An inductor is the industrial name for an electrical element such as an inductor. This device has a wide range of applications, in particular, a powerful choke can be used to improve the performance of a semiautomatic device or an inverter for welding.

The main property of an inductor, which is a magnetic circuit wound under certain conditions around a ferromagnetic core, is the stabilization of the current strength over time.

Simply put, the voltage applied to the coil causes the output current to rise smoothly. The change in polarity leads to the same smooth decrease in the current strength.

The main factor is the condition that the current passing through the inductor cannot rise or fall sharply. This is what determines the value of using a choke for welding - resistance compensation avoids sharp jumps for amperage.

This allows you to insure against accidental burning of the workpieces being welded, to reduce the spatter of the consumable metal and to accurately select the current parameters for welding for a given metal thickness. The chances of getting a good weld with a choke weld are much higher.

The parameter that determines the coefficient of change in current is inductance. It is measured in H (henry) - in 1 second at a voltage of 1 V, only 1 A can pass through a choke with an inductance of 1 H.

The number of turns on a coil directly affects the magnitude of the inductance. It is directly proportional to the number of turns squared. But if you need to make a welding choke with your own hands, then it is not necessary to calculate the exact number of turns.

Since the parameters of the welding machines household use for the most part, they are standard and well-known, for the welder to make a choke with his own hand, it will be enough to use the instructions below.

The purpose

In an inverter for welding, a choke is needed to create an electric arc on the electrode. Ignition occurs when a certain voltage level is reached.

The welding choke increases the resistance, which shifts the phases between current and voltage and allows a smoother ignition. By itself, this fact often avoids burning through the workpiece, especially if parts made of thin sheet metal are being welded.

A smooth change in the current strength allows you not to spoil the workpiece by a sharp supply of overstated power, to optimally set the arc temperature and, accordingly, prevent metal splashing while maintaining the required processing depth.

Another valuable property is partial protection from unstable voltage in the network.

The choke for the welding inverter greatly facilitates the ignition of the electrode, which should light up at a higher voltage than the inverter produces.

An example would be an MP-3 electrode, which must be set to 70 volts to ignite. An output choke for welding can make it a lot easier with this, which produces only 48 volts when idle.

This is due to the phenomenon of self-induction. The device induces an EMF (electromotive force), which causes air breakdown and flashing of the welding arc, as soon as the additive is brought a few millimeters from the metal surface.

The choke for welding is connected to the secondary winding of the transformer in the machine. It can be used in any type of apparatus - both home-made and factory-made, operating on any principle - inverter, with a step-down transformer, and the like.

Materials for making

A choke for retrofitting a semiautomatic device or an inverter can be assembled by hand using structural elements from old technology- tube TVs, street lamps old construction and other devices that have a transformer.

Structurally, it is a core made of a material that conducts a magnetic field, but does not conduct an electric current or is reliably insulated, and three layers of windings, separated by a dielectric.

As a basis for the core, either a special material is suitable - ferrite, which has these properties, or a yoke (horseshoe) from an old transformer. The winding device for welding is done with an aluminum or copper wire with a cross section of 20-40 mm.

If aluminum is used, the wire cross-section must be at least 36 mm, the copper wire may be thinner. An 8 mm flat copper bar is suitable.

The dimensions of the core should allow winding about 30 turns of a bus of a given section, taking into account the dielectric spacers. A core from the step-up transformer of the Soviet TV TSA 270-1 is recommended.

Sequencing

When necessary tools and the materials are prepared, you can start making a choke for welding. The algorithm of actions is as follows:

1. disassemble the transformer, clean the coils from traces of old windings;
2. to make gaskets from fiberglass, cardboard impregnated with bakelite varnish, or other suitable dielectrics, which in the future will play the role of an inductive (air) gap. They can simply be glued to the corresponding coil surfaces. The thickness of the spacer should be 0.8-1.0 mm;
3. wind a thick copper or aluminum wire on each coil. It is worth focusing on a round wire made of aluminum with a cross section of 36 mm or copper with a similar ohmic resistance. On each "horseshoe" 3 layers of 24 turns in each are applied;
4. Between the layers, lay a dielectric material - fiberglass, cardboard impregnated with bakelite varnish or other dielectric. The gaskets must be reliable, since a choke of this design is prone to self-breakdown between windings. If the resistance between the windings is lower than the air resistance between the electrode and the filler, then the breakdown will occur between the windings, and the welding device will be irreversibly damaged.

