Thyristor e122 25 3 specifications. Electronic current regulator for welding transformer

Power thyristors Т122-25– pin powerful thyristors of general purpose. Convert and regulate direct and alternating current up to 25A frequency up to 500 Hz in voltage circuits 100V - 1600V(1-16 cells). Case type of thyristors of the T122-25 series - ST2: thread - M6, weight - 11 g. "ST" stands for "stud thyristor" - pin thyristor.

Pin assignment(pinout): thyristor base - anode, hard long output - cathode, hard short output - control electrode.

Are made for operation in moderate, cold (UHL) or tropical (T) climate; accommodation category - 2.

To remove heat, thyristors are assembled with coolers using a threaded connection. To ensure reliable thermal and electrical contact with the cooler during assembly, the torque M d for T122-25 thyristors must be 1.4-1.8 Nm. It is also recommended to use heat-conducting paste KPT-8.

Thyristors T122-25 are used in power supply circuits for electrical installations of direct and alternating current and in semiconductor power converters.

Specifications, decoding of marking symbols, dimensions, used coolers are listed below. The guarantee of operation of the thyristors supplied by our company is 2 years from the date of their purchase. Quality documents are provided.

The final price for T122-25 thyristors depends on the class, quantity, delivery time and form of payment.

Detailed characteristics of thyristors T122-25:

Deciphering the marking of thyristors T122-25:

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The most optimal method is the stepwise adjustment of the current, by changing the number of turns, for example, by connecting to the taps made when winding the secondary winding of the transformer. However, this method does not allow wide adjustment of the current, so it is usually used to adjust the current. Among other things, adjusting the current in the secondary circuit of the welding transformer is associated with certain problems. In this case, significant currents pass through the control device, which is the reason for the increase in its dimensions. For the secondary circuit, it is practically impossible to find powerful standard switches that would withstand currents up to 260 A.

If we compare the currents in the primary and secondary windings, it turns out that the current in the circuit of the primary winding is five times less than in the secondary winding. This suggests the idea of ​​placing the welding current regulator in the primary winding of the transformer, using thyristors for this purpose. On fig. 20 shows a diagram of the thyristor welding current controller. With the utmost simplicity and availability of the element base, this regulator is easy to manage and does not require configuration.

Rice. 1 Schematic diagram of the welding transformer current regulator:
VT1, VT2 -P416

VS1, VS2 - Е122-25-3

C1, C2 - 0.1 uF 400 V

R5, R6 - 1 kOhm

Power control occurs when the primary winding of the welding transformer is periodically switched off for a fixed period of time at each half-cycle of current. In this case, the average value of the current decreases. The main elements of the regulator (thyristors) are connected opposite and parallel to each other. They are alternately opened by current pulses generated by transistors VT1, VT2.

When the regulator is connected to the network, both thyristors are closed, capacitors C1 and C2 begin to charge through the variable resistor R7. As soon as the voltage on one of the capacitors reaches the avalanche breakdown voltage of the transistor, the latter opens, and the discharge current of the capacitor connected to it flows through it. Following the transistor, the corresponding thyristor opens, which connects the load to the network.

By changing the resistance of the resistor R7, you can control the moment the thyristors are turned on from the beginning to the end of the half-cycle, which in turn leads to a change in the total current in the primary winding of the welding transformer T1. To increase or decrease the adjustment range, you can change the resistance of the variable resistor R7 up or down, respectively.

Transistors VT1, VT2, operating in avalanche mode, and resistors R5, R6 included in their base circuits, can be replaced with dinistors (Fig. 2)

Rice. 2 Schematic diagram of replacing a transistor with a resistor with a dinistor, in the current regulator circuit of a welding transformer.
The anodes of the dinistors should be connected to the extreme terminals of the resistor R7, and the cathodes should be connected to the resistors R3 and R4. If the regulator is assembled on dinistors, then it is better to use devices such as KN102A.

As VT1, VT2, old-style transistors such as P416, GT308 have proven themselves well, however, these transistors, if desired, can be replaced with modern low-power high-frequency transistors with similar parameters. Variable resistor type SP-2, and fixed resistors type MLT. Capacitors of the MBM or K73-17 type for an operating voltage of at least 400 V.

The design of a convenient and reliable DC regulator is proposed. Its voltage range is from 0 to 0.86 U2, which allows this valuable device to be used for various purposes. For example, for charging high-capacity batteries, powering electric heating elements, and, most importantly, for welding with both a conventional electrode and stainless steel, with smooth current adjustment.

