Welding machine from two transformers

 
Welding machine from two transformers
    A.N. Zhurenkov, Zaporozhye
 
   The article describes a DC welding machine of two transformers with the division of the primary winding into two, 37 V each with an additional 110 V outlet, and the secondary - into two 50 V each for alternating operation during each period through the rectifier diodes for direct current welding. The option of parallel connection of secondary windings for AC welding is also possible. This technical solution made it possible to wind the primary windings with a wire of the required cross-section with fewer turns, and the secondary windings with a thinner wire providing the required total cross-section, which greatly facilitated the winding and laying of the wire.
 
   Сварочный аппарат на базе трансформатора  In the "Electric" magazine, the design of welding transformers from two LATRs, several transformers from televisions and other options were described. In a series of articles by I. Zubal "Do-it-yourself welding transformer", many interesting solutions and recommendations are given. A welding machine of two 10 A LATRs can also be manufactured with standard LATR windings as the primary winding. This provides the power of the apparatus of 4.4 kW. When installing LATRs vertically, a ring 20 mm wide should be laid between the contacting ends, for example, made of fiberboard impregnated with varnish. Connect the windings in parallel and in phase so that the magnetic fluxes have the same direction. Bare trolley should be covered with epoxy varnish. To improve the cooling of the primary winding, wind 3-4 turns of a rope with a diameter of 4 ... 5 mm on each outer part of the LATRs. After that, wind the secondary winding on the recommendation of I. Zubal.

When installing LATRs according to the "eared" type, three wooden spacers with a height of 15 ... 20 mm, impregnated with varnish, must be laid between them. After that, tie the LATRs together with a rope with a diameter of 4 ... 5 mm, evenly distributing 4-6 turns along the height. Connect the primary windings in series and in phase so that at the point of contact of the LATRs, the magnetic fluxes have one direction. The secondary winding can be completely wound through the holes of the LATRs or consist of two halves, wound on each of them and connected in phase. In this case, the primary windings will be better cooled.

The proposed design is intended for direct current welding and is made of two chokes with transformer iron USh40x80. The total cross-section of the core is 64 cm2, which is quite enough for a welding transformer. The design uses standard coil frames and fasteners without alteration, which minimized the use of additional materials and labor costs for manufacturing.

  The coils of both transformers must be identical. The primary windings of each transformer are rated at 137 V with 110 V taps and each have 221 turns tapped from 161 turns.  Конструкция сварочного трансформатора These windings are wound with a PEV-2 wire with a diameter of 2.0 mm. The secondary windings are rated for 50 V each at a voltage of 110 V on the primary windings and contain 75 turns of PBD wire with a diameter of 3.0 mm. Insulating gaskets made of one layer of thin press-board are laid between the windings. After winding, the coils are alternately immersed in a container with varnish heated to a temperature of 50 ... 60 ° C for 10 minutes for impregnation. Схема сварочного трансформатора After drying, the coils are loaded with transformer iron over the cover, fastened with standard fastening material and installed on a metal base. In this case, it is necessary to take into account the identity of the installation of the transformers so that the direction of the magnetic fluxes in the contacting parts of the magnetic circuits coincides. 20 diodes of the rectifier type D242A are fixed on an aluminum plate with dimensions of 300 × 140 mm and a thickness of 4 mm without insulating gaskets, since "+" is connected to the "ground" when welding with direct current. The anodes of the diodes are connected to the terminals of the secondary windings with individual mounting conductors with a cross section of 1.5 mm2.  

 The electrical diagram of the welding machine is shown in the figure. Switches SA1 and SA2 make it possible to obtain voltages of 50 V, 44 V and 37 V on the secondary windings. Considering that the voltages of these windings during each period are supplied to the output through the diodes alternately, the current of each winding is half the welding current. This made it possible to wind the secondary windings with a thinner wire, which makes it easier to wind and lay. By connecting the secondary windings in parallel, the device without diodes can be used for operation on alternating current.

Small dimensions and weight create certain convenience in its operation, at the same time it limits the use of electrodes with a diameter of more than 3 mm. The design of the welding machine is shown in the photo.

Based on materials from the "Electric" magazine

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