Pulse arc stabilizer sdi 01. Welding arc pulse stabilizer. Special functions of switching voltage regulators

3.5.3. Extended circuit of the acoustic sensor Adjustment of the amplification of weak signals from the microphone BM1 is carried out by a variable resistor R6 (see Fig. 3.9). The lower the resistance of this resistor, the greater the gain of the transistor stage on the transistor VT1. At

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General scheme of electrical equipment Electrical equipment of cars is complex system interconnected electrical signaling, ignition, fuses, instrumentation, connecting wires. Rice.

2.6. Circuit of a sensitive video amplifier Those who are involved in the use of video monitoring circuits in a limited area will find this material useful. Touching possible options providing security in confined spaces, once again I want to note that it is not always cost-effective

Oscillator is a device that converts power frequency current low voltage into current high frequency(150-500 thousand Hz) and high voltage (2000-6000 V), the imposition of which on the welding circuit facilitates the excitation and stabilizes the arc during welding.

The main application of oscillators was found in argon-arc welding with an alternating current with a non-consumable electrode of metals of small thickness and in welding with electrodes with low ionizing properties of the coating. The schematic diagram of the OSPZ-2M oscillator is shown in Fig. 1.

The oscillator consists of an oscillatory circuit (capacitor C5, the movable winding of the high-frequency transformer and the arrester P is used as an induction coil) and two inductive choke coils DR1 and DR2, a step-up transformer PT, and a high-frequency HF transformer.

The oscillating circuit generates a high-frequency current and is inductively connected to the welding circuit through a high-frequency transformer, the terminals of the secondary windings of which are connected: one to the grounded terminal of the output panel, the other through the capacitor C6 and the fuse Pr2 to the second terminal. To protect the welder from injury electric shock a capacitor C6 is included in the circuit, the resistance of which prevents the passage of high voltage and low frequency current into the welding circuit. In case of a breakdown of the capacitor C6, a fuse Pr2 is included in the circuit. The OSPZ-2M oscillator is designed to be connected directly to a two-phase or single-phase network with a voltage of 220 V.

Rice. 1. : ST - welding transformer, Pr1, Pr2 - fuses, Dr1, Dr2 - chokes, C1 - C6 - capacitors, PT - step-up transformer, HFT - high-frequency transformer, R - arrester	Rice. 2. : Tr1 - welding transformer, Dr - choke, Tr2 - step-up transformer of the oscillator, P - arrester, C1 - circuit capacitor, C2 - protective circuit capacitor, L1 - self-induction coil, L2 - coupling coil

During normal operation, the oscillator crackles evenly, and due to the high voltage, the gap of the spark gap breaks down. The size of the spark gap should be 1.5-2 mm, which is adjusted by squeezing the electrodes with an adjusting screw. The voltage across the elements of the oscillator circuit reaches several thousand volts, therefore, the regulation must be performed with the oscillator turned off.

The oscillator must be registered with the local telecommunication inspectorate; during operation, monitor its correct connection to the power and welding circuit, as well as the good condition of the contacts; work with the casing on; remove the cover only during inspection or repair and with the mains disconnected; monitor the good condition of the working surfaces of the arrester, and if carbon deposits appear, clean them with emery paper. Oscillators with a primary voltage of 65 V are not recommended to be connected to the secondary terminals of welding transformers of the type TS, STN, TSD, STAN, since in this case the voltage in the circuit decreases during welding. To power the oscillator, you need to use a power transformer with a secondary voltage of 65-70 V.

The connection diagram of the M-3 and OS-1 oscillators to the STE-type welding transformer is shown in Fig. 2. Specifications oscillators are given in the table.

Oscillator Specifications

Pulse arc exciters

These are devices that serve to deliver synchronized pulses. increased voltage on the AC welding arc at the moment of polarity reversal. This greatly facilitates the re-ignition of the arc, which makes it possible to reduce the open circuit voltage of the transformer to 40-50 V.

