I'll try to describe. Unfortunately, I can't include pictures or plots.
Product: Indoor Climate Central * 3-phase 400V/16A system (L3,L2,L1,N,PE) * 2 pcs 1-phase fans 500W (L1-N, L3-N) * 1 pcs touch panel / control module (L3-N) -> separate modul * Heating elements 2x2200W (L1,L2,L3) 3 pcs Schaffner FN2030-10-06 inserted on the power lines to the fans and touch panel / control module. >From the 3-phase inlet terminals and to the filter positions for the fans, the internal cable lengths are approximate 1 meter. The cable length from the terminals and to the touch panel / control module is appox. 2 meters. A 3-phace Schaffner filter (right by the terminals blocks), is considered to solve the conducted emission problem, but it is much more expensive than 3 x 1-phase filters. Initial measurements (no filters) showed noise around 3MHz (62dBuV QP and 44dBuV AVG). In addition, several spikes as 375kHz, 500kHz, 625kHz . with the measured values at 625kHz like 52dBuV peak, 51dBuV QP and 47dBuV AVG. With all filters inserted, the levels at 3MHz increase by 4-5 dB. Comparing measurements as no filters vs. filters to the fans only, the spectrum looks almost equal, when measuring at the N-phase. It seams that N-phase noise is higher than L1, L2, and L3 noise. Is the grounding good enough through the EUT and where the filters are connected? Do the long cable lengths (1-2 meters) pick up noise? The separate module, what about that ground connection to the main part? Correct type of filter? .. BR Amund -----Opprinnelig melding----- Fra: Amund Westin Sendt: 28. juni 2020 10:59 Til: EMC PSTC <[email protected]> Emne: Conducted emission - AC line filters makes it worse A 3-phase product has three internal AC driven devices. The product fails on Conducted emission. When connecting AC filters to each internal AC driven devices, the emission gets even worse. Any clue about this phenomena? Is it some kind of impedance mismatch which derate the filters performance? BR Amund - ---------------------------------------------------------------- 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 <[email protected]> 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 <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
