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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Electrical products. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Electric installation work Wiring called products that allow the installation of electrical wiring. These include: dowels, brackets, strips and buckle strips, XBT electrical tubes made of PVC compound, GAO sleeves, insulating caps made of polyethylene, hooks for hanging fixtures, insulator TF-16 (telephone porcelain), porcelain bushings, funnels, cable end tips (Fig. 12).
dowel indispensable for the installation of electrical wiring. They are intended for fastening support structures, boxes, elements of open electrical wiring, etc. and are divided into steel nail-shaped manual driving of the DGR type, plastic and expansion, with a fibrous filler. Dowels for manual driving (DGR) they are produced with a rod with a diameter of 3,5 mm, a length of 25, 35 mm, and in recent years, dowels with a length of 100 mm or more have appeared. The allowable load on the dowels is 100-800 N (10-80 kgf). The base of the dowel is hammered with a hammer or using a mandrel. Dowels types U656-U678 are a plastic sleeve in which a bolt or screw is installed. The dowel is fastened in the socket by means of a sleeve when a bolt or screw is screwed into it. Parentheses various brands are used for fastening flat wires and cables with a cross section of up to 6 mm2 with open and hidden laying. Brackets are attached to brick or concrete bases with dowel-nails with a diameter of 3,5 mm using a mandrel. Strips and buckle strips are used for fastening cables and wires to building bases in open laying. Under the wires, insulating pads of electrical cardboard or similar material are placed so that it protrudes on both sides of the strip. Wiring tubes XBT made of polyvinylchloride compound used for insulation of wires and cable cores. The inner diameter of the tube is indicated in the designation and is 3, 5, 6, 8, 10, 12, 14, 16, 18, 20 or 22 mm, wall thickness - from 0,4 to 1,15 mm. Sleeves GAO used for connecting single-wire conductors and wires and cables with a cross section of 2,5-10 mm2. The sleeves are aluminum tubes, the inner surface of which can be factory lubricated with quartz-vaseline paste. Caps insulating ones made of polyethylene are designed to insulate the joints of wires with a cross section of up to 4 mm in junction boxes of electrical networks. The joints made by twisting, welding or crimping in sleeves are lubricated with glue or bituminous mass to securely fasten the caps on them and protect them from corrosion, then they are put on insulating caps. Hooks for hanging fixtures (Fig. 13) is selected depending on the design of the floor slabs. In reinforced concrete floors with voids, the so-called "breaking" hooks of the U623, U628 types are installed: the hook rocker is vertically installed in a hole punched in the floor slab; under the action of gravity, the rocker turns and occupies a horizontal position in the void of the ceiling, securing the hook. Hooks with wood carvings are screwed into wooden floors. In the conditions of summer cottage construction, in the absence of factory-made hooks, home-made ones are used. The dimensions of the hook for hanging household lamps: the outer diameter of the half-ring is 35 mm, the distance from the ceiling to the beginning of the bend is 12 mm, the diameter of the rod when making the hook from round steel is 6 mm. The half ring of the hook, made of a rod with a diameter of 4 mm, begins to unbend at a load of 500 N (50 kg). On such a hook you can hang lamps weighing no more than 10 kg.
Metal hooks are isolated by putting a PVC tube on them. Hooks screwed into wooden floors do not need to be insulated. Hook KN-16 (made of steel) is used in the construction of inputs to the building. At the pin end of the hook there are nine protruding ruffs or notches 0,7-1,2 mm high, evenly spaced along the circumference in three rows and facing down with their points. During installation, the hooks are screwed into the support with the entire threaded part plus 10-15 mm. Holes are made to a depth of 0,75 of the length of the threaded part. Insulator TF-16 (telephone porcelain) is installed on the hook pin using a polyethylene cap. In the absence of caps, the insulator is screwed onto the pin part of the hook, onto which an even layer of tow is wound along the thread. The insulator is screwed on to the end, and then unscrewed by half a turn to prevent splitting of the insulator when exposed to wind loads. Porcelain bushings different standard sizes (VTK-9, VTK-11, VTK-13, VTK-16, VTK-18, VTK-20, VTK-23, VTK-30) are designed for terminating insulating tubes at the exit from walls and ceilings, as well as for protect wires and cables from damage. The numbers following the letters in the designation of the bushings indicate the inner diameter of the bushing in mm. Funnels V-2, V-6, V-10, V-16, V-25, V-35 are used to make inputs from the outside of passages into damp and especially damp rooms, and are also used when bypassing obstacles with open wires and for leading wires out with hidden laying. In wooden walls, bushings and funnels are tightly inserted into the holes made with a drill. Cable end lugs (Fig. 14) are designed for terminating copper stranded conductors with a cross section of 1-2,5 mm.
