The welding cable is used for arc welding connections using semi-automatic or automatic welding machines. In this article we will reveal the classification of welding cables, how to choose a welding cable, what to look for when choosing what should be the core of the welding cable, the cross section of the welding cable, cable flexibility requirements and whether to extend the welding cable on the inverter. Yes, you will be able to pick up a cable for the welding machine which will be comfortable to work at any air temperature, and the electric highway will be able to maintain the set loadings.
There are often situations when it is necessary to replace the old welding cable with a new one, or the inverter was accompanied by too short or poor quality welding cable, when there are cases that often come with copper-plated cables or low copper content of 60-70%. Then there is the question of choosing the brand of cable for the welding machine.
The length of the welding cable can be different, it is selected in each case separately. Some people manage to carry the device on their shoulders, this is not a good practice, as there is still a high voltage inside the device. This is most often practiced by amateurs who do not know what a normal job is (this is when you have one handle in your hand and you do not need to carry all the equipment with you constantly).
The recommended cable length according to the textbook should not exceed 40 m. Despite this, there are examples of using a 16mm 2 x50m cable on a 400A transformer and no losses, ignition interruptions and problems with arc burning are observed.
So let’s move on to the main, because the welding cable experiences increased loads both from the device and from external factors (construction conditions, friction on the ground or concrete, heating, frost), the correct choice depends on its service life and efficiency. At first it is necessary to understand, what there are welding cables and in what their differences, we will consider below not the full but basic list:
1.) Cable КG: (Deciphered as “flexible cable”) – this is the most common type of cable. Ideal for operation with direct current up to 1000 W or with alternating current up to 600 V and a frequency not exceeding 400 Hz. The wire is used to connect the inverter to the 220 or 380 V mains, as well as to connect the electrode holder and the ground clamp.
2.) Cable KOG: (Deciphered as “especially flexible cable”). Unlike KG cable, it uses a thinner core diameter, so the cable is especially flexible. As a result, the turning radius is smaller. This is especially useful when welding in hard-to-reach places, when the welder needs to bring his hand with the holder at an awkward angle. It is also practical when working at height, where you need to wind the cable on your hand (to make it easier to hold) – then the loops will not protrude strongly on all sides. Unlike CG, it is designed to pass 220 V with a frequency of 50 Hz.
3.) Cable KGN: (Deciphered as “flexible non-combustible cable”) – such a welding cable with the addition of the letter “H” means that the material is non-combustible. The insulating shell is made of heat-resistant material that can withstand temperatures over 200 degrees. This wire will be needed if you have to conduct electric welding / cutting literally in a flash (the needs of the Ministry of Emergencies, repair crews on ships, etc.). In the domestic and industrial spheres it is practical when the design is going big, and the welder needs to move on just welded sites for continuation of work. Then the cable will not melt when it touches the newly heated metal.
4.) Cable KG-HL: (Deciphered as “flexible cold-resistant cable”) – the marking of this cable contains the letters “XL”, which imply permitted operation in the cold. To do this, a special rubber is added to the insulation. This allows you to maintain flexibility at temperatures down to -60 degrees, so it is especially suitable for work in cold weather and severe frosts. If you often have to conduct welding in the winter on the street, then pay attention to products marked KG-HL.
5.) Cable KGT: (Deciphered as “flexible tropical cable”) – this type of cable can withstand temperatures up to +85 degrees, which is the optimal solution for operation in hot environments. The insulation actively resists fungi and mold, and the cable is suitable for working in humid warm conditions.
And now the main emphasis on the two main welding cables in the choice of the most in demand and reliability (if without additional specifics), it is KG and KOG.
The difference between a welding cable KG and KOG. Visually the design of a welding single-core cable KG and KOG is similar and there would be no difference between them:
KG and KOG cable design:
– multi-wire copper core, ie consisting of individual wires.
– Synthetic film on the core (visually similar to polyethylene, cellophane).
– Rubber insulation
– Rubber shell
– In the COG cable it is possible to impose a common insulating and protective sheath with a greater thickness (not less than 2-3 mm)
However, the differences between KG and KOG welding cables are quite significant, and this is the class of flexibility:
KG welding cable has the 5th class of flexibility, and KOG – the 6th. What does it mean?
This means that the diameter of the 6th class wires is thinner than the 5th class. For example, in KG 1×16 the diameter of the wires is 0.41 mm, and in KOG 1×16 – 0.21 mm, so KOG 1×16 is more flexible and softer. In this regard, the minimum bending radius of the KOG is smaller, which means that it can be bent more at the angle you need. The KOG cable is more flexible in comparison with the KG cable.
The weight of 1 m of KOG 1×16 cable is 240 g, the weight of KG 1×16 is 310 g. The longer you choose the welding cable, the heavier it is. Given that the length of the welding cable can reach 40 m, the difference will be several kilograms.
Different voltage parameters:
The KG cable is designed for up to 660 volts at AC voltage (up to 400 Hz), and KOG – up to 220 volts and 50 Hz.
Now, after reviewing the characteristics, let’s move on to a practical approach when choosing a welding cable.
The cable cross-section must be selected based on the parameters of the maximum current of the welding machine.
