Another possibility. I don't know if you're using an encoder with the VFD or not, but if you are, you can have a high current problem if the tuning is too tight. The easy way to check this is to change the VFD parameters so that it's using volts / hertz control instead of one of the more advanced control methods. If the output current from the VFD goes down to a normal level, then you know to take a harder look at you parameter settings.