Ken KF Lee’s research while affiliated with Lee's Pharmaceutical (Hong Kong) Limited and other places

Due to the growing use of non-linear load equipment and new technologies in buildings, harmonic currents generated in distribution systems pose a new problem for electrical engineers. This is a serious problem when power quality is a prime concern. The problem is due to some non-linear loads showing different current waveforms when supplied by a distorted voltage. This paper summarises the results of a case study survey in an office building with a large number of connected computers, a major source of harmonics. The scope of work included site measurement and analyses. The characteristics and effects of harmonic distortion of load current and voltages on distribution systems are discussed. It was found that on most occasions, careful planning and design can minimise the risk of harmonic-related losses in electrical systems. However, this does not always guarantee satisfaction. A bank of capacitors may be used to improve power factors in electrical systems, though in some cases such a bank may make the situation worse. An alternative is filters, but the position of filters is also crucial. Based on the case study, the paper discusses alternatives and provides some practical solutions to the problem of harmonics in office buildings.