Winding must be done evenly, without overlaps, strictly in the same direction, so that the "bridge" between the coils is on one side of the future choke, and the input and output contacts on the other.

In case of an error, the jumper can also be installed obliquely. It is important that its installation turns coils with different winding directions into coils with the same direction in fact.

Switching on and checking

The choke for welding is connected to the system between the diode bridge and ground - a contact that goes to the connection with the material to be welded. The output of the diode bridge is connected to the input of the choke, to the output of the assembled inductor, respectively, the ground contact.

The entire assembly for welding must be tested on a piece of metal of the same chemical composition and the thickness with which it is planned to carry out most of the welding work in the future. Quality indicators are:

• light electric ignition;
• arc stability;
• relatively weak crackling;
• smooth combustion without strong splashes of the melt.

Please note that the introduction of this element into the design welding machine leads not only to stabilization of work, but also to a certain drop in current strength. If the inverter or semiautomatic device starts to cook worse, it means that the current has dropped.

Disconnect the choke and remove a few turns from each coil. The exact number of turns in each case is selected empirically.

Technical data of our semiautomatic welding machine:
Supply voltage: 220 V
Power consumption: no more than 3 kVA
Operating mode: intermittent
Operating voltage regulation: stepwise from 19 V to 26 V
Welding wire feed speed: 0-7 m / min
Wire diameter: 0.8mm
The magnitude welding current: ED 40% - 160 A, ED 100% - 80 A
Regulation limit of welding current: 30 A - 160 A

A total of six such devices have been made since 2003. The device shown below in the photo has been working since 2003 in a car service and has never been repaired.

External view of the semiautomatic welding machine

Generally

Front view

Back view

Left view

The filler wire is a standard
5kg spool of wire diameter 0.8mm

Welding torch 180 A with Euro plug
was purchased from a welding equipment store.

Welder diagram and details

Due to the fact that the semiautomatic device circuit was analyzed from such devices as PDG-125, PDG-160, PDG-201 and MIG-180, circuit diagram differs from the circuit board, since the circuit was drawn on the fly during the assembly process. So it's best to stick with wiring diagram... On printed circuit board all points and details are marked (open in Sprint and hover the mouse).

Installation view

Control board

A 16A single-phase AE type circuit breaker was used as a power and protection switch. SA1 - switch for welding modes, type PKU-3-12-2037 for 5 positions.

Resistors R3, R4 - PEV-25, but you don't have to put them (I don't have them). They are designed to quickly discharge the inductor capacitors.

Now on the capacitor C7. Paired with a choke, it stabilizes combustion and maintains the arc. Its minimum capacity should be at least 20,000 microfarads, the optimal one is 30,000 microfarads. We tried several types of capacitors with smaller dimensions and larger capacities, for example CapXon, Misuda, but they did not show themselves reliably, they burned out.

As a result, Soviet capacitors were used, which work to this day, K50-18 at 10,000 microfarads x 50V in an amount of three pieces in parallel.

Power thyristors for 200A are taken with a good margin. You can put it on 160 A, but they will work at the limit, you will need to use good radiators and fans. The applied B200s stand on a small aluminum plate.

Relay K1, type RP21 for 24V, variable wire resistor R10, type PPB.

When the SB1 button is pressed on the torch, voltage is applied to the control circuit. Relay K1 is activated, thereby supplying voltage through the contacts K1-1 to solenoid valve EM1 for acid supply, and K1-2 - to the power supply circuit of the wire pulling motor, and K1-3 - to open the power thyristors.

