This paper presents a method for the detection of series arc faults in electrical circuits, which has been developed starting from an experimental characterization of the arc fault phenomenon and an arcing current study in several test conditions. Starting from this, the authors have found that is it possible to suitably detect arc faults by means of a high-resolution low-frequency harmonic analysis of current signal, based on chirp zeta transform, and a proper set of indicators. The proposed method effectiveness is shown by means of experimental tests, which were carried in both arcing and nonarcing conditions and in the presence of different loads, chosen according to the UL 1699 standard requirements.

Power quality instrumentation requires accurate fundamental frequency estimation and signal synchronization, even in the presence of both stationary and transient disturbances. In this paper, the authors present a synchronization technique for power quality instruments based on a single-phase software phase-locked loop (PLL), which is able to perform the synchronization, even in the presence of such disturbances. Moreover, PLL is able to detect the occurrence of a transient disturbance. To evaluate if and how the synchronization technique is adversely affected by the application of stationary and transient disturbing influences, appropriate testing conditions have been developed, taking into account the requirements of the in-force standards and the presence of the voltage transducer.

In this paper, a new approach is proposed for the detection of harmonic sources in polluted power systems. It is a single- point strategy, based on a comparison among different "nonactive" power quantities proposed in literature that, in the same working conditions, assume different values at the same metering section. Some simulations tests were carried out on a standard IEEE test system proposed by other authors as a benchmark system for the analysis of multipoint measurement techniques for harmonic pollution monitoring. The obtained results show that the proposed single-point approach is in agreement with other strategies already proposed in the literature and can provide useful indications for the detection of the dominant harmonic source upstream or downstream the metering section also in some critical cases.