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Have the TECO 7300CV - 220v single phase in, 220v three phase out. The manual clearly shows the motor ground connection going to the "PE" terminal but it does not show the source / panel ground connection. There is another "PE" terminal but I'm hesitant to hook to this on account of all the horror stories I'm reading about misconnections and smoking units. I'm also weary because I know there's a 120v potential between my panel ground and each 220v leg, whereas there is no potential between ground and one of the legs on the 120v input VFD's - but does this matter? Should I connect to the other "PE" terminal? Also, there is no chassis ground screw on the VFD, or anything labeled "ground" for that matter.

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Both the motor frame and the chassis or mounting bracket of the VFD should be connected to the ground terminal in the power distribution panel. The neutral of the 120/240 system should be connected to ground only at the service panel. The ground point at the service panel should be connected to a nearby ground rod driven into the ground. What is the PE terminal in the VFD connected to if not the chassis or mounting bracket? It shouldn't be connected anywhere else. Is the manual that you are looking at available online?

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  • \$\begingroup\$ The case of the VFD is entirely plastic. No metal whatsoever. tecowestinghouse.com/Manuals/… \$\endgroup\$ – John Meiers Nov 9 '16 at 4:31
  • \$\begingroup\$ I don't see either a ground or a PE terminal in the diagrams that show the other terminals. I looked at the section on page 3-10 where is says to ground the ground terminal of the inverter, but I see no terminal marked PE or ground. Where is the PE terminal mentioned in the question? What are is it connected to? Is the unit mounted using holes or slots in the plastic? Is the heat sink entirely enclosed in plastic with no exposure to the outside? \$\endgroup\$ – Charles Cowie Nov 9 '16 at 16:06

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