In this article we will discuss about the design of welding transformer with the help of diagram.
A welding transformer has two circuits one is primary and other is secondary circuit. These two winding have no electrical connections but magnetically they are coupled together. The main function of transformer is to change high voltages low amperage ac power for welding. The input voltage to transformer may be 440 V or 220 V. The open circuit voltage at the output side of the set is usually 10 to 100 V and output current may be 600 A. The welding set has not rotating part. It is either air cooled or oil cooled. High amperage sets are oil cooled.
For small fabrication or repair job, a single phase 220 V input transformer set is used but for higher working loads a three phase (440 input) transformer welding set is used. The welding circuits are properly earthed to protect the welder in the event of a breakdown in the transformer and causing main supply voltage to come into contact with welding side circuit of the transformer. The welding side provides current setting range.
The amount of current can be adjusted by inserting a reactance coil into the circuit. The reactor is generally fit on the electrode side of the secondary coil.
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The welding plant provides current setting range, its output current for welding in the machine depending upon the electrode size or job thickness.
Availability of wheels, handles for transportation and sling elements permit easy transportation of the transformer.
At 70 V voltage the transformer is an ideal device for welding low thickness metals. Moreover at this voltage stable ignition and arc burning are provided even at corrosion-touched and very dirty products. Reliable insulation and relatively small weight make it unbeatable in operation both in factory environment as well as in the field under a shed.