Background: I have been installing a recently manufactured 230 Vac 5.5 kW pure sine non-isolated solar invertor whose design exploits the PV array input operating in the same power domain as the AC mains output, i.e. no isolating transformers. Noticing that my medium wave and long wave reception was now no longer possible due to the loud hum received right through the bands, I hung an oscilloscope on the mains wiring and noticed a 300 Vpp 50 Hz square wave with sharp edges (around 1-5 us order) superimposed (common mode) upon the AC mains output. The AC mains itself is otherwise a well formed near sinusoidal 50 Hz waveform with only minor distortion at cross-over.
Not wishing to cause nuisance interference to myself or others, I read the installation manual from cover to cover for guidance on EMC but found nothing and so began to try and understand how the issue might be resolved. Appreciating that the superimposed waveform might be influenced by the parasitic capacitance of the PV array relative to ground, I measured the parasitic capacitance as approximately 23 nF (this was not surprising in view of the length of underground cabling and PV array size). I then set to introduce Schaffner FN2010-30-08 filters into both the PV array input and AC mains output of the invertor but with no significant success. I am currently theorising that the level of the emission is so high that the common mode filtering inductor of this filter type is saturating. Question: Is it widely recognised that this type of invertor design is associated with high levels of EMC emissions? If so, on what basis might EMC compliance be claimed for such a unit? Perhaps there are specialist EMC filters targeted at this kind of invertor design. Phil EMC Engineer Leonardo UK Ltd Registered Office: 1 Eagle Place, St James’s, London SW1Y 6AF A company registered in England & Wales. Company no. 02426132 ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
