Dear Jez,

Thanks for your reply,

Youve got a measured value for something which can be approximated by some polynomial,youve also got a predicted value and therefore an error which can also be approximated by a polynomial,so the aim is the minimise the error,a bit of calculus or even excell will do the rest.

Thats a good Idea to do some calculus say with excell and get a table that will match the measured and predicted values and then burn the micro with this table in it. The controller will sork fine with this transformer but what if this controller is put to some other transformer that shows some diffrent characteristics. When shipping a controller I have no idea about the customers transformer behaviour how to construct the look up table in that case. [ Its possible to have a function say TEACH in controller wich when activated can fire the thyristor at a couple of predermined firing angles and measure the obtained current but is it possilbe to construct a complete look up table from these 2 - 3 values. Its not possible to fire more than 3 cycles in TEACH fucntion since more cycles can lead to complete burning of electrodes if clients transformer capacity is high ].

Thanks & Regards,
Prahlad Purohit