Repair of the welding machine TAE101U2. Scheme, description

Free technical library

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

Repair of the welding machine TAE101U2. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / welding equipment

Comments on the article

The industry has produced a large number of welding machines with electronic current control. But schematic diagrams and explanations for them can not be found. The author encountered this problem when repairing a neighbor's TDE 101U2 welding machine.

Despite the small number of parts (Fig. 1), the device has a complex control scheme.

Repair of welding machine TAE101U2

As you know, thyristors are controlled by current (control voltage is usually 2 - 5 V) and are non-lockable current switches. The current of the welding machine is regulated indirectly. By changing the period of current flow in the primary winding, a change in the current in the secondary winding is achieved. Since the current in the primary winding is small (up to 20 A), this option was introduced in TDE 101U2.

Operation of the control circuit. The alternating mains voltage of 220 V is supplied to the step-down transformer T2 (winding W1, the transformer is phased in phase with respect to T1). From the winding W2 T2 through the current-limiting resistance R1, the current flows to VD1 - VD4. At the output of the bridge VD1 - VD4, the rectified voltage (Fig. 2, b) is "cut" by the zener diode VD5 (at the stabilization voltage level of 22 V) (Fig. 2, c), as a result, it has a trapezoidal pulse shape.

Repair of welding machine TAE101U2

Capacitor C1 is charged through R7 (current adjustment is set on the control panel), R13, R6 and winding W1 T3. As a comparison element, a unijunction transistor VT1 is used. When the voltage on the capacitor C1 reaches the threshold voltage VT1, the transistor opens, and C1 is discharged through the transition E-B1 VT1, W1 T3. On the primary winding W1 T3, a pulse is formed with a duration of 0,7 - 4 ms (depending on the position of the R7 slider on the control panel). Since the duration of the trapezoidal pulses is 10 ms, with a minimum resistance R7, the duration of the generated pulses will be 0,7 ms. In this case, several pulses are generated at regular intervals (Fig. 2d).

To unlock the power thyristors VS1, VS2 in the control circuit, low-power thyristors VS1, VS2 are used as a key. On the windings W2, W3 T3, due to self-induction, the EMF of the pulses generated by the control circuit on W1 T3 is induced. Since W2, W3 are wound out of phase, then the thyristors VS1 and VS2 will be unlocked in one of the phases of the alternating voltage (Fig. 2, a) induced on the windings W3, W4 T2.

In this circuit, two main properties of the thyristor work are very successfully used. First, if the voltage at the anode-cathode of the thyristor is out of phase, then the current does not flow through it, even if the thyristor trigger pulses are applied to the control electrode. The second thyristors are unlocked by the first control pulse, locked if the current through the anode-cathode is zero. Therefore, several pulses generated by the control circuit based on VT1 do not affect the already open thyristor. As soon as current begins to flow through the open VS1 or VS2, VS3 or VS4 open (depending on the phase of the mains voltage) and the primary winding W1, W2 T1 is connected through an open thyristor. In the closed state, the primary current flows through the inductor L1.

The inductor L1 is necessary to reduce the impulse noise that occurs in the network, due to the unlocking of the thyristors VS3, VS4. On the secondary windings W3, W4 we obtain a voltage (Fig. 2,g), which has the form of sawtooth pulses. The shape of these pulses varies depending on the firing angle VS3, VS4. With a small opening angle VS1, VS2, the current in the secondary winding is limited. With a large opening angle, it is maximum, reaching 110 A. Unfortunately, the circuit has a number of disadvantages.

Low power VD1 - VD4, insufficient filtering of impulse noise (occurring during arcing) in the power supply circuit of the control circuit, which leads to failures in the control circuit, unprotected thyristors VS1 and VS2 from reverse currents in the control electrode circuit, lack of a toggle switch to turn on the device. These shortcomings lead to the failure of the circuit elements.

During the repair, the author recommends that you follow the safety rules, use ungrounded measuring equipment, since the control circuit is not galvanically isolated from the network.

