VFD grounding question

[Lee Alkureishi]

Hi all,

I finally got my VFD in the mail today

I got started with wiring it up, and got stuck when it comes to grounding...

The VFD is a Huanyang 1.5kW (2hp), which accepts 110v single phase in and outputs 3 phase. I wired up a plug on some 12 gauge grounded wire. The black is going to R, white to S, and green to E. I powered on the VFD, and it works fine.

Next, I'd like to connect my motor. It's a Leeson 2hp 3 phase motor. Inside the wiring box, there are 4 sets of wires. 4 pairs, which I believe are the 3 input lines for the 3 phase power. I think it's ok to connect these in any order to U,V and W on the VFD.

The 4th set of wires is (I think) for ground. It's 3 wires twisted together, and it has a wire connector cap on it. There is a green screw on the motor body itself, but the wires are not connected to it.

So, how do I properly ground this motor/VFD combo? As I understand it, it's ok to connect the three ground wires to each other but not to anything else. But, how does the correct grounding transfer back to the VFD? Or does it not need to, as the VFD is grounded via the power cable? Does anyone have any experience of this with the huanyang (or similar) VFDs?

Thanks in advance for any advice you can offer!

Lee

[Steve Harder]

I AM NOT a licensed electrician - but I will make a comment.

Many 3 phase motors can be used on several different voltages.

Each of the yellow wires coming out of the motor may have a "letter or number" label on it - which may be referred to on the motor label or documentation.

My "unlicensed guess" is the red capped wires are not connected to anything - they are just connected to each other. The motor would be grounded by connecting your green wire to the motor frame. And the three phase would go to the three bare end pairs. If this is a 'used' motor, you want to find some docs for it that allow you to make sure the motor is 'configured' for your voltage. Changing voltage would involve swapping labelled wires between the bare end pairs and the group in the red cap.

Here's a diagram to give you idea of what's going on -- this IS NOT for your motor.Motorwiring.jpg The "INS" means tied to each other and insulated with the red cap.

[Lee Alkureishi]

I AM NOT a licensed electrician - but I will make a comment.

Many 3 phase motors can be used on several different voltages.

Each of the yellow wires coming out of the motor may have a "letter or number" label on it - which may be referred to on the motor label or documentation.

My "unlicensed guess" is the red capped wires are not connected to anything - they are just connected to each other. The motor would be grounded by connecting your green wire to the motor frame. And the three phase would go to the three bare end pairs. If this is a 'used' motor, you want to find some docs for it that allow you to make sure the motor is 'configured' for your voltage. Changing voltage would involve swapping labelled wires between the bare end pairs and the group in the red cap.

Here's a diagram to give you idea of what's going on -- this IS NOT for your motor.Motorwiring.jpg The "INS" means tied to each other and insulated with the red cap.

Hi Steve,

Thanks for the info, they do indeed have letter/number pairs on them. I'll look up my motor's information on which voltage it's set up for, and pair it to my VFD's output voltage.

You mentioned that the green wire should go to the motor's frame - which green wire? The power cable green wire is hooked up to earth on the VFD, which will then pass 3 wires from U,V and W terminals to the three bare end wire pairs. As it stands, I don't have a separate ground wire running from the VFd to the motor - should I have one? Which terminal should it come from on the VFD side?

Thanks again,

Lee

[Steve Harder]

Once again - "not a licensed elec ..." - you should have 4 wires between VFD and motor - one of them ground. You can pick up the ground at the vfd where you connected the ground from your singlephase input -- or most VFDs will have another terminal near where you take off the 3phase to the motor. Basically the ground gets connected to the metal chassis of the VFD and then on to the metal framework of the motor. (Twisting the wires together in a spiral can help cut down electrical nosie from the VFD - you will notice that elec noise if you use an AM radio in your shop.)

Note the green wire in the upper left diagram, coming off a ground terminal near the 3phase output terminals. (The B1,B2 terminals are for an optional ballast resistor, don't get confused by them. Normally no connection to B1,B2.)


Here's a link to an automationdirect VFD installation: http://www.automationdirect.com/static/manuals/gs2m/ch2.pdf

[Lee Alkureishi]

Great, thanks! That's the info I needed

I might have run into another snag, though... I noticed that the VFD (the manual is mostly in chinese) has this written on the side: "output: 3ph 0-110ac 1.5kW 13a". Does this mean that it's not suitable for use with a 220v motor?

I didn't even know it was possible to find anything in 110v 3-phase - does that even exist? My understanding when I bought this VFD was that it would power a 220v 3 phase motor.

Or, am I reading this wrong?


Thanks again!

Lee

[Steve Harder]

I can't offer any advice on your VFD.

But I will suggest you email the tech support folks at automationdirect.com. When I was converting to VFD they were extremely helpful and very knowledgeable. Even though you don't own their equipment, I'm betting they may be able to shed some light on your equipment.

Googling your equipment name I did find this posting: "Look at CNC zone, and search for "Huanyang Chinese VFD settings and manual here" in the DIY-CNC router machines forum for a link to the manual (and recommended settings) and very relevant discussion."

I can say that I've been very happy with my automationdirect 2hp vfd.

[Lee Alkureishi]

Very interesting update: I emailed the Chinese importer company I bought it from, and they've been very responsive and very helpful. They've stated that they're very sorry for the misunderstanding, as they thought that the motors in the USA were all 110v. However, they said that the model of VFD I received will also accept 220v input, and will output 220v 3-phase - happy news!

Incredibly, they also suggested that I buy a step-up transformer to achieve the 220v input, and have said that they will reimburse me when I show the receipt! Not sure I'll take them up on that, but I'll probably just run a 220v line out to my garage instead.

Thanks again for all your help and advice,

Lee