Requirements compounds wires .Connection lived together and attaching them to ELECTROADJUSTING devices must have the necessary mechanical strength, low electrical resistance and maintain these properties during the entire operation.Contact the compound exposed to the load current, cyclically heated and cooled.Changes in temperature and humidity, vibrations, the presence of air in the chemically active particles also have an adverse effect on the contact connection.
Physical and chemical properties of aluminum , from which mainly manufactured wire strands, complicate the implementation of a secure connection.Aluminum has (compared with copper) high fluidity and high oxidizability, thereby forming tokoneprovodyashaya oxide film, which creates a large contact surfaces for t
have copper conductors also formed oxide film, but unlike aluminum, it is easily removed and does not significantly affect the quality of the electrical connection.
large difference in coefficients of thermal linear expansion of aluminum compared with other metals also leads to contact failure.Given this property, aluminum wires can not be compressed into copper thimbles.
during prolonged use under pressure aluminum becomes the property of fluidity, thereby breaking electrical contact, so the mechanical contact of the aluminum wiring can not pinch and in service is required periodically to tighten the threaded connection contact.Contact aluminum conductors with other metals exposed to outdoor weathering.
Under the influence of moisture on the contact surfaces of the water film is formed with the properties of the electrolyte due to electrolysis to form a metal shell.The intensity of shell formation increases when passing through the contact point of the electric current.
particularly disadvantaged in this respect, compounds of aluminum with copper and copper-based alloys.Therefore, such contacts must be protected from moisture or covering third metal - tin or solder.
Connection and termination of copper wires
compound branch copper wires up to 10 mm2 is recommended to twist followed propaykoy, with copper solid wire cross-sectional area of up to 6 mm2, and the wire with a small cross-sectional area of soldertwisting (Fig. 1).Cores cross-sectional area of 6-10 mm2 connected bandage soldering (Fig. 2a), and stranded wires - twisting pre raspletkoy wires (Fig. 2b).
length of connecting points or twisting the binding solder must be at least 10-15 outer diameters of connected living.Solder lead-tin solder with rosin-based flux.Apply soldering copper wires acid and ammonia are not allowed, since these substances are gradually destroying the solder joints.
Connection opressovyvaniem. widely used compound of copper wires opressovyvaniem.The wires cleaned by 25-30 mm, then the copper foil wrappers and pressurized with special pliers-type PC.
Connection and termination of aluminum conductors
aluminum conductor wires are connected by welding, soldering, and mechanical means (Fig. 3).
Weld aluminum wire of special molds using carbon electrodes, receiving power from the welding transformer.
Soldering twisted aluminum wires (Figure 3 c), and then heated in place twisting flame of a blowtorch and propaivayut solders following compositions.
Solder A melting point of 400 - 425 degrees, the composition of zinc - 58-58,5%;tin - 40%;copper 1.5 - 2%.
CH-12 of Mosenergo, the melting point of 500 - 550 degrees;Ingredients: Zinc - 73%;tin - 12%;aluminum - 15%.
technology soldering aluminum wires following:
- all connected with the bare wires, and then clean up loose strands of metallic shine and lapped double strand to form a groove in the place of contact lived.The length of the groove for connections and branches at various sections of veins is shown in Fig.4
- connected by twisting the wire to heat up the flame of a gas burner and a blowtorch to a temperature close to the melting point of the solder.Then rub the groove (with a push) on the one hand a stick of solder connections, pre-entered in the flame of a lamp.As a result, the friction oxide film is torn off, the groove starts to fill up and solder obluzhivatsya as warm junction.Flux is not required.Then obluzhivayut and hocus groove on the other side of the connection.At the same time, and tinned with solder wipe external surfaces and places stranding lived coupling portion;
- soldering wires to be connected to clean up, wipe with a cloth soaked with gasoline, cover waterproof varnish and insulated with electrical tape.
wire termination is performed after their installation. single wire with an area of up to 10 mm2 and stranded with an area of 2.5 mm2 is connected to the current collectors directly.Bare wire at the same time introduced under the clamping screw pin.The ends of the stranded wires are twisted and propaivayut.Depending on the type of end of contact wires can be given a form pistil (Fig. 5a) or ringlet (Fig. 5b).
ends of a solid wire or stranded 10 mm2 cross section of more than 2.5 mm2 supply nozzles (Fig. 5), which are soldered or welded to the core, and in some cases is pressurized.
In all cases the connection branches and wires terminating , the junction of them together and the tip is wrapped with insulating tape in several layers.In accordance with the rules of the dielectric strength at the junction or branching must be not lower than the strength of the insulation as a whole.
In summer conditions for joining aluminum and copper wire between the most acceptable method of connection screw squeezing, because it does not require special tools and equipment.The design of the contact should provide a constant pressure and restrict squeezing wires.Collect the clip when joining aluminum wires with all factory parts (screw clamping washer, flat contact plate), as the absence of any detail will necessarily lead to a deterioration of the contact.
To connect wires to the terminal end of the wire to remove the insulation.The knife held at an angle of 10-15 ° to the surface of the core, it is excluded cut aluminum strands.Wire cleaned to bright metal and quartz-vaseline smeared paste, then folded end cores in the form of rings.Wire must bend clockwise m. E. In the direction of rotation of the fixing screw.
inner ring diameter should be slightly larger than the diameter of the contact screws.
Connection wires by crimping widely used for installation of internal, external wirings and overhead power lines.
This method provides a reliable contact, the required mechanical strength, is easy to implement.The pressure test is performed with hand tongs, mechanical and hydraulic presses using interchangeable dies and punches.
For connecting veins are sleeve GAO, GA, for the termination - tips TA TAM and others.
aluminum wires in connecting sleeve is pressurized by the following technologies:
- pick the type and size of the sleeves, as well as dies and punches in accordancedimensioned sleeves;
- check the presence of lubricant in the factory connectors and terminals, with no lubrication connectors and terminals cleaned and smeared with the brush metal protective
quartz-vaseline vaseline or zinc paste;
- remove the insulation from the ends of living: the termination - a length equal to the length of the tubular portion of the tip, and when combined - over a length equal to half the length of the sleeve;
- trimmed ends of the conductors with sandpaper to metallic luster, wipe with a cloth soaked in gasoline, and cover the quartz-vaseline paste;
- put the prepared strand tip or sleeve;
- when terminating wire is introduced into the tip to the end, and when combined - so that the ends of connected live in contact with each other in the middle of the sleeve;
- set the tip of the tube or sleeve in a matrix, and a pressure test is carried out;
- isolated a compound with several layers of electrical tape.
not permitted on the aluminum wire copper tip pressure test, so the connection is unstable because of the large difference in copper and aluminum coefficient of linear thermal expansion.
pressure test single and stranded copper conductors 4 mm2 and a operate in the copper tube lugs or connection type T copper sleeves type GM.The technology is similar to the copper wire crimping technology crimping aluminum conductors except overlay quartz-vaseline or zinc paste Vaseline.
prohibited conduct molding using a hammer and chisel