The SA1 switch sets the operating voltage in the range from 19 to 26 Volts (taking into account the addition of 3 turns per arm up to 30 Volts). Resistor R10 regulates the feed of the welding wire, changes the welding current from 30A to 160 A.

When tuning, the resistor R12 is selected in such a way that when R10 is unscrewed at the minimum speed, the motor still continues to rotate, and does not stand.

When the SB1 button on the torch is released, the relay releases, the motor stops and the thyristors close, the electromagnetic valve, due to the charge of the capacitor C2, still remains open, supplying acid to the welding zone.

When the thyristors are closed, the arc voltage disappears, but due to the choke and capacitors C7, the voltage is removed smoothly, preventing the welding wire from sticking in the welding zone.

We wind the welding transformer

We take the OSM-1 transformer (1kW), disassemble it, put the iron aside, having previously marked it. We make a new coil frame from PCB 2 mm thick (the native frame is too weak). Cheek size 147 × 106mm. The size of the rest of the parts: 2 pcs. 130 × 70mm and 2 pcs. 87 × 89mm. In the cheeks we cut out a window measuring 87 × 51.5 mm.
The coil frame is ready.
We are looking for a winding wire with a diameter of 1.8 mm, preferably in reinforced fiberglass insulation. I took such a wire from the stator coils of a diesel generator). You can also use ordinary enamel wire such as PETV, PEV, etc.

Fiberglass is, in my opinion, the most better insulation it turns out

We start winding - the primary. The primary contains 164 + 15 + 15 + 15 + 15 turns. We make thin fiberglass insulation between the layers. Lay the wire as tightly as possible, otherwise it will not fit, but I usually had no problems with this. I took fiberglass from the remains of the same diesel generator. Everything, the primary is ready.

We continue to wind - the secondary housing. We take an aluminum bus in glass insulation measuring 2.8 × 4.75 mm (you can buy it from the wrappers). You need about 8 m, but it is better to have a small margin. We begin to wind, laying as tightly as possible, wind 19 turns, then we make a loop for the M6 ​​bolt, and again 19 turns, Beginnings and ends are made 30 cm each, for further installation.
Here is a small digression, for me personally, for welding large parts at such a voltage, the current was not enough, during operation I rewound the secondary winding, adding 3 turns per shoulder, in total I got 22 + 22.
The winding fits right next to it, so if you wind it carefully, everything should work out.
If you take an enamel wire for the primary, then impregnation with varnish is necessary, I kept the coil in varnish for 6 hours.

We assemble the transformer, plug it into the outlet and measure the no-load current of about 0.5 A, the voltage on the secondary from 19 to 26 Volts. If everything is so, then the transformer can be put aside, we no longer need it for now.

Instead of OSM-1 for a power transformer, you can take 4 pieces of TC-270, although there are slightly different sizes, and I made only 1 welding machine on it, then I don't remember the data for winding, but it can be calculated.

Let's wind the choke

We take an OSM-0.4 transformer (400W), we take an enamel wire with a diameter of at least 1.5 mm (I have 1.8). We wind 2 layers with insulation between the layers, put it tightly. Next, we take an aluminum rail 2.8 × 4.75 mm. and we wind 24 turns, we make the free ends of the bus 30 cm each. We assemble the core with a gap of 1 mm (lay pieces of PCB).
The choke can also be wound on iron from a color tube TV type TS-270. Only one coil is placed on it.

We still have one more transformer for powering the control circuit (I took a ready-made one). It should deliver 24 volts at about 6A.

Housing and mechanics

With the trances sorted out, we proceed to the body. The drawings do not show 20 mm flanges. We weld the corners, all iron is 1.5 mm. The base of the mechanism is made of stainless steel.

Motor M is used from a VAZ-2101 wiper.
The end switch for the return to the extreme position is removed.

To create a braking force, a spring is used in the reel, the first one that came to hand. The braking effect is increased by compressing the spring (i.e. tightening the nut).

