Marco Landini

Magnetic-field transducer based on closed-loop operation of magnetic sensors

A high-sensitivity magnetic transducer able to sense magnetic fields from dc up to tens of kilohertz is analyzed in this paper. The system is based on a nulling field coil fed by a current on the basis of the residual field, sensed by a magnetic sensor (Hall or magnetoresistive) placed in the coil center. In this way, the coil current proportionally represents the external field component along the coil axis, and it can be easily converted in a voltage signal by a series resistor. Then, a one-axis Gauss meter can be readily obtained. The sensitivity and the bandwidth of the overall system are discussed by a transfer function analysis. A hardware prototype has been realized, and significant test results are shown by means of a reference magnetic-field-generation setup. Useful guidelines for the overall system design are given.

A magnetic field transducer based on closed-loop operation of magnetic sensors

A high sensitivity magnetic transducer able to sense magnetic fields from DC up to tens kHz is discussed in this paper. The system is based on a ing field coil fed by a current on the basis of the residual field, sensed by a magnetic sensor (Hall or magneto-resistive) placed in the coil center. In this way, the coil current proportionally represents the external field component along the coil axis, and it can be easily converted in a voltage signal by a series resistor. Then, a one-axis gauss meter can be readily obtained. The sensitivity and the bandwidth of the overall system are discussed by a transfer function analysis. A hardware prototype has been realized, and significant test results are shown by means of a reference magnetic field generation set-up. Useful guidelines for the overall system design are given in the paper.

A Simple Innovative Method to Calculate the Magnetic Field Generated by Twisted Three-Phase Power Cables

This paper firstly examines the consolidated analytical methodologies available in literature for the calculation of the magnetic field generated by a twisted three-phase conductor arrangement carrying balanced three-phase currents. Such literature methodologies consist of an exact analytical expression of the RMS magnetic induction given in the form of complicated Bessel-function series and of an approximation of such exact expression where only the first term of the series is considered. Subsequently, a simple innovative approximated formula for the RMS magnetic induction generated by twisted three-phase power cables is obtained by means of an heuristic procedure. This formula results a good approximation of the rigorous analytical one and at the same time is much more accurate than the approximated formula found in literature, as demonstrated by the case of a twisted three-phase power cable used for power distribution at the medium voltage level.

Simple calculation method of the magnetic field from double-circuit twisted three-phase cables as a tool for fault detection

This paper proposes a simple innovative formula for the calculation of the magnetic field generated by a single and a double circuit twisted three-phase power cable line. The formula results a good approximation of the rigorous analytical one and at the same time is much more accurate than the approximated formula found in literature, as demonstrated by the case of a twisted three-phase power cable used for power distribution at the medium voltage level. The effectiveness of this simple innovative formula is examined in the case of a double-circuit twisted three-phase power cable line following the ‘worst case’ approach and we propose an approximate expression for the total magnetic field generated by both twisted three-phase power cables that can be used as a diagnostic tool in fault detection algorithms, as the magnetic field can provide useful information on the phasors of the currents flowing through the conductors.

A smart measurement and evaluation system for the magnetic-field generated by multiple field sources in complex 3-D arrangements

This work deals with the experimentally-based evaluation of the total magnetic induction field B generated by multiple sources in complex three-dimensional arrangements, carried out on the basis of the measurement of the field components in a Cartesian coordinate system, Bx, By and Bz. Such a goal is achieved by means of an innovative measurement and evaluation system, that is proposed, described and validated in the paper. The ultimate goal is verifying that magnetic induction intensity is within the prescribed limits.

Smart measurement system for the assessment of magnetic fields generated by complex power systems

This paper presents the development of an innovative measurement system of magnetic fields. The instrument is smart as it is able to measure and postprocess the data to obtain the prediction of the maximum magnetic field. The description of the system and the data postprocessing theory are provided. Some results of the correlation obtained with the instrument are shown.

Innovative measurement and evaluation apparatus of magnetic field in complex arrangements of multiple field sources

An innovative measurement and evaluation system is proposed, described and validated in this paper for verifying that the magnetic induction intensity is within the prescribed limits. The total magnetic induction field B generated by multiple sources in complex three-dimensional arrangements is experimentally evaluated on the basis of the measurement of the field components in a three-dimensional Cartesian coordinate system.

Innovative calculation methods of the magnetic field from single and double-circuit twisted three-phase cables widely used in MV and LV installations

This paper proposes a simple innovative formula for the calculation of the magnetic field generated by a single and a double circuit twisted three-phase power cable line. The formula results a good approximation of the rigorous analytical one and at the same time is much more accurate than the approximated formula found in literature, as demonstrated by some cases of a twisted three-phase power cable used for power distribution at the medium voltage level. The effectiveness of this simple innovative formula is also examined in the case of a double-circuit twisted three-phase power cable line following the’ worst case’ approach and concluding at proposing an approximate expression for the total magnetic field generated by both twisted three-phase power cables.

MAGNETIC FIELD GENERATED BY DOUBLE-CIRCUIT TWISTED THREE-PHASE CABLE LINES

The evaluation of the magnetic field from double-circuit twisted three-phase power cable lines misses a sound and exhaustive theoretical and experimental treatment in the literature. This paper presents a rigorous approach to the calculation of the magnetic field from double-circuit twisted threephase cables, whereby the magnetic field generated by such cables is computed as the vector sum of the two individual fields generated by each twisted three-phase cable. This approach is validated by means of extensive measurements of the magnetic field from singleand double-circuit twisted three-phase power cables — provided by Italian utilities — identical to those installed in the field.