Correct Answer - Option 1 : Low voltage, high current
Arc Welding Machines:
Welding cannot be done directly from the supply mains.
To facilitate the welding process special welding machines are used which provided currents of various characteristics.
The use of such machines is essential for the following reasons :
- To convert AC supply into DC supply when DC welding is desired.
- To reduce the high supply voltage to a safer and suitable voltage for welding purposes.
- To provide the high current necessary for arc welding without drawing a correspondingly high current from the supply mains.
- To provide suitable voltage/current relationships necessary for arc welding at minimum cost.
Arc Welding Transformer as an AC Welding Machines:
It consists of a step-down transformer (low voltage, high current) with a tapped secondary having an adjustable reactor in series for obtaining drooping V/I characteristics.
The secondary is tapped to give different voltage/ current settings.
Advantages:
- This AC welder can be operated from either a single-phase or 3-phase supply.
- Low initial cost
- Low operation and maintenance cost
- Low wear
- No arc blow
Disadvantages:
- Its polarity cannot be changed
- It is not suitable for welding cast iron and non-ferrous metals.
