Method and apparatus for magnetizing and demagnetizing current transformers and magnetic bodies

Apparatus for establishing a preferred induction level in a magnetic body;

• said apparatus comprising a primary winding, a secondary winding, and an adjustable impedance;
• said primary winding comprising one or more turns of conductive material;
• said primary winding conducting an alternating current;
• said primary winding being positioned relative to said magnetic body in such a way that said alternating current influences the induction level of said magnetic body;
• said secondary winding comprising one or more turns of conductive material;
• said secondary winding conducting a secondary current;
• said secondary winding being positioned relative to said magnetic body in such a way that said secondary current influences the induction level of said magnetic winding;
• said adjustable impedance having a suitable control means;
• said adjustable impedance being connected to said secondary winding;
• said control means controlling said adjustable impedance in such a manner so as to cause the induction level of said magnetic body to transition to said preferred induction level.

Apparatus for establishing a preferred induction level in a magnetic body;

• said apparatus comprising an electric energy source connected to a winding;
• said winding comprising one or more turns of conductive material;
• said winding being positioned relative to said magnetic body in such a way that said winding magnetically interacts with said magnetic body;
• said winding conducting a current;
• a change of induction level in said magnetic body being associated with an induced voltage across said winding;
• said electric energy source having suitable control means;
• said control means operating during a first phase to cause said electric energy source to cause said current to have such waveform, magnitude and duration so as to cause the induction level of said magnetic body to transition to a determinate induction level;
• said control means then operating during a second phase to cause said electric energy source to cause said induced voltage to have such waveform, magnitude and duration so that the value of the integral of said induced voltage over time is approximately equal to a volt-time value corresponding to a change in the induction level of said magnetic body from said determinate induction level to said preferred induction level, thereby causing the induction level of said magnetic body to transition from said determinate induction level to said preferred induction level.

Apparatus for establishing a preferred induction level in a magnetic body;

• said apparatus comprising an electric energy source connected to a winding;
• said winding comprising one or more turns of conductive material;
• said winding being positioned relative to said magnetic body in such a way that said winding magnetically interacts with said magnetic body;
• said electric energy source having suitable control means;
• said control means operating to cause said electric energy source to cause an alternating current to flow in said winding;
• said alternating current causing the induction level of said magnetic body to transition between opposite peak induction levels that are approximately equal in magnitude;
• said alternating current being associated with an alternating induced voltage across said winding;
• said alternating current and said alternating induced voltage having waveforms and magnitudes that are related by the properties of said magnetic body and said winding;
• the induction level of said magnetic body transitioning between opposite peak induction levels over the time period of a single half-cycle of said alternating induced voltage;
• the magnitude of said peak induction levels corresponding to a volt-time value approximately equal to one-half of the volt-time integral of a half-cycle of said alternating induced voltage;
• said control means operating to turn said electric energy source off at a point of time during a half-cycle of said alternating induced voltage such that the final induction level is near said preferred induction level.

Apparatus for providing a secondary current that is approximately proportional to a primary current;

• said apparatus comprising a current transformer and an electric energy source;
• said primary current flowing in a conductor configured as a primary winding of said current transformer;
• said electric energy source having suitable control means;
• said current transformer comprising a magnetic core and a secondary winding;
• said secondary current flowing in said secondary winding;
• a change of induction level in said magnetic core being associated with an induced voltage across said secondary winding;
• said electric energy source being connected to said secondary winding;
• said control means operating during a first mode to cause said electric energy source to produce an output having such waveform, magnitude and duration so as to cause the induction level of said magnetic core to transition to a preferred induction level;
• said control means then operating during a second mode to cause said electric energy source to provide a voltage that allows said secondary current to flow freely;
• said secondary current being approximately proportional to said primary current during said second mode.

A burden-reducing circuit for reducing the effective burden of a current transformer secondary circuit;

• said current transformer comprising a magnetic core and a secondary winding;
• a primary current flowing in a conductor configured as a primary winding of said current transformer;
• said secondary winding conducting a secondary current that is approximately proportional to said primary current;
• said secondary circuit comprising said secondary winding and any components connected to said secondary winding in such a way that said secondary current flows through said components;
• the flow of said secondary current being associated with an induced voltage across said secondary winding;
• said effective burden being approximately proportional to the magnitude of said induced voltage divided by the magnitude of said secondary current;
• said burden-reducing circuit comprising a voltage source connected in series with said secondary circuit;
• said voltage source having suitable control means;
• said control means operating to cause said voltage source to produce voltage that causes the magnitude of said induced voltage to be reduced, thereby reducing the effective burden of said secondary circuit.