My question is why three types of dotted are required for three legged transformer.The mutual windings for three legs are negative.
M12=M21=M31 all are negative, why?

 

Can you post an example?
Dots indicated on a transformer winding usually mean the same winding direction point.?
Max.

 

Please see the slides # 34.

 

Would it be possible to mention on which page of this 97 sheet haystack you hid the needle?

 

Slide no. 34