Dear Kai,

Thanks for your reply,

I have dropped the idea of using parabolic curve fitting of current at maximum, minimum and middle value firing angles. As per my new plan...
1. RMS factor table calculated theoretically [discussed earlier] will be kept as it is in Code memory of micro.
2. When the caliberate routine is activated.
3. The current values at maximum, minimum and middle firing angles will be measured practically by firing the thyristor.
4. A new look up table will be generated by using the practically measured current values the new table will use the same trend of change in values as the theoretical RMS factor values in code memory. I am not sure if I could clearly express this new idea. If theres any confusion or wrong with new idea kindly do let me know.
5. The new table will be kept in I2C SEEPROM. When the system starts these table values will be loaded to XRAM for faster access during running the weld schedule.

Kindly do let me know your comments / suggestions regarding this new idea.

Thanks & Regards,
Prahlad Purohit