It is necessary to follow the “golden” rule – the higher the current in the welding machine, the greater the cross section of the cable should be purchased. It is important not to overdo it, because with insufficient diameter of the cores, the equipment may simply not start. At the same time too thick welding cable is an extra expense and excessive loading for the welder who is compelled to move constantly with a wire.
To perform relatively small welding tasks, especially for household matters, it is enough to use inverter-type equipment, which is compact and affordable. The cable cross-section parameters for a welding inverter with different current characteristics must be as follows:
|Current, Ampere||Cable cross section, mm²|
|330-400||1х100 and 11х50|
|500-600||1х120 and 11х95|
|600||1х185 and above|
Larger and more complex works require the use of welding transformers or inverters of high power. For current loads of 289 Amperes it is necessary to choose a cable with a cross section of 35 mm2, 350-362 Amperes – 50 mm2. Transformers capable of “issuing” 437 Amps require 70 mm2 of wires, 522 Amps – 95 mm2. Cables with a cross section of 120 mm2 are required for the correct operation of welding rectifiers with a current of up to 600 Amperes.
Improperly selected cable cross section leads to overheating of the cable.
Inside the metal core are thin wires, which can be from 30 to 1000. Their total cross section is selected by the power of the device and the current used. For example, a cable with a cross section of 1×6 mm ² is designed for a maximum load of 11 kW with a current of 80-100 Amperes. But you can never use the calculated values to the maximum. It is optimal to always divide them by 2. As a result, such a wire is suitable for a power supply with a power consumption of 5 kW. With increasing current (A), it is necessary to increase the cross section of the cable.
If you cook “two” (2 mm electrode thickness) at a current of 80 A, you can do with a thin cable 1×6 mm “. But this will not allow the use of the electrode “three” (3 mm electrode thickness). Therefore, the devices must be completed based on the possible maximum strength of the welding current. For a household inverter in the country, a minimum of 1×16 mm is enough. The workshop needs 1×25 or 1×50 mm². Working with a cable with a smaller cross section leads to its overheating and melting.
Pay attention to the cable insulation, it must be of sufficient thickness. For example, for a cable KG 1×16, the insulation thickness is at least 1.1-1.2 mm, taking into account the permissible deviations. The insulation is often made of rubber, in the hands of the cable should bend easily.
IMPORTANTLY! Another nuance is the loss of current in the welding wires if you decide to extend the cable. So how long can you use an extension cord to connect a welding machine. Calculation formula for welding wires.
Wire cut resistance:
R – Resistance.
L – Length in meters.
S – Wire cross section in mm².
P – Specific resistance of copper (equal to 0.017 Ohm multiplied by mm² and divided by meters)
The formula looks like this:
R = P x (L / S)
You take an extension cord 30 meters. Cable cross section 1.5 mm ². The welding cable is connected to your machine 7 meters and a cross section of 25 mm².
It turns out R = 0.0017 x (30×2 / 1.5) – 0.68 Ohms.
Let’s move on.
U = 0.68 Ohm multiplied by 45 (45 is the maximum current consumed, for example, the device is taken “Svarog ARC 250 R112”) and it turns out 30.6 V.
Thus, we see that if you use a 30-meter extension cord with a cross section of 1.5 mm², then your device reaches not 220 V from the socket, but 189.4 V. (220-30.6).
If you take an extension cord with a thicker section, such as 25 mm², the loss will be less and will be 18.4 V. This means that the device will reach 201.6 V. from your outlet (220-18.4).
No need to demand the impossible from the device, if you connect a very long extension cord, you must understand that there will be a loss of power of the device.
Let’s look at another example. As standard, almost all manufacturers use three-meter welding cables. People often connect very long welding cables to the devices.
R = 0.017 x (7×2 / 25) = 0.00952 Ohm.
We take a welding cable 7 meters long and multiply by 2 (the current goes back and forth, from this you need to multiply 7 meters by 2) then divide by the cross section, let the cross section be 25 mm². We obtain 0.00952 ohms.
And now another formula.
Take the welding current 210 A ² and multiply by 0.00952 Ohms. We get 420 watts. Thus, your device will lose 420 watts of power. The thicker the cross section of the welding cable, the less loss. For example, taking a 35 mm² welding cable, you will lose 300 watts of power.
If you use an extension cord, always unwind it completely. If the extension cord is assembled into a coil, the cooling conditions deteriorate, which can lead to ignition of the wires or their melting, as the current consumed by the welding machine is higher than the allowable current of the extension cord, as a rule.
Now summarizing all the above, we summarize:
– The larger the extension cord, the greater the loss.
– To avoid serious losses – use an extension cord with a thick cable cross-section.
– To avoid additional losses when extending the welding cable – use a cable with the thickest possible cross section.
Another frequently asked question. How much will be the loss in Amperes if you use a long welding cable? This is very difficult to calculate, because the properties of the welding source are determined in the I – V characteristics (volt-ampere characteristic). For this purpose it is necessary to connect the welding machine to the Ballast rheostat and to measure amperes at this or that length of a cable. But in words we can say that when using a good welding cable with the right cross section – the losses in Amperes will be invisible. For example, a cable up to 10 meters with a cable cross section of 25 mm² – you will not feel any losses.
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