Differential transformer core for pulse currents

A ground fault circuit interruptor comprising:

• a transformer core having a plurality of coaxially wound interleaved strips of magnetically permeable material for producing a rounded hysteresis loop;
• a primary winding having at least one pair of wires passing through the core and connectable at a first end thereof to a voltage source and at an opposite end thereof to a load;
• a secondary winding wound on the core;
• and
• means connected in circuit with the secondary winding for interrupting current flow through a load in response to a preselected differential current flow through the wires resulting from fault current flowing from one of the wires to ground.

A method for interrupting a power circuit, in response to accidental contact, by an object with the circuit, thus causing a fault current, the method comprising the steps of:

• coaxially winding a plurality of interleaved layers of magnetically permeable material to form a core having a rounded hysteresis loop;
• positioning a primary winding through the core, the winding being connectable at a first end thereof to a voltage source and at an opposite end thereof to a load;
• positioning a secondary winding on the core;
• connecting an impedance across the secondary winding to form a resonant circuit therewith;
• and
• connecting the resonant circuit to an electromagnetic circuit breaker, the latter being connected in circuit with the primary winding, for interrupting the power circuit after a few cycles of the fault current.

Apparatus comprising in combination,

• a transformer core comprising a plurality of interleaved layers coaxially wound in a closed path, the layers being fabricated from magnetically permeable material of relatively low and similar coercivity, the core producing a rounded hysteresis loop,
• a primary winding comprising at least one pair of wires passing through the core and connectable at a first end thereof to a voltage source and at an opposite end thereof to a load,
• a secondary winding wound on the core, and
• means connected across the secondary winding for interrupting current flow through a load in response to a preselected differential current flow in the wires.

Apparatus comprising in combination,

• a transformer core comprising a plurality of interleaved layers coaxially wound in a closed path, the layers being fabricated from magnetically permeable material of relatively low and similar coercivity, the core producing a rounded hysteresis loop,
• a primary winding comprising at least one pair of wires passing through the core and connectable at a first end thereof to a voltage source and at an opposite end thereof to a load,
• a secondary winding wound on the core,
• circuit breaking means connected in circuit with the wires, and
• means connected in circuit with the secondary winding for forming a resonant circuit therewith in response to a preselected differential current flow through the wires thus actuating the circuit breaking means after a few cycles of resonance.