Pulse exciters are used only for gas-shielded arc welding with a non-consumable electrode. Exciters from the high side are connected in parallel to the power supply network of the transformer (380 V), and at the output - parallel to the arc.

Powerful sequential exciters are used for submerged arc welding.

Pulse arc exciters are more stable in operation than oscillators, they do not create radio interference, but due to insufficient voltage (200-300 V), they do not provide arc ignition without the electrode contacting the product. Cases of combined use of an oscillator for the initial ignition of the arc and a pulsed exciter to maintain its subsequent stable combustion are also possible.

Welding arc stabilizer

To increase the productivity of manual arc welding and economical use of electricity, the SD-2 welding arc stabilizer has been created. The stabilizer maintains a stable burning of the welding arc when welding with an alternating current with a consumable electrode by applying a voltage to the arc at the beginning of each period of a voltage pulse.

The stabilizer expands the technological capabilities of the welding transformer and allows you to perform AC welding with UONI electrodes, manual arc welding with a non-consumable electrode of alloy steel and aluminum alloy products.

A diagram of the external electrical connections of the stabilizer is shown in Fig. 3, a, the oscillogram of the stabilizing pulse is shown in Fig. 3, b.

Welding with the use of a stabilizer makes it possible to more economically use electricity, expand the technological possibilities of using a welding transformer, reduce operating costs, and eliminate magnetic blast.

Discharge-250 welding device. This device is developed on the basis of a TSM-250 welding transformer and a welding arc stabilizer that emits pulses with a frequency of 100 Hz.

The functional diagram of the welding device and the oscillogram of the open circuit voltage at the output of the device are shown in Fig. 4, a, b.

Rice. 3. : a - diagram: 1 - stabilizer, 2 - cooking transformer, 3 - electrode, 4 - product; b - oscillogram: 1 - stabilizing pulse, 2 - voltage on the secondary winding of the transformer	Rice. 4. a - device diagram; b - oscillogram of open circuit voltage at the output of the device

The "Discharge-250" device is intended for manual AC welding with consumable electrodes of any type, including those intended for DC welding. The device can be used for welding with non-consumable electrodes, for example, when welding aluminum.

Stable burning of the arc is ensured by applying a voltage pulse of straight polarity to the arc at the beginning of each half of the alternating voltage period of the welding transformer, i.e., coinciding with the polarity of the specified voltage.

Pulse arc stabilizer (ISGD) is a generator of high voltage peak pulses applied to the arc at the moment of current zero crossing. This ensures reliable re-ignition of the arc, which guarantees a high stability of the AC arc.

Consider the diagram of the SD-3 stabilizer (Figure 5.31). Its main parts are a power transformer G, a switching capacitor WITH and thyristor switch VS 1, VS 2 with control system A. The stabilizer feeds the arc parallel to the main source G- welding transformer. First, let us analyze its operation when the welding transformer is idle. At the beginning of the half-cycle, the thyristor opens VS 1, as a result, a current pulse will pass through the circuit shown by the thin line. In this case, according to the current EMF of the transformer T source G create a charge on the capacitor with the polarity indicated in the figure. The capacitor charge current increases until the voltage across it equals the total voltage of the transformer G and the source G. After that, the current begins to decrease, which will cause the appearance of self-induction EMF in the circuit, which tends to keep the current unchanged. Therefore, the charge of the capacitor WITH will continue until the voltage across the capacitor reaches double the supply voltage. Capacitor charge voltage applied to VS 1 in the opposite direction, will close the thyristor. In the second half cycle, the thyristor opens VS 2, and the impulse current will go in the opposite direction. In this case, the impulse will already be more powerful, since it is caused by the concordant action of the EMF of the transformers T and G, as well as the charge of the capacitor WITH. As a result, the capacitor will be recharged to an even higher level. Such a resonant nature of the overcharge makes it possible to obtain stabilizing voltage pulses with an amplitude of about 200 V at the interelectrode gap at a relatively low voltage of the supply transformer of about 40 V (Figure 5.31, b). The pulse generation frequency is 100 Hz. The voltage from the main source is also applied to the interelectrode gap (Figure 5.31, d). When indicated in the figure. 5.31, transformer phasing T and G the polarities of the voltages applied to the interelectrode gap from the main source (shown by the dashed line) and from the stabilizer (thin line) are opposite. This inclusion of the stabilizer is called counter. The figure. 5.31, c shows the voltage across the interelectrode gap with the combined action of the stabilizer and the main source.

