I forgot to mention. There is a capacitance between motor cables and protective earth. Then the motor is driven by the VFD it is supplied with square wave voltages at high frequency and at each switching the capacitance is discharged or charged. As impedance at high frequency is far from zero in the power cables the ground will bounce around. If i think correctly both the protective and the rectified power ground will bounce around in opposite directions but I have never measured this.
The common mode impedance may be rised by adding a common mode inductur in the loop. Nicklas Karlsson On Thu, 14 May 2015 10:38:43 -0400 Rick Lair <[email protected]> wrote: > I have been following this thread somewhat, and have a question, > > What is the difference between a line reactor and emi input filter? > > 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? 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. > > Thanks > > Rick > > On 5/14/2015 9:53 AM, Dave Cole wrote: > >>> The Rasmi input filter > > Take it off and see what happens.... > > > > If that drive is screwing with your keyboard that is on the OUTSIDE of your > > control cabinet, imagine what kind of RF exposure is on the inside of your > > control cabinet! > > > > Those AD VFDs should also be sold as EMI test generators. ;-) > > > > Dave > > > > > > > > On 5/14/2015 8:53 AM, Tom Easterday wrote: > >> I spent some time with the spectrum analyzer but did’t have much luck in > >> isolating the sink for the noise. I just verified that my VFD does indeed > >> produce a large amount of noise between low kHz and about 10MHz! I did > >> some re-routing of wires and replaced some that weren’t shielded. I > >> ordered some ferrites for the VFD-motor wiring and my computer I/O > >> extension cabling which will be here in a couple days. > >> > >> However, I did find the source of the main problem! It was indeed my > >> keyboard. Not the USB wiring from keyboard to pc, but the keyboard ITSELF > >> is very sensitive to the noise created by the VFD. If I move the keyboard > >> to the very extreme end of it’s (rather long) usb cable the problem > >> disappears completely. 6” closer to the cabinet and noise reappears. > >> Apparently the noise is being interpreted as key presses by the keyboard > >> circuitry. I replaced the new water resistant Logitech keyboard with a > >> very old Apple keyboard I had lying around and no more random characters! > >> I also had a second problem where the VFD would shut down somewhat > >> randomly which I thought was related to this noise as well. That turned > >> out to be an over current condition at very low rpm. Tweaking some > >> settings fixed that. > >> > >> The Rasmi input filter, and various re-wiring and shielding I did was > >> probably not needed, but in the long run perhaps it will save me from > >> other problems. > >> > >> Thanks, for all the input, > >> -Tom > >> > >> > >> ------------------------------------------------------------------------------ > >> 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 > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > --- > > This email has been checked for viruses by Avast antivirus software. > > http://www.avast.com > > > > > > ------------------------------------------------------------------------------ > > 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 > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > -- > > Thanks > > > Rick Lair > Superior Roll & Turning LLC > 399 East Center Street > Petersburg MI, 49270 > PH: 734-279-1831 > FAX: 734-279-1166 > www.superiorroll.com > > > ------------------------------------------------------------------------------ > 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 > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
