Analysis of the harmonic composition of current in the zero-working wire at the input of the load node with the prevailing non-linear power consumers

Due to the extensive use of nonlinear power consumers, there is currently an urgent problem of high harmonic content in power supply networks. The paper provides experimental investigations and a study of the nature of the change in the main harmonic components of the current in the neutral working wire of a three-phase four-wire network with a voltage of 0.38 kV. The purpose of this study is to compare the load readings on the amplitude-phase-frequency characteristics of the current in the neutral working wire of the 0.38 kV network with the linear and non-linear load. To study the effect of load changes on the amplitude-phase-frequency characteristics of currents in the linear and zero working wires at the input of the load node, measurements were carried out by certified electrical measuring instruments. The analysis of the results obtained for the load node whose power was formed mainly by a lighting system with fluorescent and LED lamps and a system of office electrical receivers (computers, copiers, printers, scanners, etc.) was performed. It can be concluded that a current comparable to the currents of the linear wires of the network flows from the load node with the predominant nonlinear power receivers through the zero-working wire. At the same time, in the zero-working wire of the network, the third harmonic currents prevail over the main frequency currents.