Current transforming circuits
AssigneeTokyo Shibaura Denki Kabushiki Kaisha
InventorsTeruhiko Ito, Haruo Takahashi
Life of this patent
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Abstract
Current transforming apparatus comprising a current transformer and means for developing a current substantially expressed by a.multidot.I.sub.2, wherein I.sub.2 denotes the secondary current of the current transformer. Impedance means is connected in series to a load of the current transformer and has an impedance (Z.sub.2 +Z.sub.L)/(a-1), wherein Z.sub.2 is the secondary leakage impedance of the current transformer and Z.sub.L is an impedance of the load. A current-voltage converter may be employed as the load of the current transformer.
Claims22
A current transforming circuit comprising:
- primary winding means;
- a first secondary winding coupled magnetically to said primary winding means to form a first current transformer;
- means for developing a current substantially equal to (a.multidot.I.sub.2) wherein a is an arbitrary number greater than 1 and I.sub.2 is the secondary current in said first secondary winding;
- impedance means adapted to be connected to load means to form a series connection therewith across said first secondary winding, said impedance means having an impedance of approximately (Z.sub.2 +Z.sub.L)/(a-1) wherein Z.sub.2 is the leakage impedance of said first secondary winding and Z.sub.L is the impedance of said load means;
- and
- said current developing means being connected to said impedance means such that a current substantially equal to (I.sub.2 -a.multidot.I.sub.2) flows therethrough to substantially null voltages induced in the first secondary winding due to exciting currents present therein.
A current transforming circuit comprising:
- primary winding means;
- a first secondary winding coupled magnetically to said primary winding means to form a first current transformer;
- impedance means;
- current-to-voltage converting means having substantially zero input impedance, said current-to-voltage converting means being connected to said impedance means to form a series connection therewith across said first secondary winding for developing a voltage substantially proportional to the secondary current in the first secondary winding;
- and
- current developing means connected to apply a current to said impedance means, in cooperation with the secondary current in said first secondary winding, flowing such that the total current through said impedance means functions to substantially null the voltages induced in said first secondary winding due to the leakage impedance thereof.
A current transforming circuit comprising:
- a primary winding;
- first and second secondary windings magnetically coupled to said primary winding to form, respectively first and second current transformers which develop a first secondary current I.sub.2 and a second secondary current I.sub.3, wherein I.sub.3 is greater than I.sub.2 ;
- means having input impedance for measuring electrical quantity;
- resistor means connected to said means to form a series connection across said first secondary winding, the resistor means having an impedance approximately equal to (Z.sub.2 +Z.sub.L)/(a-1), where Z.sub.2 is the leakage impedance of said first secondary winding, Z.sub.L is said input impedance and a is I.sub.3 /I.sub.2 ;
- and
- means for connecting said resistor means to said second secondary winding such that a current substantially equal to I.sub.2 -I.sub.3 flows through said resistor means.
Dependencies are inferred from the claim text.