Patent ID: 7227348
Filing Date: 2007-06-05
Classification: G01R

Abstract:
1. An apparatus for measuring alternating current in a conductor, the apparatus comprising first and second coil means having substantially the same turns-area product and substantially parallel axes, the first and second coil means being located on the circumference of a notional circle with the first coil means having its axis tangential to the circle and the second coil means having its axis extending radially of the circle, and third and fourth coil means also having substantially the same turns-area product and substantially parallel axes, the third and fourth coil means being located on the circumference of the notional circle close to the first and second coil means respectively, the third coil means having its axis extending radially of the circle and the fourth coil means having its axis tangential to the circle such that the first and third coil means form a closely adjacent first pair of coil means with substantially orthogonal axes and the second and fourth coil means form a closely adjacent second pair of coil means with substantially orthogonal axes, the first to fourth coil means being mounted on a support means configured to allow a conductor to be introduced into the centre of the said circle with the axis of the conductor normal to the plane containing the first to fourth coil means, the apparatus further comprising means electrically connecting the first and second coil means in series in anti-phase and the third and fourth coil means in series in anti-phase, and means for deriving the alternating current in the conductor as a function of the voltages induced in the series-connected first and second coil means and the series-connected third and fourth coil means.