Explanations for welding cable and extension cords.
Dear customers, in this article we will tell you what length of extension cord you can use to connect welding machine, what kind of extension cord it should be and we’ll give practical advice on this topic.
Wire section resistance:
R – Resistance.
L – Length in meters.
S – Wire cross-section in mm².
P – Resistivity copper (equal to 0.017 ohms multiplied by mm² and divided by meters)
The formula looks like this:
Example:
You take a 30 meter extension cord. Cable cross-section 1.5 mm². The welding cable connected to your machine is 7 meters and has a cross-section of 25 mm².
It turns out R = 0.0017 x (30x2/1.5) – 0.68 Ohm.
U = 0.68 Ohm multiplied by 45 (45 is the maximum current consumption, the Svarog ARC 250 R112 device is taken as an example) and we get 30.6 V.
Thus, we see that if you use a 30-meter extension cord with a cross-section of 1.5 mm², then not 220 V from the outlet reaches your device, but 189.4 V. (220-30.6).
If you take an extension cord with a thicker cross-section, for example 25 mm², then the loss will be less and will be 18.4 V. This means that 201.6 V will reach the device from your outlet (220-18.4).
There is no need to demand the impossible from the device; if you connect a very long extension cord, you must understand that there will be losses in the power of the device. If you plug the kettle into a socket in Moscow, and the kettle itself is in St. Petersburg, then it will never boil.
Let's look at another example. Almost all manufacturers use three-meter welding cables as standard. People often connect very long welding cables to machines.
Formula:
R = 0.017 x (7x2/25) = 0.00952 ohms.
We take a welding cable 7 meters long and multiply it by 2 (the current goes back and forth, so you need to multiply 7 meters by 2) then divide it by the cross-section, let the cross-section be 25 mm². We get 0.00952 Ohm.
And now the second formula.
Let's take a welding current of 210 A² and multiply by 0.00952 Ohm. We get 420 W. Thus, your device will lose 420 W in power. The thicker the cross-section of the welding cable, the lower the losses. For example, if you take a 35 mm² welding cable, you will lose 300 W of power.
Important!
If you use an extension cord, always unwind it completely. If the extension cord is assembled into a reel, then the cooling conditions worsen, which can lead to fire of the wires or their melting, since the current consumption of the welding machine is higher permissible current extension cord, usually.
Results:
The larger the extension cord, the greater the losses.
To avoid serious losses, use an extension cord with a thick cable section.
To avoid additional losses when extending the welding cable, use a cable with as thick a cross-section as possible.
Another frequently asked question from our customers. How much will the loss be in Amperes if you use a long welding cable? This is very difficult to calculate because the properties welding source are determined in the current-voltage characteristic (volt-ampere characteristic). To do this, you need to connect the welding machine to a ballast rheostat and measure Amperes at a given cable length. But in words we can say that when using a good welding cable with the correct 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.
There are two types of typical I-V characteristics of sources: bayonet and flat I-V characteristics. It is different on different devices and different manufacturers. We will try to conduct experiments with different devices and inform you about the results.
A welding inverter is a device that greatly facilitates the arc welding process. And all the welders who at least once used this equipment were able to verify this.
The use of welding inverters is becoming more and more popular every year. These devices allow you to weld quickly and efficiently. But when using them, it is very important to connect the device correctly so that welding takes place in the required modes and continuously.
For normal operation of welding inverters, it is very important to choose the optimal wires. Today there are different types wires that ensure maximum productivity of the device. Welding wires for the inverter are selected based on several indicators:
- wire length;
- wire cross-sectional area value;
- The voltage drop in the welding circuit should not exceed 2 W.
What is the wire for a welding inverter?
Welding wires for the inverter are a current conductor that is sufficiently flexible and has insulation. Typically such a cable is made from copper wires who have different diameter(0.18 - 0.2 mm) and intertwined with each other. The top bundle of these wires is covered with a special insulating layer. This wire is used to supply current from the inverter directly to the electrode holder to connect the device to electrical network, as well as for grounding.
Please note that the selection of welding wires for the inverter is made solely on the basis technical characteristics both the cable itself and the welding machine. The stability and durability of the inverter depends on this.
Brands of welding cables for inverters.
It is believed that the most popular cable among welders is the KG brand cable, namely a special welding flexible wire, which is used both for connecting the welding machine, and specifically the inverter, to the network, and for supplying current to the electrode holder.
Manufacturers of this brand of cable advise using it in power circuits AC with a voltage not higher than 600 V and a frequency within 40 Hz. Also this brand of cable can be used in circuits DC having a voltage of no more than 1000 W.