On the cores, the end pieces are fixed by crimping. Insulating tape is designed to insulate conductive parts. The most commonly used rubberized single-sided tape with a width of 10, 15 or 20 mm. The basis of the insulating tape is a cotton fabric impregnated with an adhesive composition. Electrical installation products also include junction boxes, power boxes, apartment shields. Branch boxes (Fig. 15) are designed for branching, pulling and connecting wires with open and hidden laying and are metal or plastic cases closed or with metal plastic covers. Some boxes have thinnings that are broken out at the installation for the entry of wires, or notches. For concealed wiring performed by APPV wires and similar, boxes of types U197, U198, U419, U191 are used. For open wiring made with flat wires and APRF wire, boxes U191, U194, U419 are used, and for wiring made with AVVG, ANRG cables, boxes KOR-73 are used.
Boxes and embedded rings for installing switches, switches and socket outlets with hidden wiring are a metal or plastic case. Embedded rings are embedded in wall panels at house-building factories, but they can also be installed during installation. Power boxes (Fig. 16) serve as introductory devices for protecting electrical receivers and distributing electrical energy, as well as for operational shutdowns.
In construction, boxes YaVP2-60 and YARVM-6122 are often used. You can also use other boxes of a similar design, such as YARP11-302 or YaBPVU-1m. Boxes are produced for operation at air temperatures from -40 to +45 °C or from -10 to +40 °C. The boxes are mounted on the wall on the outside of the house in a vertical position, the knife switch handle is usually located on the right. It is allowed to deviate the box from the working position up to 5° in any direction. Typically, the design of the boxes ensures that the circuit breaker is interlocked with the lid in such a way that when the circuit breaker is on, the lid cannot be opened, and when the lid is open, the circuit breaker cannot be turned on without breaking the lock. The boxes allow entry and connection from above or below of armored and unarmored cables and wires in pipes with aluminum or copper conductors with rubber or plastic insulation with a conductor cross section of up to 50 mm per phase at a rated current of 100 A. When connecting buildings to the electrical network in a chain (Fig. 17), the box is connected as follows: two wires are connected to the input terminals of the knife switch. The cross section of the conductor connected from the first box to the next one is no more than half the cross section of the conductor connected to the first box from the network side.
In houses of private construction and in apartments, so-called apartment shields are used. Housing shields designed for distribution and metering of electrical energy, as well as for protection of outgoing lines in case of overloads and short circuits. Shields are operated at ambient temperature from + 1 to +40 °C, relative air humidity up to 80% at 25 °C and at lower temperatures without moisture condensation in an environment that does not contain gases, liquids and dust in concentrations that disrupt operation shields. The operating position of the shield is vertical, with a deviation of no more than 1°. On the shields, automatic front-mounted circuit breakers of types AE 1000, AB-25, VAN with a rated current of releases of 16 and 25 A or single-pole threaded fuses, a batch switch used as an input device, and a counter are installed. Some shields are made with a zero bus, which has clamps for connecting copper or aluminum conductors with a cross section equal to the cross section of the phase wires. Single-pole threaded fuses consist of a base with a cover, fasteners and fuse links. Factory-made replaceable fusible inserts are porcelain or glass tubes filled with sand, on the ends of which metal caps are put on, interconnected by a fusible bridge (calibrated wire). Rated currents of fusible inserts of version I - 6 and 10 A; executions II - 6, 10, 16, 20, 25, 40 and 60 A. When passing through the fuse-links a current exceeding 1,6-2 times the nominal one (depending on the version), they melt within 1 hour, when currents pass, short circuits work immediately and interrupt the electrical circuit. If a fusible link burns out, it must be replaced. To do this, fusible links are installed in the fuse head (Fig. 18). Heads of execution II have operation indicators. A contact plate is fixed on the porcelain base of the fuse, one end of which is placed in a control porcelain sleeve with a hole in the center. The diameter of the hole is made in such a way that a fuse-link of only a certain diameter enters it (the diameter of the insert is determined by its rated current): the larger it is, the greater the rated current. The 6A fuses have a hole diameter of 7mm and can accommodate a 6mm fuse link. It will not be possible to install a fusible link with a rated current of 10 A, the diameter of which is 8 mm, into such a fuse, since the design of the control sleeve will not allow closing the electrical circuit, which prevents possible errors during operation and installation. Control sleeves in fuses for a rated current of 20 and 60 A are not installed. Control sleeves and indicators operations are colored depending on the rated current of the fuse-link. So, for 10 A, the sleeve is blue, for 15 and 40 A it is green, and for 6 and 25 A it is not painted.
