Running 440v 3ph on a VFD?

There is a shop down the road from me shutting down their furniture production facility and the owner has offered to give me a nice 52” wide belt sander for free if I move it. This thing is a beast and I would love to have it in my shop I just don’t know what my options are for running a 440v 3ph machine in my shop. I have 400amp single phase service and a couple of large RPC’s. I believe this thing is 40hp single head so only one motor. I will have to double check on the hp. It may actually be 20HP I can’t recall off hand.

My question to you guys is...would it be possible to have someone like Jack Forsberg to make a VFD capable of running this thing? Would a VFD be capable of bringing the voltage down? I priced a transformer at a little under $3,000. One of my RPC’s is 100hp so it would be capable once I get it installed. I just got this RPC so it’s not up and going yet.

If a VFD isn’t the best route on this for the money I could spend the $3k on a transformer and I am sure that I would have to spend at least another $1k on a switch to turn it on and off. What do you guys think?

I assume your service is 120/240V? If so, then you need a transformer. A VFD will give you 3 phase from single phase, but will not boost the voltage to 480V. If you have a 100 HP RPC, then run a circuit from it to a transformer, then to the sander. If you have a need to run the sander on a VFD, then run 240V to the transformer, then 480V from the transformer to the VFD, then to the sander.

This is something that you need to get a licensed electrician involved in.

I see startup a current problem. Also the utility transformer and feed to your house won’t be adequate. Just because you have a 400amp service box or two 200 amp panels does not mean you can pull that much long term.

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Originally Posted by Bobby Robbinett

... running a 440v 3ph machine in my shop. I have 400amp single phase service and a couple of large RPC’s. I believe this thing is 40hp single head so only one motor. I will have to double check on the hp. It may actually be 20HP I can’t recall off hand. ...

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Check if the motor is dual voltage (240/480). You may be able to run it at 240VAC using your existing RPC (assuming it is 240VAC) just by reconfiguring the sander's motor winding leads..??

Is the VFD intended to provide additional phase conversion capacity? (I'll stay out of your capacity calculations.)

Or do you just want a VFD's soft-start feature? If just for soft-start, you can use any VFD (even the Huanyang-esque units) properly sized for the sander motor's HP and voltage. Since you presumably already have 3-ph to supply the VFD, you don't need to go thru the de-rate math for the VFD input components. I'm not an "RPC guy", so I am making the leap that all 3 legs are suitable to supply a VFD. Someone please smack me if I'm off base on this.

Or is there some specific reason you want/need variable speed? If so, then the VFD is the way to go.

definitely change the machine over to low voltage 3phase power.
check the motor, most are dual rated as in 208,230, 460
controls will be a bigger issue as you will need to change all the coils or get a small boosting transformer for the controls only
b careful with a vfd feeding the control panel as the voltage will go low and burn coils out
pictures would be a big help in figuring this one out
ron

I can't help with the VFD, but I'd be really surprised if the motor is 480v only. Unless it was rewound. It's rare to see controls that are 277v. Most are 120v or 24v. Do some math and figure out how much power you need. 400 amps
may not be enough. Also take a look at the motor starter it may not be rated for x HP at 240 3 phase. Get us all the information and we should be able to find a solution. You should be able to locate a used transformer if you truly need it.

Good luck,
Stan

I have a two headed Scm sandya 7s that requires 164 amps of 230 three phase- not sure you would have enough power with single phase to run the machine

Give up on the idea of using a 20 or 40 HP single phase input VFD.

You already have a phase converter, does it produce balanced output voltages?

If so you could run the 3 phase input VFD from that if you need soft start.

Remember that the other components of the sander cannot be connected to the VFD as they need constant voltage and frequency.....Rod

If you wire that at 240, your current inrush will most likely significantly exceed your available power. Wide belt sanders require a huge amount of inrush when they are starting.

I have a 3 head 52" WBS with two 40 hp and a 30 hp motor, and it takes a lot of power to spin it up.

And have you figured the amount of current inrush to start a 100hp RPC? My 30hp RPC pulls around 125A at startup.

You might want to explore using a 3 phase generator to power it. Unless you are running it a lot the generator may be a better option.

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Originally Posted by Rod Sheridan

Give up on the idea of using a 20 or 40 HP single phase input VFD.

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Why do you say that? I know one reason (highest 1ph in 3 ph out VFD I found was 2HP). Wondering if you have another and/or have source for 1ph in 3ph out VFD more than 2HP?

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Originally Posted by Anthony Whitesell

Why do you say that? I know one reason (highest 1ph in 3 ph out VFD I found was 2HP). Wondering if you have another and/or have source for 1ph in 3ph out VFD more than 2HP?

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I have a couple cheap 1 in 3hp vfd that I got on ebay. 5hp should be no problem. If you use it at a lower than rated capacity you should be able to use a 3ph on single phase as well.

To the OP, That's a heck of a deal!

A quick search on automation direct finds a number of large VFD's that will take single phase in but they are max 230V out. The derating here appears to be 1/4 nominal HP, so the biggest they have will run a 25 HP motor on single phase input at $6k. It seems that your best bet is probably the rotary phase convertor.

Just wanted to update you guys. I am waiting on the electric company to come install a larger line to upgrade my service. Will be going 1,200amp. I have not been able to get back over there and look at the motor plate on the sander but he thinks that it is 440v only and not dual voltage. If that is the case, I can get a transformer from AR for around $3k, or I can take the motor to my electric motor guy and have it rewound for 230v and just buy another magnetic starter/switch. Haven’t looked into the price of a 40hp 3ph 230v magnetic switch as right now I am not sure what the exact amps are. I am guessing this thing is somewhere in the neighborhood of 200amps not counting startup. Will keep you guys posted as this proceeds. Many thanks to all who have commented!

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Originally Posted by Anthony Whitesell

Why do you say that? I know one reason (highest 1ph in 3 ph out VFD I found was 2HP). Wondering if you have another and/or have source for 1ph in 3ph out VFD more than 2HP?

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The rectifier and filter section would be large and expensive for a 30KW single phase rectifier....Rod

Sounds like an amazing opportunity, but perhaps before getting too deep financially into that huge wide belt sander, confirm that it works well and that all the parts are in good useable condition.

It'd really suck to spend a bunch of money upgrading electrical and buying an expensive transformer only to find out down the road the machine has issues.