Wave form distortion and its effects on electrical apparatus

The present rule of the Institute in regard to wave form is not satisfactory, as it does not sufficiently penalize the higher frequency harmonics. Deviation of the wave shape from the sine form is considered, and the effect on the current wave form in connection with various kinds of circuits, such as resistance, inductance and capacity. Conditions occurring with two differently shaped e. m. f. wave forms in parallel are also considered, and the resultant effect on the current wave. It is shown how, in some cases, very great current wave distortion may occur, or excessively large local currents may flow between synchronous machines, due to difference in e.m.f. wave shape. Several examples are given of excessive current and e.m.f. wave distortion. Errors in power factor meters and other instruments due to wave shape are discussed.