A current sensor arrangement for measuring an effective primary current in a primary conductor having a magnetic core for magnetic coupling of the primary conductor to a secondary conductor and a controlled voltage source connected to the secondary conductor and configured to apply a voltage with adjustable polarity to the secondary conductor so that a secondary current passes through the secondary conductor. A measurement and control unit is coupled to the secondary conductor and configured to generate a measuring signal that represents the secondary current, to continuously detect the occurrence of magnetic saturation in the core, and to reverse the polarity of the voltage upon the detection thereof in order to reverse magnetization of the core. Furthermore, the measurement and control unit is configured to evaluate a spectrum of the measuring signal and determine a frequency of a current passing through the primary conductor based on the spectrum.

A first coil is wound around a first core, and have one end that is connected to ground and the other end that is connected to one end of a second coil. The second coil is wound around a second core, and has the one end that is connected to the first coil, and the other end that is connected to an excitation unit via a current-limiting resistor. A magnetic flux is generated in the first core by an excitation signal outputted from the excitation unit. Induced electromotive force is generated in the conductor due to the magnetic flux generated in the first core. The direction of the magnetic flux generated in the second core is opposite to the direction of the magnetic flux generated in the first core, and the induced electromotive forces of them generated in the conductor are cancelled each other out.

When a through hole is formed in a primary conductor, a measurement target current partially becomes a bypass current that flows around the through hole. Only a magnetic field component in the X-axis direction is generated from the current that flows through a portion without the influence of the through hole. However, the bypass current generates a magnetic field component in the Y-axis direction at the tilt portion. A magnetic detection element having a magnetic field detection sensitivity only in the Y-axis direction is installed near the through hole such that the magnetic field detection direction is set in the Y-axis direction, thereby detecting the magnetic field component and measuring the current amount without the influence of a neighboring current.

A method for measuring current includes passing a DC current through the primary side of a transformer and driving the secondary side of the transformer with an AC voltage, wherein the current in the secondary side of the transformer reaches a plateau. The current in the secondary side of the transformer is measured during the plateau, wherein the measured current is proportional to the DC current.

A method for measuring current includes passing a DC current through the primary side of a transformer and driving the secondary side of the transformer with an AC voltage, wherein the current in the secondary side of the transformer reaches a plateau. The current in the secondary side of the transformer is measured during the plateau, wherein the measured current is proportional to the DC current.

A fast-response direct-current current transformer based on multi-sensor fusion is provided and includes: a magnetic modulator, a current correction module, an excitation transformer, an alternating current detection and filtering circuit, a phase-sensitive demodulation and filtering system, a PI controller, and a power amplifier. The current correction module measures a primary current and obtain a feed-forward signal, outputs a false balance state configured to control a magnetic core to quickly exit or avoid entering magnetic saturation after amplifying the feed-forward signal and a PI control signal, and keeps output of the magnetic modulator stable. The magnetic modulator and Hall current sensors are fused in the disclosure, such that the possibility of failure due to a false balance problem caused by saturation of a magnetic core is reduced. After the false balance is generated the magnetic core may be controlled to quickly exit a magnetic saturation state through a feed-forward output current.

The line power and neutral conductors for a circuit interrupter such as a miniature circuit breaker, using ground fault sensing via a current transformer, are arranged as a rigid conductor formed from a flat plate and surrounding and holding an insulated flexible conductor when passing through the Ground Fault Interrupter current transformer. The rigid conductor can provide a shaped current path to maximize the effectiveness of the current transformer.

The line power and neutral conductors for a circuit interrupter such as a miniature circuit breaker, using ground fault sensing via a current transformer, are arranged as a rigid conductor formed from a flat plate and surrounding and holding an insulated flexible conductor when passing through the Ground Fault Interrupter current transformer. The rigid conductor can provide a shaped current path to maximize the effectiveness of the current transformer.

A flux gate current sensor includes a magnetic core, a measurement winding, an excitation circuit arranged to generate a digital excitation signal, an acquisition circuit arranged to acquire an analog measurement voltage from the terminals of the measurement winding and to produce a digital measurement signal, a demagnetization servocontrol circuit arranged to use the digital measurement signal to produce a digital demagnetization signal for compensating magnetic flux produced by the current that is to be measured, a summing circuit arranged to sum the digital excitation signal and the digital demagnetization signal so as to obtain a digital injection signal, and an injection circuit arranged to produce an analog excitation current from the digital injection signal and to inject the analog excitation current into the measurement winding.

A flux gate current sensor includes a magnetic core, a measurement winding, an excitation circuit arranged to generate a digital excitation signal, an acquisition circuit arranged to acquire an analog measurement voltage from the terminals of the measurement winding and to produce a digital measurement signal, a demagnetization servocontrol circuit arranged to use the digital measurement signal to produce a digital demagnetization signal for compensating magnetic flux produced by the current that is to be measured, a summing circuit arranged to sum the digital excitation signal and the digital demagnetization signal so as to obtain a digital injection signal, and an injection circuit arranged to produce an analog excitation current from the digital injection signal and to inject the analog excitation current into the measurement winding.