Newly UL- and Semko-approved is the dc and ac single line Feedthru filters from Spectrum Control Inc. (www.spectrumcontrol.com). Rated at 10-300A and intended for 0-400 Hz applications, these filters have C and Pi configurations with the dc models coming with Class Y4 capacitors while the ac models offer Class Y2 or Class Y4 capacitors. In addition, the bolt-in style with D-shaped bushing make installation easy.
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