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Thursday, June 19, 2025 5:28:52 PM

How to Wire 3 hp VFD for 120V Input and Grounding?

2 months ago
#404 Quote
Hi everyone,
I'm working on wiring up a 3 hp VFD that takes 120V single-phase input and outputs 230V three-phase to run a 230V three-phase AC motor. VFD Model: GK3000-SP1S1-2d2
When I received the VFD, it already had some wires connected: a green wire labeled "N" and a red wire labeled "L." I’ve attached some pictures to give a better idea of what’s going on.
I'm very new to electrical wiring, so I'm a bit confused about a few things. Typically green wires are the ground wires, and the green wire in this case goes inside the VFD itself, so I'm not sure where it's attached to. On the external wiring part, there's a screw labeled "E" which in the manual is the ground. Is this green wire the ground wire, just grounded internally? So I wouldn't need to attach a wire to the external "E" screw to ground it?
The VFD also came with 1 red wire, which was attached to the "R" screw. There was then another small red wire that ran from the "R" screw to the "S" screw", then another red wire from "S" to "T". I understand this to be the input power to the VFD, and the U, V, and W screws are the 3-phase 230v output that'' connect to the motor. Most videos I've watched show a red wire and a black wire connected to the R and S screws for 120v 1-phase input. But in the case of the VFD wiring the way it came it's the red wire attached to the R, S, and T screws. I just wanted to make sure that there wasn't another wire necessary, and to clarify which of the R, S, and T screws the wires should be attached to for 1-phase 120v input.
We planned to plug it into a wall outlet using just a typical 2-prong male connector. Is that how we should plug it in as well?
I’d really appreciate any help or advice! Let me know if any more details or photos would help.
Thanks in advance!
0
2 months ago
#407 Quote
Callum wrote:
Hi everyone,
I'm working on wiring up a 3 hp VFD that takes 120V single-phase input and outputs 230V three-phase to run a 230V three-phase AC motor. VFD Model: GK3000-SP1S1-2d2
When I received the VFD, it already had some wires connected: a green wire labeled "N" and a red wire labeled "L." I’ve attached some pictures to give a better idea of what’s going on.
I'm very new to electrical wiring, so I'm a bit confused about a few things. Typically green wires are the ground wires, and the green wire in this case goes inside the VFD itself, so I'm not sure where it's attached to. On the external wiring part, there's a screw labeled "E" which in the manual is the ground. Is this green wire the ground wire, just grounded internally? So I wouldn't need to attach a wire to the external "E" screw to ground it?
The VFD also came with 1 red wire, which was attached to the "R" screw. There was then another small red wire that ran from the "R" screw to the "S" screw", then another red wire from "S" to "T". I understand this to be the input power to the VFD, and the U, V, and W screws are the 3-phase 230v output that'' connect to the motor. Most videos I've watched show a red wire and a black wire connected to the R and S screws for 120v 1-phase input. But in the case of the VFD wiring the way it came it's the red wire attached to the R, S, and T screws. I just wanted to make sure that there wasn't another wire necessary, and to clarify which of the R, S, and T screws the wires should be attached to for 1-phase 120v input.
We planned to plug it into a wall outlet using just a typical 2-prong male connector. Is that how we should plug it in as well?
I’d really appreciate any help or advice! Let me know if any more details or photos would help.
Thanks in advance!

Hi Callum,
1. This 120V 1-phase input and 230V 3-phase output is a customized VFD. The input power supply, 120V is connected to the L and N terminals. You need to short the R, S, and T terminals together. You cannot remove the short wire (red wire) between them. As shown in the attached picture.
2. Your three-phase motor is dual voltage 230/460V; you should connect your three-phase motor according to the low voltage connection method (low voltage mode).
0
ATO.com
2 months ago
#408 Quote
ATO wrote:
Hi Callum,
1. This 120V 1-phase input and 230V 3-phase output is a customized VFD. The input power supply, 120V is connected to the L and N terminals. You need to short the R, S, and T terminals together. You cannot remove the short wire (red wire) between them. As shown in the attached picture.
2. Your three-phase motor is dual voltage 230/460V; you should connect your three-phase motor according to the low voltage connection method (low voltage mode).

So, just to confirm — we should keep the R, S, and T terminals wired the same way as they were originally, correct? Also, to clarify, the green wire that's running internally into the VFD is already grounded, so there's no need to connect anything further to the E (earth) ground terminal, right?
Regarding the green and red wires: am I understanding this correctly — you’ve connected the green wire to the white wire coming from the power supply cable, and the red wire to the black wire? And these two wires are connected to a 2-prong plug that goes into a standard wall outlet?
Lastly, what about the green wire that's currently just resting on the side of the VFD? What is its purpose?
I just want to make sure everything is clear before I proceed with the wiring.
0
2 months ago
#409 Quote
Callum wrote:
So, just to confirm — we should keep the R, S, and T terminals wired the same way as they were originally, correct? Also, to clarify, the green wire that's running internally into the VFD is already grounded, so there's no need to connect anything further to the E (earth) ground terminal, right?
Regarding the green and red wires: am I understanding this correctly — you’ve connected the green wire to the white wire coming from the power supply cable, and the red wire to the black wire? And these two wires are connected to a 2-prong plug that goes into a standard wall outlet?
Lastly, what about the green wire that's currently just resting on the side of the VFD? What is its purpose?
I just want to make sure everything is clear before I proceed with the wiring.

Yes, please keep the R, S, and T terminals wired the way they are. The green wire is N and the red L. You can see the number on the cable. The green and red wires (L, N) are directly connected to your 120V input power supply, and AC power does not need to distinguish between the live and neutral wires. The E on the terminal can be connected to the input power ground wire G.
0
ATO.com
2 months ago
#410 Quote
ATO wrote:
Yes, please keep the R, S, and T terminals wired the way they are. The green wire is N and the red L. You can see the number on the cable. The green and red wires (L, N) are directly connected to your 120V input power supply, and AC power does not need to distinguish between the live and neutral wires. The E on the terminal can be connected to the input power ground wire G.

Great, thanks for clarifying. I think I’ve got it all figured out now. I’ll be using a 3-prong plug with the cord cut, so I can connect the red and green wires, along with the ground wire, to terminal E.
I do have just one final question though. Do I also need to ground the motor to the VFD? I know that I’ll connect the motor wires to the U, V, and W terminals on the VFD, but I’m unsure about the ground connection. There’s a green-painted bolt inside the motor's wiring box, which I assume is for grounding. I’m just not certain if that’s required, since the VFD itself is grounded and serves as the intermediary between the power source and the motor.
0
2 months ago
#412 Quote
Callum wrote:
Great, thanks for clarifying. I think I’ve got it all figured out now. I’ll be using a 3-prong plug with the cord cut, so I can connect the red and green wires, along with the ground wire, to terminal E.
I do have just one final question though. Do I also need to ground the motor to the VFD? I know that I’ll connect the motor wires to the U, V, and W terminals on the VFD, but I’m unsure about the ground connection. There’s a green-painted bolt inside the motor's wiring box, which I assume is for grounding. I’m just not certain if that’s required, since the VFD itself is grounded and serves as the intermediary between the power source and the motor.

Yes, the VFD itself needs to be grounded, and your motor ground wire can also be connected to the ground terminal of the VFD, as shown in the attached picture. This means that the input power ground wire and the motor ground wire can be connected to the same ground terminal, but note that your power ground wire should be separate from the neutral wire N.
0
ATO.com