Greater than four Vac might suggest a capacitor filtering problem or maybe a attainable trouble Along with the diode bridge converter area (forward from the bus). In this kind of instances, consult with Along with the VFD producer in advance of taking even more action. Typical graders have 3 axles, https://motorcontrol23222.bloguetechno.com/helping-the-others-realize-the-advantages-of-motor-pcx-64721674