Symmetrical breaking current: It is the rms value of a a.c component of the current in the pole at the instant of contact separation.
Asymmetrical breaking current: It is the rms value of the total current comprising the a.c and d.c components of the current in the pole at the instant of contact separation.
Intern turn winding fault can be easily detect by differential protection relay. Also detect by buchholz relay (gas operated relay), cause buchholz relay is used to detect the internal fault of transformer.
EXAMIANS