On 05/14/2015 09:38 AM, Rick Lair wrote: > I have been following this thread somewhat, and have a question, > > What is the difference between a line reactor and emi input filter? A line reactor may be designed to reduce the 3rd harmonic produced by typical rectifier/capacitor 3-phase loads, and not worry much about higher harmonics. An EMI filter may not do anything for 3rd harmonic, but will be optimized to suppress conducted emissions on anything above a few hudred KHz. > We have a AD GS3 40hp drive in our turning center, and have the same > noise problems with the drive, and I am not sure which one to buy, or do > I need both? The drive schematic shows putting an emi filter on both > sides of the drive, would that help as well? Yes, the output side of the VFD is radiating at least as much, if not more, EMI than the input. > At $272 bucks a piece, I > don't want to throw money away, but I do want to get this put to bed, we > have been dealing with it for 2 years now, and I am getting tired of it. > > You may not need a $272 unit, although for 130 A line current (assuming 240 V, half that for 480 V) they will be a bit expensive. There are shielded cables for VFD to motor connections that are supposed to help.
Exactly what is being affected by the EMI? The control itself, or other gear in the plant? If the control of that machine is being affected, then it could be either, or both. if other plant equipment, then if the VFD is in a cabinet directly on the machine, then it sounds mostly like it is coupling through the input to the VFD, so I'd put the money at the input side first. Also, make sure the machine frame is securely grounded to the electrical panel ground. EMI return currents will flow through the ground. if the machine has a plugged-in power cord (Hubbel twist-lock style) then maybe run an additional ground to the outlet box. (Hmmm, 40 Hp machines won't likely be plugged in, even at 480.) You can get into trouble putting EMI filters on the output of the VFD, as this can cause excessive currents that can damage either the filter or the VFD. So, for the output side, use ONLY a filter recommended by the VFD maker. On the input side, you can use any filter that can handle the current draw, so you are not restricted by the VFD maker's recommendations. Jon ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
