Patent ID: 6346817
Filing Date: 2002-02-12
Classification: G01R

Abstract:
A float current probe for measuring a float current flowing in a conductor, comprising:a core adapted to be magnetically coupled to the conductor; an excitation winding magnetically coupled to the core; a field cancellation winding magnetically coupled to the core; a switch circuit coupled to the excitation winding, for controllably energizing and de-energizing the excitation winding in selectable forward and reverse polarity successively; a detecting device coupled to the excitation winding, for detecting when energy in the excitation winding reaches a predetermined threshold corresponding to a saturated core condition; a timer responsive to the detecting device, and measuring first and second delays needed to saturate the core as a result of the excitation winding being energized through the switch circuit in the forward and reverse polarity successively; a computing device for determining a magnetic field induced by the conductor based on the first and second delays measured by the timer; and a current source coupled to the field cancellation winding, for energizing the field cancellation winding with a current level and direction as a function of the magnetic field computed by the computing device, and substantially cancelling the magnetic field induced by the conductor; wherein the current level is representative of the float current in the conductor.