Patent ID: 7511471

Claim:
A magnetic bridge power sensor comprising a magnetic bridge, the magnetic bridge including: a magnetic circuit 1 having two ends; magnetic circuits 21 a and 21 b each having two ends, one of the two ends of each of the magnetic circuits 21 a and 21 b being connected to one of the two ends of the magnetic circuit 1 ; magnetic circuits 22 b and 22 a each having two ends, one of the two ends of each of the magnetic circuits 22 b and 22 a being connected to the other end of the magnetic circuit 1 , the other ends of the magnetic circuits 22 b and 22 a being connected to the second magnetic circuits 21 a and 21 b , respectively; a magnetic circuit 2 having two ends, the two ends being connected to a connection point between the magnetic circuits 21 a and the magnetic circuits 22 b and to a connection point between the magnetic circuit 21 b and the magnetic circuit 22 a , respectively; an excitation coil 3 provided to be able to generate a magnetic flux in the magnetic circuit 2 ; and a magnetic flux detection coil 4 provided to be able to detect the magnetic flux in the magnetic circuit 1 , wherein a voltage of a measurement target alternating-current power line 5 is applied to the excitation coil 3 , and a current proportional to the voltage is carried to the excitation coil 3 , and an output of the detection coil 4 is synchronously detected by a signal having a phase synchronized with a phase of the voltage of the measurement target alternating-current power line 5 at a frequency twice as high as a frequency of the voltage of the measurement target alternating-current power line.