Schematic diagram of the DC regulator.

A graph explaining the operation of a power unit made according to a single-phase asymmetric bridge circuit (U2 is the voltage coming from the secondary winding of the welding transformer, alpha is the thyristor opening phase, t is time).

The regulator can be connected to any welding transformer with secondary winding voltage U2=50. 90V. The proposed design is very compact. The overall dimensions do not exceed the dimensions of a conventional unregulated bridge type rectifier; for DC welding.

The regulator circuit consists of two blocks: control A and power B. Moreover, the first is nothing more than a phase-pulse generator. It is made on the basis of an analogue of a unijunction transistor, assembled from two semiconductor devices of n-p-n and p-n-p types. With the help of a variable resistor R2, the direct current of the structure is regulated.

Depending on the position of the slider R2, the capacitor C1 is charged here up to 6.9 V at different rates. When this voltage is exceeded, the transistors open sharply. And C1 begins to discharge through them and the winding of the pulse transformer T1.

A thyristor, to the anode of which a positive half-wave approaches (the impulse is transmitted through the secondary windings), opens at the same time.

As a pulse, you can use industrial three-winding TI-3, TI-4, TI-5 with a transformation ratio of 1:1:1. And not only these types. For example, good results are obtained by using two two-winding transformers TI-1 with a series connection of the primary windings.

Moreover, all the named types of TI allow isolating the pulse generator from the control electrodes of thyristors.

There is only one “but9raquo;. The power of the pulses in the secondary windings of the TI is insufficient to turn on the corresponding thyristors in the second (see diagram), power block B. The way out of this “conflict9raquo; situation was found elementary. To turn on the powerful ones, low-power thyristors with high sensitivity to the control electrode were used.

The power unit B is made according to a single-phase asymmetric bridge circuit. That is, thyristors work here in one phase. And the shoulders on VD6 and VD7 during welding work like a buffer diode.

Mounting? It can also be mounted mounted, based directly on a pulse transformer and other relatively “large-sized”9raquo; schema elements. Moreover, the radio components connected to this design, as they say, are at least-minimorum.

The device starts working immediately, without any adjustments. Get yourself one - you won't regret it.

A. CHERNOV, Saratov. Model designer 1994 No. 9.

Category: "Electronic homemade products"

Simple electronic welding current controller, circuit

Often you have to weld metal of different thicknesses and use electrodes of different diameters, and in order for welding to be of high quality, it is necessary to adjust the welding current so that the seam lies evenly and the metal does not splatter. But, it is quite problematic to regulate the current of the secondary winding of the welding transformer, because. it can reach up to 180-250A.

As an option, nichrome spirals are used to adjust the welding current, including them in series in the circuit of the primary or secondary winding of the welding transformer, or inductors. It is inconvenient to regulate the current in this way, and the regulator itself is cumbersome. But there is another way out - to make an electronic welding current controller that would regulate the current in the primary winding of the welding machine.

The welding current regulator for a home-made welding machine is still very useful in cases where you have to weld metal in places where the power grid is weak, in villages for example. As a rule, they limit the current consumption for each house by setting the input machine to 16 A, i.e. it is impossible to turn on the load more than 3.5 kW. And a good welding machine, welding with electrodes with a diameter of 4-5 mm, consumes 6-7, or even 8 kW.

Therefore, we reduced the welding current and at the same time reduced the current consumption of the matcher, so we invested in those 3.5 kW and welded what you need with a “troika”.

Here is a simple circuit of such a regulator on 2 thyristors and it has a minimum of non-deficient parts. It can be done on 1 triac, but, as practice has shown, it is more reliable on thyristors.

The welding current regulator works as follows: a regulator is connected in series to the primary winding circuit, which consists of two controlled thyristors VS1 and VS2 (T122-25-3, or E122-25-3), for each half-wave. The opening moment of the thyristors is determined by the RC circuit (R7, C1, C2). By changing the resistance R7, we change the opening moment of the thyristors and thereby change the current in the primary winding of the transformer, and therefore the current in the secondary winding also changes.

Transistors can be used of the old type - P416, GT308, they can be easily found in old receivers or televisions, and capacitors are used of the MBT or MBM type for an operating voltage of at least 400 V.

