Behavior of fast variable loads at the connection to the power supplying source

The paper deals with problems related to non-sinusoidal regimes introduced in the supplying network by a laptop and respectively by a set of laptops connected in various configurations. The three-phase voltage(s) and current(s) were acquired with an original data acquisition system with a sampling frequency of 19,200 Hz. Harmonic decompositions up to an order of 192 (corresponding to a frequency of 9,600 Hz) are presented. The influence of a single laptop over the supplying network is analyzed firstly. Several connection configurations are studied along different phases of the three-phase supplying system. The non-symmetries associated to different configurations are discussed. For the low voltage supplying a significant current along the null wire was revealed. An analysis of powers is performed, based on the voltages and currents harmonic decompositions. The capacitive character of the three-phase consumer is emphasized, along each phase and for the whole three-phase consumer respectively. The features of the studied regimes (significant deviations from the sinusoidal shape along with non-symmetries), and the influence that these regimes can have over the supplying network are approached. An analysis is also performed considering cases in which some of the laptops perform heavy computational tasks. The necessity to protect the supplying network against the influence of this type of consumers is emphasized, because the PQ standards are not obeyed for the analyzed cases.