Performance Enhancement of Rogowski Coil Through an Additive Manufacturing Approach

Abstract

The Rogowski coils, along with the amperometric clamps, are probably the most widespread current transducer when measurements must be performed on electrical circuits and/or systems that cannot be interrupted. Thanks to their flexible shape and a suitable closing mechanism, they can be easily installed around the primary conductor without interrupting the electric current that must be measured. Although their operating principle is very simple, the practical realization is far from the transducer model and, therefore, particular attention must be paid to geometry, orientation and positioning with respect to the primary conductor in order to reduce the uncertainty associated with measurement. To overcome this problem, the authors propose hereinafter a coil support realized in additive manufacturing technology capable of granting that (i) the Rogowski coil maintains a circular shape, (ii) the primary conductor passes in the coil center and (iii) the primary conductor is orthogonal to the surface defined by the coil itself. Thanks to 3D printing approach, the support can easily be adapted to coils of different circumference by simply rescaling its dimensions during the printing phase.To assess the performance improvement brought by the proposed support, several tests have been conducted in operating conditions involving different values of nominal current; in particular, the difference between the nominal current and that measured by the coil mounted on the proposed support was measured and compared with that associated with the coil characterized by one or more of the considered problems. The results obtained showed limited and systematic differences, which can then be compensated through a preliminary calibration operation in the laboratory.