Welding of a copper wire: an overview of methods and equipment. Soldering or welding copper wires - which is better?

The most important task when connecting any electrical contacts is to ensure their minimum resistance. With poor contact, the resistance between the copper wires is significantly increased, resulting in the heating of the cable. There are many ways to connect the contacts, but the most reliable and effective right is considered to be welding of the copper wire. This technology allows the monolithic connection of all wires of the wire, thus achieving the lowest possible electrical resistance. As a result, the heating of the wires is eliminated, hence the level of fire safety is significantly increased.

Wiring Methods

Copper is the main material of conductors. Due to the physico-chemical properties of this material (high plasticity, lack of elasticity), working with it has its own characteristics. The rules for the installation of electrical installations stipulate that the operations for connecting, branching and terminating the conductors of cables and wires can be carried out by soldering, welding, crimping or clamping (bolt, screw, etc.). Each of them has its own peculiarities, which will be discussed below.

Connecting wires by twisting

Simple wire twisting is prohibited by the PUE because it is the most inefficient, short-lived and fire-dangerous connection. Despite this, the home craftsmen never stop using this method, although the consequences of such "needlework" can be the most smooth.

Twisting wires has one important drawback: copper connections with time deform and weaken, eventually finally breaking down due to the high resistance of the transient.

It should be remembered that the twisting method can be used only in exceptional cases, if it is necessary to restore power supply urgently, and other methods are inaccessible in a particular situation. It is very important to take care of the quality, safety and reliability of the connection.

Strictly forbidden:

• Connect wires made of different materials (aluminum and copper);
• Connecting copper solid wire with stranded.

The process of twisting is as follows:

1. Clear the wires from the insulation at a distance of 6-8 cm from the edge;
2. Put one wire on the other criss-cross and tighten as tightly as possible. If the cross-section of a copper wire is more than 1 square. Mm, this operation is performed using pliers.
3. Bite off the remaining ends of the wires with the wire cutters.
4. Isolate twisting with special insulating materials (PVC or heat shrink tubing, caps) or several layers of insulation tape. Insulation must necessarily capture the insulating layer of wires.

Crimping

This method is a process of connecting the wires by crimping them with a special tubular sleeve or a tip. These devices are used if the cross-section of a copper wire is 2.5-240 square meters. Mm. The undoubted advantages of crimping technology are the speed and accuracy of the work, as well as the subsequent durability and safety of the joints.

For crimping, a special tool is used - mechanical, hydraulic or electric pliers or professional pressing presses. The selection of sleeves is carried out taking into account the cross-section and the number of wires to be connected.

After removing the insulation and stripping of the veins, they apply a quartz-vaseline paste, put the sleeve on and crimp it. Pressed liners are insulated.

Crimp terminals and terminals

The use of various crimps and terminal blocks is quite common when connecting electrical outlets, switches, lighting devices, and when installing switchboards. These devices allow the copper wire to be connected neatly and quickly, however, the multicore wire without preliminary soldering or crimping can not be clamped into the screw clamp.

The undoubted advantages of screw clamps include the possibility of connecting aluminum wires with copper wires, as well as the absence of the need for subsequent isolation of contacts.

However, this type of connection is not devoid of shortcomings. It needs periodic maintenance, which consists in twisting the clamping elements. Copper is a very soft material, prone to "leakage" from under the load. Even if the connections are made through rigidly spring-loaded self - clamping terminals, because of the too small area of the contacting surfaces under heavy load, the spring elements are heated and released, so that their elasticity decreases along with the quality of the connection.

Soldering of VS-welding

To ensure a good contact, soldering or welding of copper wires is most often used. What is the best of these methods? Definitely, welding. The matter is that soldering is a rather laborious and time consuming process, especially if you want to connect a copper stranded cable. In addition, adhesive compounds are destroyed over time due to the presence of a third, more friable and low-melting metal - solder. The presence of a transient resistance in the joints of different alloys contributes to the appearance of destructive chemical reactions and other negative processes.

When the copper wire is welded, the concept of "contact" disappears altogether, since the connection is made monolithic of the same type of metal. Naturally, such compounds are distinguished by a record low resistance, due to which heat is practically not released.

Soldering

It should be noted at once that this operation requires certain knowledge and experience. Paradoxical as it sounds, but quality twist is better than bad soldering, remember this.

The soldering process begins with the preliminary cleaning of the ends of the wires from the insulation and oxides. Then they are twisted, covered with a special substance - flux, then they are pressed. It is possible to solder not only wires from copper, but also from aluminum, the main thing is to choose the flux and solder correctly. The use of active acid flux is not recommended, as it will necessarily remain on the wires, resulting in the connection quickly breaking down.

One soldering takes a lot of time, but if done correctly, this connection will be reliable and durable. After the wires cool, they must be carefully insulated.

Welding

The most qualitative and safe connection is the welding of a copper wire. Resistance in the place of contact of wires does not exceed the index of their standard resistance. This method does not take much time and is considered relatively simple. With minimal skills and knowledge, welding copper wires at home is perfectly feasible.

When carrying out welding operations, all fire and electrical safety rules must be strictly observed. To avoid burns and eye injuries, personal protective equipment should always be used - special protective clothing and gloves, a welding mask or goggles.

Equipment for welding

The connection of wires by welding is carried out by apparatuses of various types. It is most convenient to use an inverter apparatus for welding copper wires, since devices of this type are characterized by small dimensions and weight, economical power consumption and a wide range of adjustments of the welding current. Their advantages include the ability to provide a stable burning of the electric arc.

If a significant amount of electrical work is planned, then the purchase of an inverter-type welding machine will be quite reasonable and justified. In addition, this equipment certainly will not be a "dead weight" in the future.

Features of the welding process of copper wires

Welding of a copper wire can be carried out both variable, and a direct current at indicators of pressure of 15-30 Century It is very good, if in the device possibility of adjustment of a current is provided.

For example, to weld two copper wires cross-section of 1.5 square meters. Mm, enough 70 A. For welding three wires with the same cross-section, the current must be increased to 90 A. The connection of three wires cross-section 2.5 square meters. Mm it will be required from 80 to 100 A, and for welding of five similar wires - 120 A. If the optimum welding current is chosen, the electrode "sticking" does not occur, and the arc burns sufficiently steadily.
For welding wires from copper, use copper-copper "pencils" (electrodes). If there are none, then it is possible to use carbon rods from finger-type batteries.

Welding technology

The tips of the wires 5-6 cm long are cleaned from the insulation coating and twisted, starting from the insulation slices, leaving 5-6 mm at the end of the twist in untwisted form. These tips need to be straightened, folded in parallel and pressed against each other. When twisting three or more wires, at the end you still need to leave only two free tips, and the others cut off at the place of the last twist of twist. If the welding machine is not powerful enough, this twist will make it easier to form a melt ball. If there is enough welding current in the machine, you can make a simple twist.

Further, the twisting is clamped by means of a welding clamp. If this device is missing, you can use the usual old pliers.

The prepared joint is welded with a carbon electrode. In the process of welding copper wires, the ends left untwisted are melted prior to the formation of the melt ball. To ensure reliable mechanical and electrical contact of the wires, the melting zone must necessarily go to twisting.

The duration of welding should not exceed 2-3 seconds, otherwise the insulation of the wires will melt. After complete cooling of the connection, it is insulated with several layers of electrical tape or special caps, PVC or heat shrink tubes.