Current measuring device

Claim 2

A current measuring device for measuring a current flowing in a conductor by inductive coupling to the conductor, said device comprising an E-shaped core of magnetic material having first and second outer legs and a center leg spaced from said second outer leg sufficiently to provide a space therebetween for the reception of a conductor carrying the current to be measured, a bar movably associated with said E-shaped core and movable between a first position in which the bar is displaced from the end of said second outer leg sufficiently to provide for the insertion of a conductor therein to a normal position in which it is in engagement with said first outer leg and said center leg but is displaced from said second outer leg by an air gap, a pair of windings disposed on said first outer leg, means for alternately energizing said windings to cause flux flow in opposite directions, and means for measuring any difference in voltage across said windings resulting from the effect of flux flowing in said center leg because of current flow in said conductor.

Claim 3

The current measuring device of claim 1 in which said bar is slidably associated with said E-shaped core and is in continuous slidable engagement with said first outer leg and said center leg.

Claim 4

The current measuring device of claim 2 in which said bar extends across the ends of said first outer leg and said center leg in slidable engagement with the ends of said leg.

Claim 5

The current measuring device of claim 1 in which the energization of each of said windings is controlled by a separate transistor connected in series therewith with means for alternately rendering said transistors conductive to cause alternate energization of said windings.

Claim 6

The current measuring device of claim 4 in which the means for causing said transistors to be alternately conductive comprises two additional windings inductively associated with said previously named windings and connected to control electrodes of said transistors.

Claim 7

The current measuring device of claim 4 in which each of said transistors has a further transistor in series therewith to prevent clipping of the voltage peaks resulting from the alternate energization of said windings.

Claim 8

The current measuring device of claim 4 in which the means for measuring any difference in voltage across said windings comprises a further transistor having a control electrode thereof connected to an output electrode of one of said previously named transistors.

Claim 9

A current measuring device for measuring a current flowing in a conductor by inductive coupling to the conductor, said device comprising a core of magnetic material having first and second legs, a bar movably associated with said core and movable between a first position in which the bar is displaced from the end of one of said legs sufficiently to provide for the insertion of a conductor into said core to a normal position in which it forms a substantial part of the magnetic path of said core, a pair of windings disposed on said first leg, means including a pair of transistors, each controlling the energization of one of said windings, to cause said windings to be alternately energized to cause flux flow in opposite directions, means responsive to the change in the magnetic field in the core including a pair of further transistors, one in series with each of the previously named transistors, to prevent clipping of the voltage peaks resulting from the alternate energization of said windings, and means for measuring any difference in voltage across said windings resulting from the effect of flux flowing in said first leg because of current flow in said conductor, said last named means comprising a further transistor having a control electrode thereof connected to one of said transistors of the first named pair of transistors.

Claim 10

A current measuring device for measuring a current flowing in a conductor by inductive coupling to the conductor, said device comprising a core of magnetic material having first and second legs, a bar movably associated with said core and movable between a first position in which the bar is displaced from the end of one of said legs sufficiently to provide for the insertion of a conductor into said core to a normal position in which it forms a substantial part of the magnetic path of said core, a pair of windings disposed on said first leg, means including a pair of transistors, each controlling the energization of one of said windings, to cause said windings to be alternately energized to cause flux flow in opposite directions, means responsive to the change in the magnetic field in the core including a pair of further transistors, one in series with each of the previously named transistors, to prevent clipping of the voltage peaks resulting from the alternate energization of said windings, and means for measuring any difference in voltage across said windings resulting from the effect of flux flowing in said first leg because of current flow in said conductor, said last named means comprising a further transistor having a control electrode thereof connected to one of said transistors of the first named pair of transistors.