[smack]

Sounds like you have potential for a multiple issue situation. I'd make sure the VFD's have the correct Trane TR200 Special Parameter Settings programmed in. If you need them let me know. I can probably email them you. As stated above, the VFD's can be programmed to skip a "critical" speed that is causing vibration issues but I would find it odd that both would have the same critical speed issue especially when you mentioned cavitation. I'd check static as mentioned above. Are there any fire / smoke dampers in the system that could be closed. Also, are the vibrations present through the whole ramp or at the higher end speeds?