AC Rectified Welding Unit

 

Fig: 1

 

It consists of a transformer (single-or three-phase) and a rectifier unit as shown in Fig. 1. Such a unit has no moving parts, hence it has long life. The only moving part is the fan for cooling the transformer.

But this fan is not the basic part of the electrical system. Fig. 1 shows a single-phase full-wave rectified circuit of the welder. Silicon diodes are used for converting a.c. into d.c. These diodes are hermetically sealed and are almost ageless because they maintain rectifying characteristics indefinitely.

Such a transformer-rectifier welder is most adaptable for shield arc welding because it provides both d.c. and a.c. polarities. It is very efficient and quiet in operation.

 These welders are particularly suitable for the welding of

 (i) pipes in all positions

(ii) non-ferrous metals

(iii) low-alloy and corrosion-

heat and creep-resisting steel

(iv) mild steels in thin gauges.

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