Transistors VT1, VT2 and resistors R5, R6, connected as shown in the diagram, are an analogue of dinistors and in this embodiment they work better than dinistors, but with a strong desire, instead of VT1, R5 and VT2, R6, you can put ordinary dinistors - type KN102A.

When assembling and adjusting the welding current regulator, do not forget that the control takes place under a voltage of 220V. Therefore, in order to prevent electric shock, all radio elements, as well as thyristor heat sinks, must be isolated from the case!

In practice, the above electronic welding current regulator has proven itself well.
The material from the Radioamator magazine was taken as a basis. - 2000. - No. 5 “Do-it-yourself welding transformer”.

Recently I was talking with my teacher at the university, and, to my misfortune, revealed my amateur radio talents. In general, the conversation ended with the fact that I undertook to assemble a thyristor rectifier with a smooth current regulator for his welding “donut”. Why is this needed? The fact is that alternating voltage cannot be welded with special electrodes designed for constant, and given that welding electrodes come in different thicknesses (most often from 2 to 6 mm), then the current value must be proportionally changed.

When choosing a circuit for a welding regulator, I followed the advice of -igRomana- and settled on a fairly simple regulator, where the current is changed by applying pulses to the control electrodes, which are formed by an analogue of a powerful dinistor assembled on a KU201 thyristor and a KS156 zener diode. See the diagram below:

Despite the fact that an additional winding with a voltage of 30 V was required, I decided to make it easier, and in order not to touch the welding transformer itself, I installed a small additional 40 watt. Thus, the prefix-regulator has become completely autonomous - you can connect it to any welding transformer. The remaining parts of the current regulator were assembled on a small board made of foil textolite, the size of a pack of cigarettes.

As a base, I chose a piece of vinyl plastic, where I screwed the TS160 thyristors themselves with radiators. Since there were no powerful diodes at hand, two thyristors had to be forced to perform their function.

It is also attached to a common base. Terminals are used to input the 220 V network, the input voltage from the welding transformer is supplied to the thyristors through M12 screws. We remove the constant welding current from the same screws.

The welding machine is assembled, it's time for testing. We apply a change from the torus to the regulator and measure the output voltage - it almost does not change. And it shouldn’t, since at least a small load is needed to accurately control the voltage. It can be a simple 127 (or 220 V) incandescent lamp. Now, even without any testers, you can see a change in the brightness of the lamp filament, depending on the position of the resistor-regulator engine.

So it’s clear why the second tuning resistor is indicated according to the scheme - it limits the maximum value of the current that is supplied to the pulse shaper. Without it, the output already from half of the engine reaches the maximum possible value, which makes the adjustment not smooth enough.

To correctly adjust the current range, it is necessary to bring the main regulator to the maximum current (minimum resistance), and gradually reduce the resistance with the trimmer (100 Ohm), until its further decrease leads to an increase in welding current. Capture this moment.

Now the tests themselves, so to speak, for iron. As intended, the current is normally regulated from zero to maximum, however, the output is not constant, but rather a pulsed direct current. In short, the DC electrode did not cook, and does not cook as it should.

We'll have to add a block of capacitors. To do this, there were 5 pieces of excellent electrolytes at 2200 uF 100 V. Connecting them with two copper strips in parallel, I got just such a battery.

We are conducting tests again - the DC electrode seems to have begun to cook, but a bad defect was discovered: at the moment the electrode touches, a microexplosion and sticking occurs - this is the capacitors being discharged. Obviously, you can't do without a throttle.

And then luck did not leave us with the teacher - in the supply room there was just an excellent DR-1C choke, wound with a 2x4 mm copper bus on W-iron and having a weight of 16 kg.

Quite another matter! Now there is almost no sticking and the DC electrode cooks smoothly and efficiently. And at the moment of contact, there is not a microexplosion, but rather a slight hiss. In short, everyone is happy - the teacher is an excellent welding machine, and I am getting rid of stuffing my head with an archimute object that has nothing to do with electronics :)

How to make a simple current regulator for a welding transformer

An important design feature of any welding machine is the ability to adjust the operating current. In industrial devices, different methods of current regulation are used: shunting with the help of various types of chokes, changing the magnetic flux due to the mobility of the windings or magnetic shunting, the use of active ballast resistance stores and rheostats. The disadvantages of such an adjustment include the complexity of the design, the bulkiness of the resistances, their strong heating during operation, and inconvenience when switching.