Drawing. 5.31 - Pulse arc stabilizer

If you change the phasing of the main transformer G or stabilizer, then the polarity of the voltages on the arc from the main source and from the stabilizer will coincide (Figure 5.31, a). Such a connection is called a consonant, it is used in the construction of other stabilizers. Reignition occurs at the moment of applying a stabilizing pulse, usually the ignition time does not exceed 0.1 ms.

With the opposite connection, the stabilizing impulse, although it does not coincide in the direction with the voltage of the transformer G, also contributes to re-ignition (see Figure 5.31, c). At the same time, the drawing. 5.31, but it can be seen that part of the impulse current passing through the secondary winding G(thin line), coincides with the intrinsic current of this winding (dashed line) and therefore does not prevent its current from rapidly increasing to the value required for re-ignition.

Stabilizer SD-3 can be used both for manual welding with a covered electrode and for welding aluminum with a non-consumable electrode. The control system starts the stabilizer only after the arc has been struck. After breaking the arc, it works no more than 1 second, which increases labor safety.

The described autonomous stabilizer can be used in combination with any transformer for manual welding with an open-circuit voltage of at least 60 V, while the arc stability increases so much that it becomes possible to weld on alternating current with electrodes with a calcium fluoride coating, in which the stabilizing properties are considered to be low.

It is more efficient to use stabilizers built into the source body. Discharge-160, Discharge-250 and TDK-315 transformers are produced with built-in stabilizers; they have a reactive winding of three sections. The range switch, providing first a consent and then an opposite connection of the reactive winding with the primary, allows you to increase the current in seven steps. Thanks to the use of a pulse stabilizer, it became possible to reduce the open-circuit voltage of transformers to 45 V. And this, in turn, sharply reduced the current consumed from the network and the mass of the transformers. Unlike stand-alone, the built-in stabilizer is triggered using dual control - not only due to feedback by voltage, but also by current. This increases the reliability of its operation, in particular, prevents false alarms during short circuits by drops of electrode metal. Transformers TDM-402 with movable windings and TDM-201 with a magnetic shunt are produced with a built-in stabilizer.

The invention relates to welding production and can be used in the production or modernization of welding power sources. The purpose of the invention is to increase the power and stability of the pulses that ignite the arc by changing the circuit of the key stage, which makes it possible to improve the operational properties of the stabilizer, to expand the scope of its application. The pulse stabilizer of the welding arc contains two transformers 1, 2, two thyristors 7, 8, four diodes 10 13, a capacitor 9, a resistor 14. 1 ill.