KG brand cables differ in permissible load current, which depends on the cross section. The table shows these ratios.
Today this type of wire is produced in different variations, which are intended for use in different climatic conditions. So, for example, for work in the far north, where the air temperature is winter period can reach -60°C, wire of the KG-HL brand is produced. The sheath of such a cable is made of cold-resistant rubber. For places with a tropical climate there is cable brand KG-T. Their sheath is resistant to mold, in addition, such a cable can be used at air temperatures up to +85 ° C.
In addition to the popular KG brand, welders also use KOG1 brand cables, which have a special flexible core. This cable is very convenient: it allows the welder to move and change the position of the electrode holder without unnecessary movements and effort.
There are also special brand wires - KGN, which can be used in areas with increased fire hazard. These cables have a special sheath that does not burn.
Operation and connection of welding wires.
- When connecting wires to your welding inverter, you should remember the following rules:
- The connection is made using soldered or pressed cable lugs.
- The wires can be connected by crimping. The main thing is not to forget about the isolation of the connection itself.
- The wire is connected to the power connectors of the device (+) and to the electrode holder in reverse polarity (-). The polarity can only be changed if the current parameters have been changed.
- During welding, welders should not pull the machine towards themselves using wires.
- The rated power of the cable must strictly correspond to the connected device.
Can welding cables be extended?
This issue causes a lot of controversy among welders. But still experienced craftsmen they prefer not to do this, explaining that welding wires for the inverter that are too long can negatively affect the performance of the device itself. Proponents of greater convenience when working with an inverter argue that the manufacturers’ instructions do not say anything about the possibility of extending welding wires, but “what is not prohibited is permitted.” This means you can make the welding wires longer and not carry the machine itself to the welding site, but enjoy greater freedom of action at a distance from the inverter.
In order to understand which of these opinions is more correct, it is necessary to recall one of the laws of physics - Ohm's law. The fact is that along the entire length of the cable there is a “leakage” of voltage, and therefore a decrease in current strength - and the longer the cable, the greater these losses. The operation of all inverter systems depends on the output voltage and the set current, and these values are measured at the terminals of the device, and not at the end of the welding wire. If there is insufficient current at the place where the welder is working, the characteristics of the arc change and it becomes much more difficult to control. In order to achieve the desired current strength at the end of the welding wire, it is necessary to set an increased current on the inverter itself - and this is fraught with failure of the delicate electronics of the device, and, as a consequence, expensive repairs or even replacement of the inverter. So it turns out that it is much more profitable to bring the inverter itself to the welder’s place of work than to risk its performance by extending welding wires.
When using a welding inverter, there are often cases when the standard power cable does not allow the use of the unit in the area where the parts to be welded are located. It is not always possible to move the structures being welded closer to the welding station.
In such situations, extension cables are used; in everyday life they are called carriers, by analogy with household devices. The difference between them lies not only in the power of the wires used. Carrying welding inverter, used to connect powerful consumers, differ significantly from household products, and the requirements for it are special.
Carrying a welding inverter in a technical sense is a section electrical circuit between the current source and the consumer. We consider a household electrical outlet to be the current source. The consumer is a welding inverter or other high-power electrical equipment. For a section of an incomplete chain, the usual Ohm's law applies, according to which it is easy to calculate all the necessary parameters.
The carrying length has the maximum effect on the wire cross-section when equal powers consumers.
Wire material. Preference should be given to a material with lower resistivity. Copper meets this condition.
The cable insulation does not affect the resistance, but under operating conditions it experiences mechanical stress and is susceptible to abrasion and fracture. You should choose a wire with a thicker insulation layer. It may be more expensive, but it will last longer, and it is more convenient to work with such a cable; it is less prone to breaking.
The cross-section of the carrying cable wire is selected in accordance with the welding currents used. Knowing the carrying length, voltage and load current, it is easy to calculate the required wire cross-section. Suffice it to recall the school physics curriculum, the electricity section.
When calculating, you should not forget about the voltage drop in the section of the circuit that represents the transfer. It may happen that a voltage drop will create an overload in the home network.
All calculations should be carried out with a 10% power reserve. This will prevent the carrying wire from heating up.
When using long carriers, you should not leave an extra section of wire wound into a coil. One thing to keep in mind is inductance. A reactance will arise in the improvised coil, which will affect total resistance devices.
Included with the welding inverter, you should keep carriers of different lengths. The difference in length should be 10 m or more.
You don't have to bother with short carriers. It is enough to select the required wire cross-section for the current to avoid overheating.