Welding constant electric shock received widespread use not only on the scale of large industries, but also in home workshops. Modern market offers dozens (if not hundreds) of machines for electric welding, ranging from compact low-power welders to industrial high-performance units. Regardless of the type of equipment used for, they all have one problem in common - an uncontrolled voltage drop, which makes it difficult to ignite the arc and form a seam.

To solve this problem, craftsmen came up with a choke, introduced into a chain with welding equipment. Novice welders will immediately have many questions: “What is this part and how does it function? How to make a choke on your own device? How to calculate the throttle correctly? " In this article we will try to answer these and many other questions.

What is a choke for? This small part connected to the circuit ensures smooth ignition of the arc and maintains its stability even with voltage drops, besides, the metal practically does not spray, it turns out to be of better quality, you can fine-tune the apparatus and cook without problems.

The principle of operation is simple: the choke passes current through itself, accumulating it from the welding machine. The accumulated current is just used to compensate for the lost voltage. Also, the bias choke provides the desired current resistance if the voltage is too high.

It is not at all necessary to buy a throttle in a store, especially since it is far from a cheap purchase. This unit is quite possible to make yourself. Its design consists of a core and two windings with a cross section designed to work with a certain DC current value. That is why it will not be possible to make a universal choke, because a small part cannot cope with a powerful welder, and vice versa. So it is important to correctly calculate how much winding is needed to work with this or that voltage.

Current regulation

Welding current control is extremely important for correct work and the formation of quality. It can be done in several ways:

• Adjusting the current by changing the distance between the elements The most popular way. To reduce the amperage, move apart the cut transformer core. The induction will dissipate somewhat, and the current will be less. The larger the welding unit, the more the ability to adjust the current, because the adjustment interval directly depends on available size in the body of the device.
• Regulation of the current on the transformer winding. In this way, you can cut off part of the coil, thereby increasing the voltage value, letting the current flow along a shorter path. To weaken the current, the path must, on the contrary, be increased.
• Current regulation by means of a steel spring with clamping of terminals at a predetermined interval. This is a good way of adjusting, it allows you to smoothly adjust the current, but there is one significant drawback - the spring heats up a lot and at the same time is constantly under the feet of the master, and this is a gross violation.

If you introduce a choke into the circuit, then most of the problems associated with current regulation will be solved. At first glance, this small device is capable of fully compensating for the missing voltage or, on the contrary, playing the role of resistance if there is too much voltage. The choke current is adjusted very smoothly and the welder does not need to keep a hot spring under his feet.

Choke application

Do-it-yourself choke works best on welding transformers... Our practice proves this. The choke quickly ignites the arc even with a significant loss of current, so it can be used without problems in the country or in a workshop with an unstable voltage.

A separate feature is the ability to use a choke in tandem with a rectifier. A choke + rectifier combination is capable of increasing the electromotive force of self-induction. In the case of a semiautomatic device, such a set of equipment will make it easy to ignite the arc even at a considerable distance from the metal surface.

DIY choke

Now let's figure out how a do-it-yourself welding choke can be wound and how to calculate the choke. To wind the choke correctly, you need to thoroughly know its structure and understand the principle of operation. In chapter " general information»We have briefly described the device and the principle of operation of this device. We have compiled a small step-by-step instructions, following which you can collect the choke. The part you assembled will be suitable for use on small production or for home welding. So let's get started:

1. First you need to find an old transformer, it will be our base. Experienced craftsmen it is advised to take a step-up element from a tube TV model "TCA 270-1", it will act as a core. Similar models can be easily found at a flea market or searched on the Internet on online message boards.
2. Then you need to disassemble the transformer. This is done simply: you need to cut off the bolts or turn the heads at the top of the unit, then remove the coils.
3. The resulting "horseshoes" (as the craftsmen call them) are installed with special gaskets. They are made of thin cardboard and glued to the base of the "horseshoe". Spacers are needed to form an inductive gap.
4. Now you need to wind the wire around the "horseshoe". To do this, we take aluminum wires with a cross section of 36 millimeters. Wind 22-24 turns on each side. If you managed to find a core from a tube TV, then you can wind 8 turns on each side in two layers. Don't forget to insulate with paper and bakelite varnish between the threads.
5. The wire should be wound in one direction on each of the spools. This is necessary so that at the end of the wire they are located in the same direction and at the top there is a jumper between the taps connecting the coils, and at the bottom there is the input and output.
6. If you nevertheless wound the wires incorrectly, and they are located in different direction, then install a diagonal oblique jumper between the upper and lower taps. The second pair of bends will act as an inlet and outlet.
7. It is recommended to install a choke in the welding machine only after the diodes. Connect the diode bridge cable to the input.

