The paper is devoted to the research of power quality in the systems including electrical equipment of nonlinear type. Quantitative and qualitative analysis has been carried out in order to assess whether a UPS system may reduce higher harmonic components that are introduced to supply networks in result of connection of a nonlinear load. Moreover, interaction of the disturbances arising in the network with electrical equipment connected to UPS has been tested, with a view to check possible elimination of the interaction by means of a guaranteed supply system.



The parts, devices, and electrical systems are commonly used in all domains of human activity, in private and professional circumstances (the industry, administration, science, the whole sphere of services, etc.). It should be noticed that any electrical device is endangered to be disturbed and, in result, may fail to operate properly or to be damaged.

Any current or voltage bearing part is a source of electromagnetic interaction. At the same time in the elements subject to the electromagnetic interaction the electric signals (i.e. voltage and current) are generated. They may be useful (i.e. generated intentionally with a view to achieve some determined effect) or unwanted, leading to disturbance of proper operation or to damage of the parts they are generated in.

Taking into account common use of electric equipment and frequent occurrence and interaction of many various devices in the vicinity, the need to ensure proper and undisturbed operation of all these elements becomes particularly important. In order to achieve this, the procedures related to electromagnetic compatibility define acceptable levels of the interactions for every electric and electronic element, with respect to emissivity (introduction to the environment) and to immunity (i.e. delimited sensitivity to the disturbances), in order to attain harmonious operation of these devices in the environment [1-8].

The electric, electronic, and computer equipment is permanently modernized during its usage, thus reaching higher and higher level of technological development. Power input to these elements is often of discretized, pulse character, and, therefore, such an element consumes a distorted current. This, in turn, results in interaction and introduction of higher harmonic components to the network. On the other hand, correct operation of electrical equipment depends, to large extent, on the supply voltage quality (reduced occurrence of high harmonic components, voltage dip or loss of voltage, overvoltage). Operation quality and correctness becomes particularly important in case of strategic objects, related to information processing or realization of the processes the break of which is conducive to large economic loss [1-8].

The paper is focused on the research of electric power quality in the systems of nonlinear character. Comparison of the contents of voltage and current harmonic components at input and output of an emergency power supply is made, spectral distribution of the distorted signal is presented. Quantitative and qualitative analysis was carried out, in order to assess the effect of the guaranteed supply system UPS EVER Superline on reduction of the disturbances in the form of higher harmonic components introduced by nonlinear electrical equipment into the supply network, and on possible elimination of transmission of network disturbances in the form of overvoltage, voltage dip or loss of voltage to the equipment supplied through the UPS.

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dr inż. Karol Bednarek - EVER Sp. z o.o
dr inż. Leszek Kasprzyk - Poznań University of Technology