Often a length of 20-30 meters or more is required. , in theory, is a conductor with an active load component. Resistance to him, who remembers from school curriculum, is determined from the simple formula Rpr. = ρ × L / S, and electrical processes obey Ohm’s law. As a formula, you can use its version for an incomplete chain I=U/Rpr. because when using a network connection EMF source does not affect the result.
- ρ – resistivity of the conductor, depends on the material of the wire. From available materials smallest value has copper.
- L – conductor length. In this case, this is our extension cord.
- S – cross-sectional area of the wire. It is indicated on the label.
- U – network voltage 220V. But such a voltage is ideal; it is practically necessary to measure real value. The correct choice of extension cord depends on this.
- I – current at maximum load to the inverter.
The formula shows a direct dependence of resistance on the length of the conductor and inverse relationship from the cross-sectional area. And as the resistance increases, the voltage drop across the circuit section increases. That's all the wisdom. The extension cord for the welding inverter should not have a significant effect on the network voltage. The voltage drop across it should be minimal. In any case, the cross-sectional area of the cable should not be less than the cross-section of the wiring in the house. Do not try to use household carriers. Wire size for household appliances choose to the minimum, you can save a lot on expensive copper. From experience we can say that a wire cross-section of 2.5mm2 will ensure safety when welding current up to 170A, provided that the network wiring can withstand it. It is rare that anyone at home is able to work with such current.
I would like to warn lovers of convenience. Do not wrap the extension cord around a reel. Do not forget about the occurrence of induction in ring conductors. If the resulting inductive reactance does not affect the operation of the inverter, then an increase in temperature in the coil, due to additional inductance, can melt the insulation on the wire. If you decide to wind, then do not wind tightly, it will reduce natural ventilation, and therefore worsen the cooling mode.
You should not be afraid of heating the extension cord wires. Normal temperature for wires it is considered 70°C, at this temperature the hand burns, so if the hand can withstand it, the extension cord will not overheat. But if the inverter turns off, then the supplied voltage is too low and the cause should be looked for. It does not necessarily relate to portability; rather, the problem is the low voltage of the supply network.
Explanation of welding cable and extension cords.
Dear customers, in this article we will tell you how long an extension cord can be used to connect a welding machine, what kind of extension cord it should be, and give practical advice on this topic.
Wire section resistance:
R – Resistance.
L – Length in meters.
S – Wire cross-section in mm².
P – Copper resistivity (equal to 0.017 Ohm times mm² and divided by meters)
The formula looks like this:
Example:
You take a 30 meter extension cord. Cable cross-section 1.5 mm². The welding cable connected to your machine is 7 meters and has a cross-section of 25 mm².
It turns out R = 0.0017 x (30x2/1.5) – 0.68 Ohm.
U = 0.68 Ohm multiplied by 45 (45 is the maximum current consumption, the Svarog ARC 250 R112 device is taken as an example) and we get 30.6 V.
Thus, we see that if you use a 30-meter extension cord with a cross-section of 1.5 mm², then not 220 V from the outlet reaches your device, but 189.4 V. (220-30.6).
If you take an extension cord with a thicker cross-section, for example 25 mm², then the loss will be less and will be 18.4 V. This means that 201.6 V will reach the device from your outlet (220-18.4).
There is no need to demand the impossible from the device; if you connect a very long extension cord, you must understand that there will be losses in the power of the device. If you plug the kettle into a socket in Moscow, and the kettle itself is in St. Petersburg, then it will never boil.
Let's look at another example. Almost all manufacturers use three-meter welding cables as standard. People often connect very long welding cables to machines.
Formula:
R = 0.017 x (7x2/25) = 0.00952 ohms.
We take a welding cable 7 meters long and multiply it by 2 (the current goes back and forth, so you need to multiply 7 meters by 2) then divide it by the cross-section, let the cross-section be 25 mm². We get 0.00952 Ohm.
And now the second formula.
Let's take 210 A² and multiply by 0.00952 Ohm. We get 420 W. Thus, your device will lose 420 W in power. The thicker the cross-section of the welding cable, the lower the losses. For example, if you take a 35 mm² welding cable, you will lose 300 W of power.
Important!
If you use an extension cord, always unwind it completely. If the extension cord is assembled into a reel, then the cooling conditions worsen, which can lead to fire of the wires or their melting, since the current consumption of the welding machine is higher than the permissible current of the extension cord, as a rule.
Results:
The larger the extension cord, the greater the losses.
To avoid serious losses, use an extension cord with a thick cable section.
To avoid additional losses when extending the welding cable, use a cable with as thick a cross-section as possible.