If the current strength of the choke, on the contrary, continues to fall during application, then you need to remove several turns on each of the coils.

The purchase of a welding machine (inverter) is always associated with a dilemma: quality or price. And, as often happens, price wins. By purchasing an inexpensive welding inverter, its owner receives a slight decrease in the quality of work with the unit. Or rather: the difficulty with the ignition of the electrode and the rigidity of the welding process. But a small modification (and inexpensive) makes it possible to change the characteristics of the device. The easiest option is to install a choke. What is it and what is a choke for?

Its main purpose is to stabilize the current. The thing is that the apparatus alternating current the ignition of the consumable must be carried out at a certain voltage, which must correspond to the sinusoid of the electric current. A welding choke included in the inverter circuit allows phase shifting between voltage and electric current. And this, in turn, affects the ease of ignition of the electrode, plus more even combustion electric arc... In the compartment, the end result is a smooth and high-quality weld seam. This is what is required to confirm the quality of the final result.

Chokes can be installed in welding transformers, and in inverters, and in semiautomatic devices. When using the device in semiautomatic devices for welding, one can state a decrease in metal spatter, the seam is boiled deeper, the welding process is softer.

Methods for adjusting the current using a choke

The advantages of the device are undeniable. Practice fully confirms this. But there are three modes of the transformer in which it can be. At the same time, with the help of a choke in some of them, you can adjust the strength of the welding current. By the way, the choke is connected to the secondary winding of the transformer, while the air gap in the core is regulated.

1. Idling. This is the mode when the device is turned on, but no work is performed on it. The voltage is applied to the transformer, the electromotive force is present in the secondary winding, but there is no welding current at the output of the welding current.
2. Load. An arc is ignited and completes the electrical input circuit. It includes the choke winding and the secondary winding of the transformer. A current moves along the circuit, the value of which is determined by the resistances of the two windings. If a choke was not installed in the circuit, then the output would have a maximum current. And this is a high probability of getting a burn-through of the metals being welded, sticking of the electrode. The degree of current adjustment will depend on the air gap in the rod around which the choke winding is wound.
3. Short circuit. A short circuit is formed at the moment when the tip of the electrode touches the metal workpieces to be welded. In this case, an alternating magnetic flux is formed on the transformer core, and an electromotive force is induced on the secondary winding. In this case, the current strength will depend on the total resistance of the inductor winding and the secondary winding of the transformer.

As for the air gap, an increase in it leads to the fact that the resistance of the chain increases. And this, in turn, leads to a decrease in the magnetic flux, respectively, the inductive resistance of the transformer and choke windings decreases. The resistance decreased, the output current increased. Everything is according to Ohm's law. Therefore, the arc current increases. In this way, with the help of a choke, you can adjust the current of the welding arc.

This choke system has one drawback. Any welding machine vibrates during operation. This negatively affects the flow of current through the inductor coil. Therefore, you can abandon the continuous adjustment and current regulation, and go to the step setting. For this, an air gap does not need to be set in the choke core. For this, the winding of the device is made with taps (after a certain number of turns), to which the contacts are soldered. True, it is necessary to take into account the moment that a current of several hundred amperes will pass through these contacts. Therefore, you need to choose those that can withstand such a current.

And one more reason why the choke for the welding machine must be turned on so that the welding process takes place in "soft" conditions. There is such a characteristic of the dependence of the welding arc voltage on the current strength at the end of the electrode, which is called falling. This is a very useful relationship, especially in cases where it is difficult or difficult to maintain the distance between the electrode and the metal workpieces being welded.

