Answer / yogesh

10 % increase in voltage gives you 50 % increase in
excitation current is called knee point voltage.

Answer / pundlik wanwe

for getting knee pint voltage of CT following is the procedure.
voltage source is connected to the CT secondary and slowly voltage is increased. milli ampere current is measured in the secondary circuit. at initial increase in current will be linear with voltage which is operating range. if again the voltage is increased further, at some point 10% increase in voltage causes 50% increased in current. this point is called Knee point of CT. Knee point is very important for the protection CT as after this point CT core is on the verge of saturation, which is not healthy region for protection.

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