The most optimal option is to make it with taps even when winding the secondary winding and, by switching the number of turns, change the current. However, this method can be used to adjust the current, but not to adjust it over a wide range. In addition, the regulation of the current in the secondary circuit of the welding transformer is associated with certain problems.

Thus, significant currents pass through the control device, which leads to its bulkiness, and for the secondary circuit it is practically impossible to select such powerful standard switches that they can withstand currents up to 200 A. Another thing is the primary winding circuit, where the currents are five times less.

After a long search through trial and error, the best solution to the problem was found - a well-known thyristor controller, the circuit of which is shown in Fig. 1.

With the utmost simplicity and availability of the element base, it is easy to manage, does not require settings and has proven itself in work - it works just like a “clock”.

Power control occurs when the primary winding of the welding transformer is periodically switched off for a fixed period of time at each half-cycle of current. In this case, the average value of the current decreases.

The main elements of the regulator (thyristors) are connected opposite and parallel to each other. They are alternately opened by current pulses generated by transistors VT1, VT2. When the regulator is connected to the network, both thyristors are closed, capacitors C1 and C2 begin to charge through the variable resistor R7. As soon as the voltage on one of the capacitors reaches the avalanche breakdown voltage of the transistor, the latter opens, and the discharge current of the capacitor connected to it flows through it.

Following the transistor, the corresponding thyristor opens, which connects the load to the network. After the beginning of the next, opposite in sign, half-cycle of the alternating current, the thyristor closes, and a new capacitor charging cycle begins, but in reverse polarity. Now the second transistor opens, and the second thyristor reconnects the load to the network.

By changing the resistance of the variable resistor R7, you can control the moment the thyristors are turned on from the beginning to the end of the half-cycle, which in turn leads to a change in the total current in the primary winding of the welding transformer T1. To increase or decrease the adjustment range, you can change the resistance of the variable resistor R7 up or down, respectively.

Transistors VT1, VT2, operating in avalanche mode, and resistors R5, R6 included in their base circuits, can be replaced with dinistors. The anodes of the dinistors should be connected to the extreme terminals of the resistor R7, and the cathodes should be connected to the resistors R3 and R4. If the regulator is assembled on dinistors, then it is better to use devices such as KN102A.

Variable resistor type SP-2, the rest type MLT. Capacitors of the MBM or MBT type for an operating voltage of at least 400 V.

A properly assembled regulator does not require adjustment. It is only necessary to make sure that the transistors are stable in the avalanche mode (or that the dinistors are turned on in a stable way).

Attention! The device has a galvanic connection to the network. All elements, including thyristor heat sinks, must be isolated from the case.

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Assembling homemade DC welding machines

• Welding machine: arc characteristic
• Dynamic response
• Possible details and calculations
• circuit diagram
• Welding scheme work:
• The design of the transformer and chokes
• Apparatus design
  • Details and materials of the welding device:
  • Assembly Tools

To make homemade DC welders, you will need a high power power source that converts the nominal voltage of a conventional single-phase network and provides a constant amount (in amps) of the appropriate current to directly start and hold a normal arc.

Schemes of a home-made apparatus for welding on direct current.

The power supply of increased power is a circuit of the following components:

• rectifier;
• inverters;
• current and voltage transformer;
• current and voltage regulators that improve the quality characteristics of the electric arc (thyristors, triacs);
• auxiliary devices.

In fact, based on homemade schemes, the transformer was and remains the source of the electric arc, even if auxiliary units and circuits of various control units are not used.

Homemade apparatus: block diagram

Schematic diagram of the power supply unit of the welding machine.

The power supply is inserted into a suitable plastic or metal box. It is supplied with the necessary elements: connectors, various switches, terminals and regulators. The welding machine can be equipped with carrying handles and wheels.

Such a design of fairly good quality welding can be done independently. The main secret of such a device is a minimal understanding of the welding process, the choice of material, as well as skill and patience in the manufacture of this device.

But to assemble the device yourself, you must at least understand a little and learn the basic skills, the moment of occurrence and burning of the electric arc and the theory of electrode melting. Know the characteristics of welding transformers and their magnetic circuits.

Back to index

Homemade device: transformer

The basis of any welding device circuit is a normal voltage step-down (from 220 V to 45-80 V) transformer. It works in a special arc mode with maximum power. Such transformers are simply obliged to withstand very high currents with a nominal value of about 200 A. Their characteristics must be consistent, the I-V characteristic of the transformer must necessarily fully comply with special requirements, otherwise it cannot be used for arc welding mode.