It is almost impossible to provide the falling characteristic with one transformer, because the resistance of its windings is not enough here. The inductor winding almost doubles the total resistance of the electrical circuit, which allows for a decreasing dependence of voltage on current. That is, this is another plus in the choke's piggy bank. Now it becomes clear why this device is needed.

How to make a choke with your own hands

For the choke coil, it is better to use the UI series magnetic core. Winding a wire onto a coil is a difficult and time-consuming process that requires patience and accuracy. There are several points in this business that determine the quality of the final result.

• It is imperative that the UI yoke is insulated before starting winding.
• Winding copper or aluminum wire only possible in one direction.
• Each layer wound on the core must be insulated from the next. What can be used for fiberglass, special cotton insulation or cardboard.
• The insulating layer must be treated with bakelite varnish.
• If a stepped current adjustment is arranged, then the winding leads must be marked. This will simplify the subsequent connection of the choke to the welding machine, that is, the desired output will be easy to find.

The stepwise current regulation can also be organized using a load ohmic resistance. In fact, this is an ordinary nichrome wire spiral that connects to the output of the choke. However, it should be noted that this option is not the best. Nichrome wire it gets very hot, sometimes even red hot, so this is a big danger.

In welding transformers, smooth current regulation is provided by displacement of the primary winding relative to the secondary. By decreasing the distance between them, a decrease is made magnetic field... And accordingly, a decrease in resistance in the circuit. Typically, transformer devices are equipped with a handle, which is located on top of the unit. Turning the knob in one direction or the other decreases or increases the arc current.

But for an inverter welding machine, which is used in everyday life, it is better to use a choke to improve performance. Easier, more convenient, inexpensive. Moreover, making it yourself is not a problem.

There are a lot of inexpensive semiautomatic welding machines on the market that will never work normally because they were originally made incorrectly. Let's try to fix this on a welding machine that has already fallen into disrepair.

Chinese fell into my hands semi-automatic welding Vita (hereinafter I will simply call it PA), in which the power transformer burned out, just friends asked to repair it.

They complained that when they were still working, it was impossible for them to cook something, strong splashes, crackling, etc. So I decided to confuse him, and at the same time share my experience, maybe someone will come in handy. At the first inspection, I realized that the transformer for the PA was not wound correctly, since the primary and secondary windings were wound separately, the photo shows that only the secondary remained, and the primary was wound nearby (this is how the transformer was brought to me).

This means that such a transformer has a steeply falling current-voltage characteristic (volt-ampere characteristic) and is suitable for arc welding but not for PA. For Pa, a transformer with a rigid I - V characteristic is needed, and for this, the secondary winding of the transformer must be wound over the primary winding.

In order to start rewinding the transformer, you need to carefully unwind the secondary winding without damaging the insulation, and cut the partition separating the two windings.

For the primary winding, I will use a copper enamel wire 2 mm thick, for a full rewind, 3.1 kg is enough for us copper wire, or 115 meters. We wind coil to coil from one side to the other and vice versa. We need to wind 234 turns - this is 7 layers, after winding we make a bend.

We insulate the primary winding and branches with cloth tape. Then we wind the secondary winding with the wire that we unrolled earlier. We wind 36 turns tightly, with a 20 mm2 shank, approximately 17 meters.

The transformer is ready, now we will deal with the choke. The throttle is an equally important part in the PA without which it will not work normally. It was done incorrectly, because it does not have a gap between the two parts of the magnetic circuit. I will wind the choke on the iron from the TS-270 transformer. We disassemble the transformer and take only the magnetic circuit from it. We wind the wire of the same section as on the secondary winding of the transformer by one roll of the magnetic circuit, or by two, connecting the ends in series, as you like. The most important thing in the choke is the non-magnetic gap, which should be between the two halves of the magnetic circuit, this is achieved by PCB inserts. The thickness of the strip ranges from 1.5 to 2 mm, and is determined experimentally for each case separately.