Friday, January 6, 2017
For induction motors if you run the motor at a high flux level the winding flux magnetizing current has a significant third harmonic content that can flow around the Delta winding without appearing in the lines to the VFD.
This is good for the flux waveform but it is not seen by the VFD internal current sensors so you can over-flux and get high motor winding currents giving motor overheating with no indication in the VFD. So with Delta I recommend winding current sensors but this i ...