Author: I.N. Pronsky

See other articles Section welding equipment.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Solidification of bulk substances 30.04.2024

There are quite a few mysteries in the world of science, and one of them is the strange behavior of bulk materials. They may behave like a solid but suddenly turn into a flowing liquid. This phenomenon has attracted the attention of many researchers, and we may finally be getting closer to solving this mystery. Imagine sand in an hourglass. It usually flows freely, but in some cases its particles begin to get stuck, turning from a liquid to a solid. This transition has important implications for many areas, from drug production to construction. Researchers from the USA have attempted to describe this phenomenon and come closer to understanding it. In the study, the scientists conducted simulations in the laboratory using data from bags of polystyrene beads. They found that the vibrations within these sets had specific frequencies, meaning that only certain types of vibrations could travel through the material. Received ... >>

Implanted brain stimulator 30.04.2024

In recent years, scientific research in the field of neurotechnology has made enormous progress, opening new horizons for the treatment of various psychiatric and neurological disorders. One of the significant achievements was the creation of the smallest implanted brain stimulator, presented by a laboratory at Rice University. Called Digitally Programmable Over-brain Therapeutic (DOT), this innovative device promises to revolutionize treatments by providing more autonomy and accessibility to patients. The implant, developed in collaboration with Motif Neurotech and clinicians, introduces an innovative approach to brain stimulation. It is powered through an external transmitter using magnetoelectric power transfer, eliminating the need for wires and large batteries typical of existing technologies. This makes the procedure less invasive and provides more opportunities to improve patients' quality of life. In addition to its use in treatment, resist ... >>

The perception of time depends on what one is looking at 29.04.2024

Research in the field of the psychology of time continues to surprise us with its results. Recent discoveries by scientists from George Mason University (USA) turned out to be quite remarkable: they discovered that what we look at can greatly influence our sense of time. During the experiment, 52 participants took a series of tests, estimating the duration of viewing various images. The results were surprising: the size and detail of the images had a significant impact on the perception of time. Larger, less cluttered scenes created the illusion of time slowing down, while smaller, busier images gave the feeling of time speeding up. Researchers suggest that visual clutter or detail overload can make it difficult to perceive the world around us, which in turn can lead to faster perception of time. Thus, it was shown that our perception of time is closely related to what we look at. Larger and smaller ... >>

Random news from the Archive

Echo sounder for drone 08.03.2020

Bats are able to fly through total darkness using echolocation. So why not use the same principle in unmanned vehicles? Scientists at Purdue University have taken this question to heart and developed a system that allows a drone to navigate in space using just four microphones and a speaker.

The principle of the system is incredibly simple. The speaker emits a sound, this sound is reflected from the surrounding objects and is picked up by the microphones. The speed of sound is constant. This means that by the time during which the microphone picks up the reflected sound wave, it is possible, using simple mathematical calculations, to determine the distance to the object from which the sound was reflected. With four microphones at your disposal, you can create a detailed XNUMXD map of the environment around the drone. And all this - without a single camera. Moreover, the technology is able to work not only in the air. It can be effectively used on land or water equipment.

Of course, the development is not yet perfect. Currently, the drone is supposed to hover in place during sound scanning, but in the future, the developers plan to upgrade the system by teaching the drone's on-board computer to perform calculations in motion.

According to scientists, in some cases, echolocation works more reliably than visual pattern recognition. Sometimes the camera can be wrong. An unmanned drone "sees" a non-existent wall in front of it and hangs in indecision. Echolocation has no such problems. When used in conjunction with existing computer vision systems, unmanned vehicles can achieve amazing accuracy.

Other interesting news:

▪ US space exploration

▪ Heart attack awaits on the road

▪ Concrete with nanoparticles will make the air cleaner

▪ ASUS Eee Tablet

▪ Smartphone ZTE Grand S3 with an iris scanner

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Dosimeters. Selection of articles

▪ article by Leonardo da Vinci. Famous aphorisms

▪ article Who ordered to build another wall around the besieged city for their own protection? Detailed answer

▪ article Hydrotechnician. Job description

▪ article Amplifier on 4 transistors with floating power supply. Encyclopedia of radio electronics and electrical engineering

▪ article Unusual photography. Chemical experience

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews