from the lamp to the switch is connected to the upper contact of the cartridge.
When the switch is in the "on" position, the circuit is closed and the lamp lights up. As can be seen from fig. 64, c, it is possible to control an incandescent lamp from two places, this is convenient for large rooms, in long corridors, walk-through rooms. By the way, the use of switches in electrical wiring that control lamps from two places is one of the points of the energy saving program. Connecting a fluorescent lamp to the network is more difficult (Fig. 65), since the very process of its operation is more complicated: the ignition voltage must be large enough to break through the gas layer between the electrodes; but as soon as a discharge occurs between them (electrodes), the starting glow must be turned off, since the ever-increasing current strength can simply burn them.
Scheme of switching on a fluorescent lamp in an electrical circuit, in addition to a lamp and a switch, requires a choke, capacitor and starter. The throttle, or PRA (ballast), facilitates ignition and is responsible for limiting the current, which contributes to the stable operation of the lamp. Structurally, the choke is a core made of sheet electrical steel with a winding. The order of inclusion of the throttle in the circuit is in series with the lamp. Factory-made throttles are marked, which contains information about its purpose, device, performance and operating parameters, as well as the state standard code. For example, if the throttle body is marked 2UBI-40/220-AVPP-900, then it should read "two-lamp induction starter apparatus with preheating of electrodes for lamps with a power of 40 W, for connection to a single-phase electrical network with a voltage of 220 V, with a phase shift between currents of built-in lamps, with a particularly low noise level, development number - 900". If the power of the ballast does not match the power of the lamp itself, it simply will not light up. The inductor can be replaced with an incandescent lamp, which will act as a ballast in limiting the current. And in order for the fluorescent lamp to light up more reliably in this case, a wide metal strip of foil is placed on its surface and connected to one of the electrode leads or grounded (Fig. 66).
You can do without foil if one of the mounting current-carrying wires is laid along the lamp itself and fixed to the ends of the glass tube with wire. The starter plays the role of a filament switch after a discharge occurs between the electrodes. In the marking of starters, before the letter C (starter), indicate the power of the lamp for which the starter is intended, and after it - its rated voltage (127 or 220 V), for example: 2 ° C-127 - starter for fluorescent lamps with a maximum power of 20 W inclusive, i.e. 4, 6, 8, 15, 18 and 20 watts; 65С-220 - starter for 65W fluorescent lamps. But if the marking indicates 8 ° C-220, then this means "a starter for fluorescent lamps with a maximum power of 80 W inclusive, with the exception of lamps with a power of 65 W, that is, 13, 30, 36, 58 and 80 W." The starter is connected to the electrical circuit in parallel with the fluorescent lamp. For connection, the starter has contact pins that are inserted into the sockets of the starter holder, after which the starter is turned clockwise until it stops. The lamp itself is connected to the cartridge with pins located at its ends - contact electrodes: the pins of both socles are simultaneously inserted into the slots in the upper part of the cartridge until it stops and the lamp is carefully turned 90 °. As already noted, fluorescent lamps are very capricious in terms of humidity and ambient temperature. So, if the relative humidity reaches 75-80%, they may not ignite; a similar trouble occurs at temperatures outside the range of 10-35 ° C. A thin conductive strip (for example, made of metal foil) glued to the lamp bulb and grounded or zeroed, or coating the glass bulb with a layer of hydrophobic transparent varnish, can help here. The fluorescent lamp mechanism also responds to a 10% decrease in mains voltage, which should also be taken into account when choosing a luminaire with fluorescent lamps as a lighting device. If the base of the incandescent lamp (it doesn’t matter whether it is an independent light source or used as a ballast when the fluorescent lamp is turned on) is rusted to the cartridge and the lamp in the cartridge is jammed, then unscrew the lower part of the cartridge along with the lamp, turning off, of course, the circuit breaker first or removing plugs. The resulting one-piece connection cartridge - base can be separated by breaking the flask and using pliers; but there is no point in this, because further operation of a rusted cartridge is not recommended. A similar trouble can happen with a fluorescent lamp, and here you should be especially careful not to damage the glass tube, since it contains mercury vapor - a dangerous and potent poison. In general, most of the malfunctions of a fluorescent lamp cannot be corrected at home, and only some of them can be eliminated on their own (Table 7). Table 7. Fluorescent lamp malfunctions; their causes and how to eliminate them
In the circuit for connecting an arc mercury lamp to the electrical circuit (Fig. 67), there is no starter, since it is not necessary to turn off the filaments after a discharge occurs between the electrodes.
However, a capacitor and a choke are necessary: the capacitor is connected in parallel with the lamp, the choke is connected in series. And now some useful tips about the installation, operation and repair of lighting fixtures and light sources (lamps). The first advice has already become traditional: before you install the lamp, mount it in the electrical network, inspect for troubleshooting and repair, you must unscrew the fuses (plugs) on the switchboard or meter or turn off the circuit breakers. It is preferable to carry out all of the above work during daylight hours, using natural light. If the room in which you have to work does not have natural light or you need to make urgent repairs, then you can use autonomous sources of lighting: electric lamps on batteries, lighting lamps powered by a car battery, etc. Before connecting a lighting fixture to the electrical circuit, you need to find out what condition the wiring is in at the connection point, and whether there is a hook for the chandelier. One of the disadvantages of almost all luminaires with incandescent lamps is that the terminals are too close for connecting opposite-pole wires, so you should carefully ensure that the wires suitable for the chandelier terminals are securely isolated from each other. The vast majority of ceiling lights (chandeliers) have decorative caps on the stem that cover the wires, hanging hook and terminal block (some of the caps are equipped with screws for fixing in the up position). The length of the hanging hook should be slightly less than the length of the decorative cap so that the latter completely covers the terminal block and wires. Hooks are available in several types - for each type of ceiling (monolithic structure, hollow-core slabs, etc.). It is desirable that the ends of the hook have insulating caps; if they are absent, then the ends should be insulated with a specially designed tape. When replacing faulty lamps in a luminaire, it is necessary to ensure that the type and power of the new lamps correspond to the parameters of the electrical wiring and the lighting fixture, for example: if you install an incandescent lamp with a higher power than that for which it is designed, this will certainly cause overheating of the contact connection cartridge - plinth, which can cause a new malfunction, even a fire is possible. Author: Korshevr N.G.
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Comments on the article: Anton That's just not said about the repair of lamps with DRL lamps ... Sergei Something new in the circuit breaker. Fig.52. Who taught you to put the phase directly into the circuit, and zero through the switch?
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