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Home Rectifier Transformers and Reactors Rectifiers with CapacitorInput Filters  
See also: SinglePhase Rectifiers, Rectifiers with ReactorInput Filters, Polyphase Rectifiers, CapacitorInput Filters  
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Rectifiers with CapacitorInput Filters
When the filter has no reactor intervening between rectifier and first capacitor, rectifier current is not continuous throughout each cycle and the rectified wave form changes. During the voltage peaks of each cycle, the capacitor charges and draws current from the rectifier. During the rest of the time, no current is drawn from the rectifier, and the capacitor discharges into the load.
Analysis of this chargedischarge action involves complicated Fourier series which require a long time to calculate.^{(1)} Satisfactory voltage and current values have been obtained from experimental measurements by Schade ^{(2)} and are shown in Figs. 50, 51, and 52 for singlephase halfwave and fullwave rectifiers.
In these figures R_{s} is the rectifier series resistance, including the transformer resistance. Results accurate to within 5 per cent are obtained if the rectifier resistance corresponding to peak currentis used in finding R_{s}. The process is cutandtry, becausedepends on R_{s}, and vice versa, but two trials usually suffice. Resistance is in ohms, capacitance is in farads, and ω is 2π times the supply frequency. Threephase rectifiers are rarely capacitorinput because of their larger power. In Fig. 52 the peak current indicates whether the peak current of a given tube is exceeded, and the rms current determines the transformer secondary heating. The va ratings are greater, but ratios of primary to secondary va ratings given in Table VII hold for capacitorinput transformers also.


Home Rectifier Transformers and Reactors Rectifiers with CapacitorInput Filters 