Welding machines (their designs) vary greatly. The variety of home-made welding transformers is huge, because there are a lot of truly unique solutions in the designs. In addition, home-made transformers are very simple: they do not have additional devices designed to directly adjust the current of the structure that flows:

The design of a homemade semi-automatic welding machine.

• with the help of highly specialized regulators;
• by switching a certain number of coil turns.

The transformer mainly consists of the following elements:

1. Metal magnetic circuit. It is carried out by a set of plates made of transformer steel.
2. Windings: primary (network) and secondary (working). They come with outputs for adjustment (by switching) or for the device circuit.

When calculating the transformer for the required current, welding is carried out, as a rule, immediately from the working winding, without hanging circuits and various elements of limitation and adjustment. Primary winding must be performed with terminals, taps. They serve to increase or decrease the current (for example, to adjust the transformer at low mains voltage).

The main part of any transformer is its magnetic core. In the manufacture of home-made developments, magnetic circuits are used from decommissioned stators of electric motors, old television and power transformers. Therefore, there is a huge variety of various magnetic circuits developed by craftsmen for such devices.

Welding transformer based on the widespread LATR2 (a).

• dimensions of the magnetic circuit;
• windings - the number of turns;
• voltage level at the input-output;
• I p - current consumed;
• I max - maximum output current.

Additional characteristics are simply impossible to evaluate or measure at home, even with the help of instruments. But just they determine the suitability of the transformer of the apparatus for the formation of a high-quality seam when powered in manual welding mode.

This directly depends on how the transformer "holds the current" and is called the external CVC (VAC) of the power supply.

ВВХ - the dependence of the potentials (U) on the connectors and the welding current, which varies from the load properties of the transformer and from the electric arc.

For hand welding, only a steeply falling characteristic is used, and in automatic machines, a gently dipping and rigid one is used.

Often you have to weld metal of different thicknesses and use electrodes of different diameters, and in order for welding to be of high quality, it is necessary to adjust the welding current so that the seam lies evenly and the metal does not splatter. But, it is quite problematic to regulate the current of the secondary winding of the welding transformer, because. it can reach up to 180-250A.

As an option, nichrome spirals are used to adjust the welding current, including them in series in the circuit of the primary or secondary winding of the welding transformer, or inductors. It is inconvenient to regulate the current in this way, and the regulator itself is cumbersome. But there is another way out - to make an electronic welding current regulator that would regulate the current in the primary winding of the welding machine.

The welding current regulator for a home-made welding machine is still very useful in cases where you have to weld metal in places where the power grid is weak, in villages for example. As a rule, they limit the current consumption for each house by setting the input machine to 16 A, i.e. it is impossible to turn on the load more than 3.5 kW. And a good welding machine, welding with electrodes with a diameter of 4-5 mm, consumes 6-7, or even 8 kW.

Therefore, we reduced the welding current and at the same time reduced the current consumption of the matcher, so we invested in those 3.5 kW and welded what you need with a "troika".

Here is a simple circuit of such a regulator on 2 thyristors and it has a minimum of non-deficient parts. It can be done on 1 triac, but, as practice has shown, it is more reliable on thyristors.

The welding current regulator works as follows: a regulator is connected in series to the primary winding circuit, which consists of two controlled thyristors VS1 and VS2 (T122-25-3, or E122-25-3), for each half-wave. The opening moment of the thyristors is determined by the RC circuit (R7, C1, C2). By changing the resistance R7, we change the opening moment of the thyristors and thereby change the current in the primary winding of the transformer, and therefore the current in the secondary winding also changes.

Transistors can be used of the old type - P416, GT308, they can be easily found in old receivers or televisions, and capacitors are used of the MBT or MBM type for an operating voltage of at least 400 V.

Transistors VT1, VT2 and resistors R5, R6, connected as shown in the diagram, are an analogue of dinistors and in this embodiment they work better than dinistors, but with a strong desire, instead of VT1, R5 and VT2, R6, you can put ordinary dinistors - type KN102A.

When assembling and adjusting the welding current regulator, do not forget that the control takes place under a voltage of 220V. Therefore, in order to prevent electric shock, all radio elements, as well as thyristor heat sinks, must be isolated from the case!

In practice, the above electronic welding current regulator has proven itself well.
The material from the Radioamator magazine was taken as a basis. - 2000. - No. 5 “Do-it-yourself welding transformer”.