This question should be really easy that I'm afraid to ask, but I guess I miss understood the question.
An overcurrent relay is used to protect a circuit with a maximum 3-phase fault current of 8,000 A primary. A 400:5 current transformer ratio and a 5-A relay tap setting are selected. If the total secondary burden on the current transformer for the maximum fault condition is 1.10 ohm, the excitation voltage that must be developed by the current transformer is most nearly___.
Is/Ip = a = 400/5
which means Is = a(Ip), but the answer actually used 8000(5/400)=100A
Am I miss understanding the question?
An overcurrent relay is used to protect a circuit with a maximum 3-phase fault current of 8,000 A primary. A 400:5 current transformer ratio and a 5-A relay tap setting are selected. If the total secondary burden on the current transformer for the maximum fault condition is 1.10 ohm, the excitation voltage that must be developed by the current transformer is most nearly___.
Is/Ip = a = 400/5
which means Is = a(Ip), but the answer actually used 8000(5/400)=100A
Am I miss understanding the question?