Analysis of the behaviour of fusing systems in the presence of nonlinear loads

This paper describes the behaviour of fusing systems in the presence of both nonlinear single phase and three phase loads. Such loads, producing harmonic currents, yield high peak currents. Specifically, IT-equipment where the nonlinearity is caused by the bridge rectifier of the switching power supply and variable speed drives are considered. The paper presents the study of the influence of the waveform of the neutral conductor current on the behaviour of the fusing system. Using a programmable power source, an arbitrary voltage waveform is generated. Each phase is loaded by a variable number of resistors. For different set ups of the power source and load conditions, the phase currents are analysed using on-line monitoring. The ratio of the phase RMS to peak current on the behaviour of fusing systems is analysed.