Another frequently asked question from our customers. How much will the loss be in Amperes if you use a long welding cable? This is very difficult to calculate, since the properties are defined in terms of the current-voltage characteristic. To do this, you need to connect the welding machine to a ballast rheostat and measure Amperes at a given cable length. But in words we can say that when using a good welding cable with the correct 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.
There are two types of typical I-V characteristics of sources: bayonet and flat I-V characteristics. It is different on different devices and different manufacturers. We will try to conduct experiments with different devices and inform you about the results.
Power extension cord for welding machine and inverter on a 30 meter reel.
Extension cord on a reel of 30 meters for a welding machine and inverter. The extension cord's wire cross-section is 3x2.5, allowing the extension cord to be used on a Umelets series reel with almost any welding machine or inverter. A powerful extension cord can withstand loads of up to 5,000 Watts at a current of 16 Amps. Household welding machines (both transformers and inverters) have approximate power 3.0-5.0KW. The power extension cord on the reel is used at temperatures of +1-+40 degrees Celsius. To work at low temperatures, you should buy an extension cord on a metal reel with a KG wire.
Additional information
| Weight | 2.5 |
|---|---|
| Size | 30 x 40 x 35 |
Product passport
Power extension cord type UХз 16-004 on a reel
Technical data
The extension cord is designed to connect household electrical appliances power up to 3500 W
electrical network voltage 220 V 50 Hz. The extension cord is operated and stored at ambient temperatures from 1 to 40°C and relative humidity up to 80%.
The product is certified.
Certificate No. TS RU C-U.ME64.В.00275
Safety and fire safety requirements. Do not use the extension cord in fire hazardous, chemically active or
humid environments, as well as subject to mechanical and thermal influences leading to destruction of the product.
Certificate of acceptance and sale
Extension cord brand UHZ 16-004 on a reel
Release date_____________________
Date of sale_____________________
Warranty
The manufacturer guarantees normal work extension cord within 1 year from the date of sale
subject to compliance with the rules of operation and storage.
The service life of the extension cord is 6 years.
Welding equipment is widely used at home, for which special devices are created that meet the requirements for comfortable home use. The professional field of application also has its own models, and almost always specialists may encounter such a problem as a lack of wire length for work. This situation can be encountered both at home and at work. If with a compact inverter for home you can still go to another place and move it, then with professional equipment This cannot always be done. An extension cord for a welding inverter helps solve this problem. Welding machines have sufficient high power, so switching elements are needed to connect and operate them. These elements will be able to withstand the specified operating parameters. Ordinary ones are not always suitable household networks and extension cords from them.
Classification
There are two main varieties, which differ in both appearance, and according to the characteristics of the destination. In any case, they serve to conduct current. The first extension cord for a welding machine is an ordinary network connection device that helps increase the distance from a stationary power source. The second type of extension cord allows you to increase the size of the wire for the welding machine, which is responsible for conducting the output voltage current, which is obtained after processing by the transformer. This is especially true if the apparatus itself is located permanently at the post, and it is necessary to carry out welding further than is provided for by the dimensions of the post.
Specifications
Each extension cord for a welding inverter can have its own unique characteristics, which depend on the scope of application and are manifested in the form of core diameters, length itself, pin features, and so on.
Calculation example for selecting an extension cord
When calculating which extension cord is needed for a welding inverter, you should understand that, first of all, it is a conductor of an active load, which becomes higher with increasing power.
The resistance of the extension cord can be determined by the following formula R=ρ×L/S. All electrical processes taking place in the system are subject to the basic laws of electrical engineering, in particular Ohm’s law I=U/R. Here the law is taken for a section of the circuit, since even after connecting the electromotive force, it does not affect the result. The symbols in the above formulas mean the following:
- I – maximum current at maximum high load inverter;
- U is the voltage that is obtained from the network, and the real one is taken, not the nominal one, which can differ markedly from the standard 220 V;
- S is the cross-sectional area of the cable, which can be found on the marking if there is a ready-made option;
- L – extension length;
- ρ is the specific resistance, which depends on the metal of the cores from which the extension cord is made.
According to the above formula, you can easily see the relationship between the length of the conductor, which is the extension cord here, and the resistance. There is also an inverse relationship between resistance and cross-sectional area. The higher the resistance of the extension cord, the more the voltage across the welding machine will drop.
To correctly calculate what kind of extension cord you need using the above formula, you should decide what amperage you mainly use. Many, as well as foreign analogues, operate normally at 170 A, although they have a large margin of maximum current. Based on this, we can accept the standard position for such parameters for the wire cross-section of 2.5 mm square, which should be obtained according to optimal calculations for such parameters.
