Abstract: An apparatus, that is particularly advantageous for compensating for the earth's magnetic field at a fluxgate current sensor. The apparatus and method actively compensate for local anomalies and loop mismatch at local segments distributed around closed loops of ferromagnetic material in order to null out sources of error that arise in the presence of an external magnetic field. External flux nulling circuits null the external magnetic flux at each of a plurality of associated pairs of diagonally opposite segments of coaxial closed loop cores. Each flux nulling circuit has a pair of diagonally opposite segment sensing coils and a pair of diagonally opposite segment cancellation coils. A flux detecting circuit detects the net magnetic flux in associated, diagonally opposite segments. A negative feedback control circuit drives the segment cancellation coils with a current to drive the flux detected by the segment detecting circuit to a minimum.

Abstract: An integral meter and current transformer to measure single phase active and reactive energy, voltage and frequency in industrial, commercial and multi-family residential applications. The meter CT is the primary sensing element in a revenue metering system encompassing multiple meter CTs serially connected in groups in communication with data cores for collection and reporting of energy consumption. Numerous data cores may be networked to report to a central station which may be remotely interrogated over the network or dial up modem connection. The meter CT utilizes a split-core transformer with substantially overlapping fingers. Disengaging split-core sections of the meter CT enables it to be easily installed around a loaded conductor without the interruption of power to the load.