Protective equipment of the power system of the house are fuses and circuit breakers. Threaded fuses PAR-6,3 or PAR-10 series have a number of advantages over fuses: they provide better protection, do not require replacement, and are easy to operate. Automatic fuses have thermobimetallic and electromagnetic releases that protect electrical circuits from overloads and short circuit currents. With the passage of a current that is 2 times higher than the rated current, the fuse operates within 2,5 minutes. The electromagnetic element has a cut-off (instant shutdown) at 7-10 times the current in relation to the nominal. Automatic switches (Fig. 19) AB-25 m and AE-1000 are designed to protect single-phase lighting networks from overload and short circuit currents, as well as to turn these circuits on and off manually. The AE-1031 circuit breaker consists of a base, a cover, a free trip mechanism, an overcurrent release (thermal, electromagnetic or combined) and an arc extinguishing device, which is a chamber with a deion grating made of steel plates. The electromagnetic overcurrent release only trips in the event of a short circuit without a time delay. The electromagnetic release contains a core, an armature and a return spring. In the event of a short circuit, the armature is attracted to the core and acts on the tripping element, causing the circuit breaker to operate (open) quickly. The thermal release trips with a time delay inversely dependent on the current in case of overloads and short circuits. Automatic circuit breaker AB-25 m has a thermal release, the bimetallic thermoelement of which is connected in series with the switching contact system. In the event of short-circuit currents or overload, the thermoelement bends, while releasing the lever of the shutdown mechanism; switch trips, contacts open. The rated currents of the releases are set at the factory and are not adjusted during operation. The release settings cannot be changed. In case of overload or short-circuit currents exceeding the tripping current setting, the contact system is switched off automatically, regardless of whether the control handle is held manually or not. In other words, the mechanism of free tripping of the switches provides instantaneous closing or opening of the contact system during automatic or manual control.
Control handle positions: I - on; II - the switch is turned off automatically; III - manual shutdown; IV - platoon for automatic operation The automatic opening of the switches is indicated by the control handle, which is set to the appropriate position. To close the circuit breaker after tripping, the handle must be moved to the cocked position for automatic operation, and then moved to the "on" position. To protect against overvoltage (through fuses and circuit breakers) and to account for consumed electricity, they use counters. They are single and three phase. Install the meter in accordance with the requirements of the PUE. At the place where the meter casing is attached, there must be a seal with a stamp indicating the period of its verification. When installing three-phase meters, the seal should be no more than 12 months old, single-phase meters - no more than 2 years. The appearance of the counters should indicate the correctness of its storage. The cover of the block for connecting wires is sealed by the service of the network owner when the meter is admitted to operation or when it is replaced. The consumer is responsible for the safety and integrity of the meter and seals on it. The owner of the networks ensures the planned replacement of meters accepted for service within the time limits established by the State Standard. In case of violation of the wiring to the meter and its damage due to the fault of the consumer, the consumer pays for the repair, replacement and verification of the device. In addition, the energy supply organization has the right to demand the purchase of a new electric meter to replace the damaged one. For normal operation of the meter, the following requirements must be met:
For safe installation or replacement of the meter, it is necessary to provide for the possibility of disconnecting the supply wires. The distance from the meter to the switching or protective device that turns it off should not exceed 10 m. Usually, the input device meets this requirement, but it is better to use a batch switch on the shield that is common with the meter. A single-phase branch requires a 220 V single-phase current meter and a rated current of 5 or 10 A. The single-phase meter is designed for direct metering of energy consumed in single-phase AC circuits with a frequency of 50 Hz and is designed to operate at a rated voltage of 127 or 220 V. Rated voltages (127 or 220 V), currents (5, 10 or 20 A), overload capacity , the meter constant is indicated on its label. The meter's label also indicates the highest allowable current, which is 3-3,5 times the nominal current, for example, for a 5 A meter, the maximum allowable current is 15-17 A, for a 10 A meter - 30-34 A. With a three-phase branch, a three-phase meter is used for a four-wire network with a voltage of 380/220 V at 5 or 10 A. In this case, it is allowed to use three single-phase meters for 220 V. The wiring from the input device to the shield with the meter is carried out with a cable or insulated wires in a metal pipe without any or splicing, soldering and other violations of the integrity of the wire. The cross section of the conductors is taken depending on the power of the current collectors, but not less than 4 mm2 for aluminum wires and 2,5 mm2 for copper wires.
If the owner of the electrical network does not specify the maximum allowable current, then the protection in the input device or on the branch must cut off the current that exceeds 25 A for a long time, i.e. the rated current of the fuse-link or the installation current of the circuit breaker must be 20 or 25 A. When installing the electrical wiring connected to the meter, it is necessary to leave the ends of the wires with a length of at least 120 mm. The insulation or sheath of the neutral wire for a length of 100 mm in front of the meter must have a distinctive color. Depending on the location of the premises in the house, wiring from the input device to the meter can be carried out both along the outer walls and inside the building. The passage of the pipe through the wall is sealed with bitumen or cement-alabaster mortar. To protect the wire (cable) at the point of its passage through the wall, a piece of metal or plastic pipe is used. A funnel is put on the ends of the pipe from the outside, and a sleeve from the inside. Protection against moisture penetration is provided by bituminous filling. Metering and distribution boards are attached to the wall or installed in a niche (in stone buildings). Single-phase shields are produced with and without a switch, for two and three outgoing groups, with threaded fuses (plugs) and automatic switches. Widespread single-phase shields of previous releases with protection devices in both outgoing wires are dangerous to use in electrical wiring, and in household conditions it is unacceptable. Three-phase metering and distribution boards (Fig. 20) are produced with switches on the input side, and there may be fuses or circuit breakers on the outgoing lines. Author: Bannikov E.A.
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