Described herein is a method and apparatus for measuring the potential on a modern shielded high-voltage cable such as those used in medium-voltage distribution networks. A capacitive sensor arrangement (100) is constructed on a cable (110) using pre-existing structures (114, 116, 118, 120) within the cable (110). The use of implicit guarding methods is also described that allows the use of the semiconductor layer (116) present in modern cable design to be retained and to form part of the capacitive sensor arrangement (100). Performance of the sensor arrangement (100) can also be improved using temperature compensation techniques.

A three-phase alternating current mains has capacitor bushings that each have a conductor connected with one of the mains lines of the alternating current mains and an electrically conductive lining surrounding the conductor. These bushings are monitored by first determining an upper capacitance and a lower capacitance for each bushing and then detecting a measured voltage between the respective lining and a ground potential at each capacitor bushing. An actual capacitance for each capacitor bushing is calculated that depends on the respective measured voltage and the respective lower capacitance as well as on the measured voltage, the lower capacitance, and the upper capacitance of one of the other capacitor bushings. For each capacitor bushing the respective upper capacitance is compared with the respective actual capacitance and a monitoring signal is generated that is dependent on the results of the capacitance comparison.

A three-phase alternating current mains has capacitor bushings that each have a conductor connected with one of the mains lines of the alternating current mains and an electrically conductive lining surrounding the conductor. These bushings are monitored by first determining an upper capacitance and a lower capacitance for each bushing and then detecting a measured voltage between the respective lining and a ground potential at each capacitor bushing. An actual capacitance for each capacitor bushing is calculated that depends on the respective measured voltage and the respective lower capacitance as well as on the measured voltage, the lower capacitance, and the upper capacitance of one of the other capacitor bushings. For each capacitor bushing the respective upper capacitance is compared with the respective actual capacitance and a monitoring signal is generated that is dependent on the results of the capacitance comparison.

Determining the inductance L of an electrical component includes a high current pulse being generated and conducted through the electrical component. The electronic component is arranged in an electrical resonant circuit, in series with a reference component and with at least one capacitor. The resonant circuit is excited to oscillate by the high current pulse. Electrical properties of the electrical component are measured for a measuring duration, and the inductance L of the electrical component is determined from the measured electrical properties. A voltage drop U across the electrical component and a reference voltage drop U.sub.R across the reference component having a known reference inductance L.sub.R is measured. The inductance L of the electrical component is calculated as a product of the reference inductance L.sub.R with a proportionality factor, which is dependent on the measured voltage drop U and the measured reference voltage drop U.sub.R.

Determining the inductance L of an electrical component includes a high current pulse being generated and conducted through the electrical component. The electronic component is arranged in an electrical resonant circuit, in series with a reference component and with at least one capacitor. The resonant circuit is excited to oscillate by the high current pulse. Electrical properties of the electrical component are measured for a measuring duration, and the inductance L of the electrical component is determined from the measured electrical properties. A voltage drop U across the electrical component and a reference voltage drop U.sub.R across the reference component having a known reference inductance L.sub.R is measured. The inductance L of the electrical component is calculated as a product of the reference inductance L.sub.R with a proportionality factor, which is dependent on the measured voltage drop U and the measured reference voltage drop U.sub.R.

A sensor for a separable connector includes a plug body, one or more high voltage capacitors, one or more low voltage capacitors, and a low voltage connection. The plug body includes an insulating resin. The plug body can be inserted into the separable connector to encase a high voltage conductor disposed in the separable connector. The one or more high voltage capacitors are encased by the insulating resin and can be electrically coupled to the separable connector at a first end portion when the plug body is inserted. The one or more low to voltage capacitors are electrically coupled in series to the one or more high voltage capacitors to form a capacitive voltage divider. The low voltage connection provides a low voltage signal corresponding to a high voltage signal present in the separable connector. Signal conditioning electronics or a memory may also be included.

A sensor for a separable connector includes a plug body, one or more high voltage capacitors, one or more low voltage capacitors, and a low voltage connection. The plug body includes an insulating resin. The plug body can be inserted into the separable connector to encase a high voltage conductor disposed in the separable connector. The one or more high voltage capacitors are encased by the insulating resin and can be electrically coupled to the separable connector at a first end portion when the plug body is inserted. The one or more low to voltage capacitors are electrically coupled in series to the one or more high voltage capacitors to form a capacitive voltage divider. The low voltage connection provides a low voltage signal corresponding to a high voltage signal present in the separable connector. Signal conditioning electronics or a memory may also be included.

A sensor for detecting voltage of a power cable includes a housing configured to be coupled around at least a portion of the power cable. A first conductive element supported by the housing is configured to be electrically coupled to the power cable when the housing is coupled around at least a portion of the power cable. A first capacitive element supported by the housing is electrically interconnected with the first conductive element. A second capacitive element supported by the housing is electrically interconnected with the first conductive element. A processor determines a cable capacitance of the power cable based upon alternatively sensing an electrical characteristic (i) the first capacitive element and the second capacitive element and (ii) the first capacitive element without the second capacitive element. The sensor determines the voltage of the power cable based upon the determined cable capacitance.

A sensor for detecting voltage of a power cable includes a housing configured to be coupled around at least a portion of the power cable. A first conductive element supported by the housing is configured to be electrically coupled to the power cable when the housing is coupled around at least a portion of the power cable. A first capacitive element supported by the housing is electrically interconnected with the first conductive element. A second capacitive element supported by the housing is electrically interconnected with the first conductive element. A processor determines a cable capacitance of the power cable based upon alternatively sensing an electrical characteristic (i) the first capacitive element and the second capacitive element and (ii) the first capacitive element without the second capacitive element. The sensor determines the voltage of the power cable based upon the determined cable capacitance.

Improved power line management is provided by the systems and methods disclosed herein that accurately measures voltage in a power distribution system. In various embodiments, the system may include one or more sensor units, each coupled to the power lines using a capacitive or resistive voltage divider to yield a voltage at a sensor unit that is within a measurable range. In one aspect, this voltage may also be used to power the sensor unit and/or other devices coupled to it.