The effect of using isolation transformers to supply small nonlinear loads

Abstract

It is well known that between other non-linear loads the IT and office equipment or measuring equipment are important sources of current harmonics. There are particular cases when equipment of this type are supplied through isolation transformers such as equipment dedicated for interface between a high voltage laboratory and its control room or medical equipment. In the first step it was analyzed the influence of voltage level upon current harmonic content in the case of desktop computers and cathode ray tube monitors directly connected to the network. The main parameters were recorded using a professional power quality analyzer. The effect of an isolation transformer used to supply the same consumers was then evaluated. In particular situations, the use of isolation transformer diminishes the current harmonics injected in the supply network.