One way to avoid the arcing problem is to add some inductance to each phase between the VFD and motor. The inductors slow down those fast switching edges and protect the motor windings. If you know what you are doing you can also add some capacitance after the inductors to get an almost perfect sine wave. You have to be careful doing this if you vary the speed because you can get resonance between the inductors and capacitors which will do odd things to the voltage at some frequencies.
A while back I scored a large 240->415 (UK mains voltages) auto transformer so I now have a 415 single phase main that I use to supply VFDs on my converted 3-phase machines. Les > This sounds to me like a likely culprit. The high-frequency, high-amperage > switching on the output side of a VFD causes high voltage transients which, > if the motor isn't rated for VFD duty, can pierce the winding insulation > and cause internal arcing and carbon tracks. You may be seeing higher > current simply because the windings are now shorting together in a few > spots. ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