The invention relates to welding production and can be used in the production or modernization of welding power sources. The aim of the invention is to develop a device that provides increased power and stability of pulses igniting the arc by changing the circuit of the key stage, which improves the operational properties of the stabilizer, expands the scope of its application. To stabilize the AC arc welding process, at the beginning of each half-period of the welding voltage, a short-term powerful current pulse is applied to the arc, formed by overcharging the capacitor connected to the arc power circuit using thyristor switches. In the known circuit, the capacitor cannot be recharged to the amplitude values ​​of the voltages supplying it, which reduces the power of the pulse that ignites the arc. In this case, the power of this pulse is affected by the moment when the thyristors open relative to the beginning of the half-period of the voltage supplying the arc. This is due to the early closing of the thyristors, since the charging current of the capacitor flowing through them is determined by the reactance of the capacitor. This current can keep the thyristor open as long as it exceeds the holding current of the thyristors in the open state. The specified condition is provided (after the trigger pulse arrives at the control electrode of the thyristor) for a very short time, after which the thyristor closes. The drawing shows the electrical circuit of the stabilizer. Positions 1 and 2 respectively designate additional and welding transformers; 3 and 4 points of connection to the circuits of the key thyristor stage; 5 and 6, respectively, a welding electrode and a work piece to be welded; 7 and 8 key thyristors; 9 capacitor; 10 and 11 power diodes; 12 and 13 low-power diodes; 14 resistor. The diagram does not show a device for generating control pulses that turn on thyristors. Control signals U y from this device are fed to the corresponding electrodes of the thyristors 7 and 8. The device operates as follows. When a positive half-wave of voltage appears on the arc and turns on at the beginning of this half-period of thyristor 8, capacitor 9 will instantly charge through it and diode 11. But the thyristor remains open, since until the moment when the voltage amplitude value is reached on the secondary winding of transformer 1, the current through the thyristor flows through two circuits: thyristor 8 diode 11 capacitor 9 and thyristor 8 diode 13 resistor 14. The current flowing through the first circuit is very small (insufficient to keep the thyristor open), and in the second circuit it is sufficient to keep the thyristor open. As the voltage of a given half-period rises to its peak value, the capacitor is recharged to the sum of this voltage with the voltage across the arc. Further, the voltage on the secondary winding of the transformer 1 will begin to decrease and the voltage of the charged capacitor 9 will close the diode 13, which will cause the thyristor 8 to turn off and the capacitor 9 will remain charged by the extreme value of the sum of these voltages until the polarity of the voltage on the arc changes. After the polarity change at the beginning of the next half-period, thyristor 7 will open with a control pulse and the capacitor will instantly recharge to the sum of the voltages acting at that moment on the secondary windings of transformers 1 and 2. Diode 12 opens, keeping thyristor 7 open until the peak value of the voltage on the secondary winding of transformer 1 is reached. Accordingly, the capacitor 9 is recharged to the sum of the peak value of the specified voltage and the voltage across the arc. The introduction of these elements into electrical circuit stabilizer allows you to increase the pulse amplitude in two or more times and make it (swing) independent of the moment when the thyristors open relative to the beginning of the half-period of the voltage on the arc. In the above reasoning, only the amplitude value of the voltage on the secondary winding of the transformer 1 is mentioned and nothing is said about the nature of the change in the voltage across the arc. The fact is that the electric arc has a significant stabilizing ability and during its burning, the alternating voltage across it has a rectangular shape with a flat top (meander), i.e. the voltage across the arc during a half-period is practically constant in amplitude (does not change in magnitude) and does not affect the nature of the charge of the capacitor 9. The application of the invention made it possible to increase the amplitude of the impulse igniting the arc by 1.8.2 times, to stabilize it when changing over a wide range of the opening moment thyristors relative to the beginning of the half-cycle of the alternating voltage on the arc. Due to the provision of these effects, it is possible to intensively destroy the oxide film during argon-arc welding of aluminum and its alloys, to stabilize the arc burning process in wide range welding currents, especially in the direction of its reduction. The high quality of the formation of the weld was noted.

Claim

PULSE STABILIZER OF THE WELDING ARC, including a series-connected secondary winding of the welding transformer, a circuit of counter-parallel connected thyristors with their control circuit, a capacitor and a secondary winding of an additional transformer, connected according to the secondary winding of the welding transformer, which is connected to welding electrodes, characterized in that two power and two low-power diodes and a resistor are introduced into it, and the power diodes are connected in series according to the thyristors, the junction point of one thyristor and the cathode of the first power diode is connected to the cathode of the first low-power diode, and the junction point of the cathode of the other thyristor and the anode of the second the power diode is connected to the anode of the second low-power diode, the anode and cathode of the first and second low-power diodes, respectively, are connected through a resistor to the capacitor plate connected to the secondary winding of the additional transformer.