The Calibration of Loop Impedance Meters: a Proposal

In the electrical measurement practice, the measurements of the quantities related to the safety and preventive maintenance of the electrical distribution system are very important. Due to the potential risk caused by incorrect measurements, it is necessary to assess the status of the employed measurement system at all times and also assure the measurement traceability. This means calibrating the instrument periodically. When particular instruments like the loop impedance meters are taken into account, the calibration process presents some critical aspect. The reason mainly comes from the difficulty to define and develop a working standard of loop impedance with a proper uncertainty. In this paper, a simple method for the calibration of loop impedance meters is presented, based on a dedicated electric system that can be employed as a “reference” system, assessing a good level of the loop impedance value reproducibility. The design aspects of the system and its performance in terms of measurement uncertainty are also presented.