Kirk Wallace wrote: > I miss-typed earlier, the three "extra" wires do not connect at the motor > end. They are bundled together in the connector box, but do not Ohm out. > So I have three motor wires U, V, W and three that connect to nothing. >
It sounds like you have VFD cable. There are three main conductors and three grounds. That construction is chosen to keep stray capacitance and inductance balanced and symmetrical. Regardless of any "star grounding" you may be doing, the ground conductor(s) in any cable running from a VFD to a motor should be connected to the motor frame and to the ground terminal(s) on the VFD. As Peter Wallace pointed out, winding-to-frame capacitance in the motor _will_ inject currents into the motor frame. A proper ground conductor in the same cable or conduit as the motor leads allows those currents to return directly to the drive. If you don't provide a nice direct ground, the currents will find some other path, probably one you won't like. Regards, John Kasunich ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