Features of choice
The welding leads for the inverter and extension cord should not have a noticeable effect on the supplied voltage from the mains, but should be of adequate thickness to withstand the loads. Thus, everything should be reduced to ensuring that, with a minimum voltage drop, the core has maximum resistance to high power. If you have to determine everything by eye and no precision instruments to measure, it is worth selecting an extension cord of such a cross-section that would be no less than the thickness of the core in the room.
It’s safest to use purchased extension cords that have high-quality insulation.”
With ready-made cables, it is easier to choose what wire cross-section is needed for a welding machine, since they are immediately made according to optimal standards for certain types of equipment.
Proper use of an extension cord
Sometimes, the very advantages for which this device is created can become disadvantages. First of all, you need to pay attention to the fact that the extension cord must be used in a straightened state. Whatever cable you use for the welding inverter extension, it should be positioned so that it does not get twisted. For this reason, it is necessary to choose the length optimally, since otherwise, if everything is wound on a coil or other device, induction may occur that forms in the ring conductors. The resulting inductive reactance may not have any effect on the operation of the inverter, but there remains a risk of the temperature rising to such a level that the insulation on the wires begins to melt. It is not recommended to do full winding, as it reduces the level natural ventilation, and an increase in temperature leads to an increase in resistance.
The average temperature that extension cords can withstand is 70 degrees Celsius. Thus, one can easily determine permissible temperature, because if your hand can withstand the hot wire, then this is quite normal. If there are large overloads caused by the resistance of the extension cord, the inverter may turn off.
Typically, the length of the welding cable for an inverter welding machine is short - less than two meters. It can be not very convenient to work with such a cable, especially at heights. Most manufacturers do not recommend extending the cable.
What is this connected with? The fact is that during the break welding arc the current sharply drops to zero, and the output voltage, on the contrary, increases abruptly due to self-induction emf. This sudden increase in voltage can break through the output diodes.
Originally in inverter devices used to combat this phenomenon output choke. The task of the choke is to accumulate energy and then immediately release it to form a welding arc, at the moment when the key transistors are closed and no current flows through the primary winding. But in lately most manufacturers (even the most famous brands), in order to save money and reduce production costs, they exclude the output choke from the design of their devices. Its role is played by welding cables due to their inductance.
At first glance, it seems that nothing prevents in such a situation from increasing the cable length to any the right size. However, not everything is so simple. The cable has both active and reactive resistance, so there is a drop in the output voltage (and, accordingly, the current flowing through the cable) from the inverter output to the weld pool.
An inverter is a rather complex device; it includes such systems as:
- fast arc ignition,
- protection against sticking of the electrode to the part being welded,
- device for current stabilization at a given value.
This is how these systems work on the principle feedback, that is, the magnitude of the output voltage and current is of key importance. Moreover, it is on the output terminals of the device, and not on the electrode holder. Therefore, a change in the length of the cable and the associated change in its reactance and inductance can disrupt the operation of the entire system, up to the failure of the welding machine.
» Welding cable for inverter
The market for the production and sale of welding equipment offers wide range equipment of rectifier, transformer and inverter type. It is the latter type that is most widespread.
Inverters are easy to use, compact, mobile, easy to connect, and have affordable price, suitable for beginners and experienced professionals. Popularity of this equipment requires the right choice cable for it. The article will discuss which cable is best to use for an inverter welding machine.
Welding cable design
To ensure normal functioning The inverter should use wires with a copper base. Copper is the best conductor electric current. You should also use cords that have high flexibility. They simplify the work process and guarantee freedom of action for the performer.
Cable design includes the following elements:
- conductive copper wire round shape consists of many wires, the cross-section of which does not exceed 0.2 mm;
- coating the wires can be made of rubber or rubber (natural or butadiene);
- separation layer made of a special transparent film that prevents the coating and core from sticking together.
Characteristics of welding cables
As noted earlier, the cable for the inverter must have high flexibility. Besides this important property, electrical conductors are required to comply with the following characteristics:
- Strength, i.e. resistance to mechanical impact: shocks and tears.
- Resistance to temperature fluctuations, the ability to use the conductor in conditions of very low or fairly high temperatures.
- Resistance to sun rays and moisture.
- Immunity to mold and mildew.
- Elasticity- minimal likelihood of bending.
Welding cable for inverter: types
There are few brands of conductors designed specifically for welding work. And there are only two types of cables that meet the above characteristics: CG and COG.
Among craftsmen, the first type is in particular demand - . It should be used to connect mobile mechanisms to networks with alternating voltage up to 660 V with a frequency of 400 Hz. Also allowed constant voltage up to 1000 V.
Consequently, each performer will be able to independently answer the question posed in the title.