Device for measuring at least one electrical variable of a current intended to flow in an electric apparatus, the electric apparatus comprising at least one connection terminal, each connection terminal being designed to be electrically connected to the end of a corresponding electric conductor, the device comprising at least one current sensor, each current sensor being configured for measuring the current flowing in a corresponding electric conductor. The device further comprises at least one electrically conductive spacer, each spacer being configured for being interposed between a respective connection terminal and the end of a corresponding electric conductor, and wherein each current sensor is further positioned around a respective spacer, to measure the current flowing through said spacer, between the electric conductor and the corresponding connection terminal.

There is provided a neutral pole transformer module for a circuit breaker capable of minimizing an influence of external noise, detecting a neutral pole current at low manufacturing cost, and detecting a neutral pole current without modifying a configuration of an existing overcurrent relay or without installing an additional component in the existing overcurrent relay. The neutral pole transformer module for a circuit breaker comprises a ZCT configured to allow a transmission line of a neutral pole detection current output from the current transformer to pass therethrough and to provide a secondary output current signal obtained by reducing the neutral pole detection current in a predetermined ratio; a printed circuit board configured to convert the secondary output current signal into a voltage signal, and to differentiate the converted voltage signal and output the same; and an enclosure formed of an electrical insulator and enclosing the ZCT and the PCB.

The present invention provides a careless contactless current measurement system comprising a conductive means through which a current can flow and a current sensor for calculating information about the current flowing through the conductive means, wherein: a relative position between at least a part of the conductive means and at least a part of the current sensor is fixed; the current sensor obtains a magnetic flux generated by the current flowing through the conductive means and transmitted through a nonmagnetic material, and outputs information about the current flowing through the conductive means in a wired or wireless manner Because such characteristics change only the shape of the conductive means around the magnetic flux measuring means without using a magnetic core, the amount of a magnetic flux passing through the magnetic flux measuring means is increased, thereby improving a signal-to-noise ratio (SNR) of the magnetic flux measuring means.

A voltage/current probe includes: a circuit board; a first inductor that is located on the circuit board, that is wound in a first direction, and that includes: a first end connected to a first output conductor; and a second end; a second inductor that is located on the circuit board, that is wound in a second direction that is opposite the first direction, and that includes: a third end that is connected to a second output conductor; and a fourth end that is connected to the second end of the first inductor and to a third output conductor.

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 three-phase power meter can monitor power on both 3-wire and 4-wire power lines. The power meter measures at least two voltages between phase conductors of the power line, and at least one voltage between a phase conductor and a neutral conductor of the power line when the neutral conductor is available. Using at least some of the measured voltages, the power meter can then operate in a first mode when coupled to a 3-wire power line to determine power on the power line based on the measured voltages, or operate in a second mode when coupled to a 4-wire power line to determine power on the power line based on the measured voltages.

A method for manufacturing a short-circuit protection device, including producing, on a first face of a first substrate, a plurality of first electrically conductive segments; producing, on the first face, a plurality of electrically conductive pads each being in mechanical and electrical contact, through the base thereof, with a single corresponding first segment; producing, on a second face of a second substrate, a plurality of second electrically conductive segments; placing the first face and the second face opposite to each other, to bring a free end of each pad into mechanical and electrical contact with a single corresponding second segment, such that the first segments, the second segments and the pads form a coil.

A Rogowski coil is used for determining the magnitude of the electrical current of a conductor of a low-voltage AC circuit, which outputs an analogue voltage which is equivalent to the magnitude of the electrical current of the conductor. The Rogowski coil is connected to an analogue integrator, which is followed by an analogue-digital converter, which converts the integrated analogue voltage into a digital signal which is further processed by a microprocessor in such a way that the phase shift generated by the Rogowski coil and the components connected downstream of the Rogowski coil is compensated such that there are in-phase current values for the detection of error situations in order to protect the low-voltage AC circuit, in particular for a low-voltage power switch or an arc fault detection unit.

A current sensor includes a lead frame having a plurality of leads, at least two of which form a current conductor configured to carry a current that generates a magnetic field and a substrate having first and second opposing surfaces, the first surface proximate to said current conductor and the second surface distal from the current conductor. A first magnetic field transducer is disposed on the substrate and a first coil is disposed on the substrate adjacent to the first magnetic field transducer, wherein the first magnetic field transducer and the first coil are positioned on a first side of the current conductor. A second magnetic field transducer is disposed on the substrate and a second coil is disposed on the substrate adjacent to the second magnetic field transducer, wherein the second magnetic field transducer and the second coil are positioned on a second side of the current conductor.

A measuring unit for simultaneous measurement of two current values and two voltage values of a power line with three high-voltage conductors includes: three two-pole electrical interconnections, each interconnection being configured to be connected between two separated ends a high-voltage conductors; a first and second current sensor, configured and arranged to measure a current through the first interconnection and through the third interconnection respectively; and a first and second voltage sensor, configured and arranged to measure a voltage between the first and second interconnection and between the second and third interconnection. The measurement of the two current values and the two voltage values is at a floating potential. This measuring unit may be installed directly on all three phases, of a substation for example, with its own internal power source and with no ground connection. Such features are important for power systems with high penetration of variable renewable energy resources such as solar PV or wind.