The applications of static converters constructed by solid state semiconductor components for DC and ac motor drives are increasing dramatically at all customer levels. Though static power converter drives provide higher efficiencies, better speed/torque control, and more maintenance free operation than conventional drives, they brought some detrimental effects on the quality of the ac utility power system. In particular when static converters form a significant proportion of the power system loads [1-6]. This paper presents four issues on their impacts on power supply system. Firstly the cause and the effects of line notching and harmonic distortions on power systems. The paper also discusses the formulation, review and modelling of line notching phenomenon. Experimental results of a laboratory experiment and a computer simulation model have been developed to verify the notching voltage formulation. Finally some recommendations are made as how these adverse effects can be mitigated.