Brazing technology for distribution transformers

Brazing technology for distribution transformers

Vol. 4 Issue 1
Company overview

Oxyweld, a leading Italian manufacturer of oxyhydrogen gas generators for brazing, marked its 36th anniversary and today, thanks to its experience, supports many transformer producers and transformer repairs in more than 60 countries. Oxyweld’s brazing technologies turn distilled water into gas and replace the conventional oxy-fuel cylinders (i.e. the most common oxy-acetylene or oxy-propane). Thanks to the flame’s properties, the system is specific for brazing copper, brass, aluminium, bus bars, cables, wires and flat wires, from small sizes up to big cross sections. The same flame is also used to remove the resin from the CTC in power industry.

Distribution transformers are strategic components in power networks and their longevity has a big impact on grid reliability. Often transformers fail due to incorrect brazing resulting in bad repercussions for the manufacturer and high repair costs. Obvuiously, the reputation damage and future loss are not computable. Nowadays, the best performers in the market are those OEMs able to provide reliable products, with a long duration life.

When it comes to brazing with conventional old gas cylinders, the quality control entirely depends on the operator and his ability to adjust the two gases, and on the quality of the gases purchased – with high risks involved.

The operators often have to braze as best as they can, sometimes having only a basic training, but still this process is not standardizable. There are too many variables under the responsibility of the worker. A perfect adjustment of the two gases is extremely important, otherwise the brazed area, if checked with a microscope, will in most of the cases be too much oxidized and not entirely filled with the brazing material, and there will be plenty of empty spots where there is no electrical conductivity and the joint is weak. This directly affects the performance of the transformer.

This risk can be overcome with an Oweld gas generator where the two gases are premixed automatically by the machine and the flame gets a perfect stoichiometric ratio. The flame’s pureness is guaranteed because it comes from distilled water, entirely independent from gas suppliers. This automation ensures superior brazing and an effective reduction of the empty spaces between the two conductors and improved electrical conductivity and stength of the joint accordingly.

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