On 12/21/2015 02:48 PM, andy pugh wrote: >> Where did you get the filter from? > search eBay for "Rasmi filter" and find one with the right number of > phases and current rating for your system. > > The suggestion from Bertho sounded to be worth a try too.
Yes, to expand slightly with all the filters being installed... You must ensure that all mains power input is in phase when it goes through separate filters (see below). Mains filters use T and Pi constructs where a (capacitively coupled) common goes to earth. If the filters are not connected with the phase-polarity in mind, then you will have an earth point that will conduct current, due to the phase-shift between the filters. The same happens when you use transformers. The capacitive coupling in your system may induce (large) currents if the power lines are not entirely in phase. The classic example is the computer with a printer. Touching the computer and the printer-cable (when they are not connected) can have a differential between them, and you get zapped. This happens when the devices are not on the common earth. However, connecting the earth will mean that there is an induced current in the earth between the devices, which still may wreak havoc. The "wisdom" people said in that case was: "put the plug in reversed". That simple swapping of phase and neutral often solves this particular common-mode problem because it will put both devices in phase. Now, using multiple mains-filters can be a huge problem because the common point (earth) of these filters may still be off due to load imbalances (cos(phi) differences) and therefore carry current. The best way to handle mains noise is to use one mains-filter, which must be rated for the total load. Internal wiring and loads should be carefully planned to prevent local phase-imbalances. Most local noise sources are (relatively) high-frequency and are dampened with shielding and ferrites on the wires. -- Greetings Bertho (disclaimers are disclaimed) ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
