VFD Setup for controlling multiple machines

nickandersonart

nickandersonart

Joined
Aug 5, 2014
Messages
213
Hey everyone, I'm interested in setting up my VFD that I recently purchased to control more than one machine. I purchased a 2.2kw Huanyang VFD and have currently set it up for my disk grinder and it is working great! Now I'd like to set it up as kind of the main controller for all of my machines. It's rated for the largest motor, so should be able to control the others as well based on what I've read.

I created a diagram below of what I'm intending to do. Essentially, multiple motors controlled by one VFD with external controls mounted at each "station". All motors are 3 phase 220vac, 50hz. I'll only be using one machine at a time. I'm going to be controlling:

1) A 3hp belt grinder
2) A 2hp belt grinder for wood (my older grinder)
3) A 9" Disk grinder
4) My Makita wood bandsaw that I'd like to slow way down for cutting steel as well.

I have three main questions:

First - I'll be switching power to the various motors, as well as the external controls for on/off, reverse, and speed control (potentiometer). What would be the best way to set up a switching box that can accomplish this? What components should I get to set this up? I've read that motors shouldn't be unplugged while being powered by the VFD so the on/off switch should be connected to the control board of the vfd start/stop, not the main power (please correct me if I'm wrong there).
Second, Since the motors have different FLA amperage ratings, as well as slightly different rpm's (between 1400 and 1450 rpm @50hz), what parameters should I set on my VFD so that it can work across the various motors?
Last, do I need to install any kind of overcurrent protection for any of the motors if all running from the same VFD?

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Updated to show most recent switching diagram
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Thank you for the help guys! I'll update the diagram with whatever system seems best for anyone else wanting to set this up.
 
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Last time I was at salems place he showed me his slick setup. He is the guy you want to talk to.
 
Yeap Salem seems to have this all worked out for sure. I'm by far no expert but I think the hardest part of completing like you have is the reversible controllers, speed adjustments and along with the stop start (3phase) at each motor location looks like it would get very expensive.
 
Yeah that looks like way to much work. Salem just has a single controller that's connected to the VFD with accord and it reaches all his machines. He just brings it to the machine he wants to use.
 
Thanks guys I'll have to check out Salem's website. I'm hoping I can use all simple push-button style toggle switches going straight into the com port and simple potentiometers for speed control which shouldn't be too expensive overall unless I'm wrong which is totally possible [emoji15]
 
JT I missed your second post there, ok I could see it working that way, hm good call with the single controller on a cord. I looked all over Salem's website and couldn't find it though, I tried the search too...anybody know exactly where that is?

While the controller on the cord sounds like a good option I'm still interested in the possibility of having controls at each station too, as long as it's not a ton of work. I think the parts themselves wouldn't be too expensive for the whole setup. If anybody has other good ideas on how to accomplish I'd love to know!
 
I use plugs. Each machine has a plug. The pot and fwd/reverse switch are portable, the vfd stays in one place and my disc grinder, belt grinder, and surface grinder run off one vfd. It works, but if I were to do it again, I would take the advice of the others and do what Salem did.

Here's a good thread: http://www.bladeforums.com/forums/showthread.php/1273258-Help-with-switches

And another: http://www.bladeforums.com/forums/showthread.php/977970-3-grinders-1-VFD!!

And another:http://www.bladeforums.com/forums/s...ers-motors-be-hooked-up-to-the-same-VFD/page2
 
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This is the type rotary switch you need for switching the motor. This switch only has 3 positions while you need 4 positions. Good luck finding the 4 position - I looked but didn't find it. https://www.amazon.com/dp/B009IS7SN2/

The controls are all low voltage so might be easier to find. Perhaps a A/B/C/D com switch from computer equip?

On the VFD setting, you'll have to set that for the highest load/current motor and let the smaller motors deal with it. Ideally, you could put a motor overload block at each motor since the 1ph motors will require different than the 3 hp. BUT - I'd expect you could "get by" with only the single protection for the VFD.

Ken H>
 
I use plugs for the 3-phase power to each machine and a control box on a long lead that will reach each of the machines.

I use the factory default settings for the VFD current because my biggest motor is 3 HP and the VFD is rated for 3HP. Even if my biggest motor was only 2 HP, I'd probably still use the default settings.

I have a keyed switch for direction with a key that can only be removed in the forward setting. If the machine in use cannot safely be reversed, the key is removed.

The VFD speed is set to give 0-120 Hz, which gives 0-3600 RPM, less "slip", on a 4-pole motor. As long as all your motors are 4-pole (a bit under 1500 RPM on 50 Hz, a bit under 1800 RPM on 60 Hz), you should be fine. Just be careful you don't connect a 2-pole motor (3000 RPM on 50 Hz, 3600 RPM on 60 Hz) and run it at high speed.

Using dedicated controls at each station and switching the power and control is technically possible, but will take a lot of time, effort and probably money to do. The easiest way I can think of to do it would be to use a multi-step, multi-pole drum switch. I don't know of a manufacturer that produces a switch with enough poles and enough steps though.

I usually use 7 cores to my remote control boxes: 3 for the speed pot, common, forward start, reverse start and stop. To keep things simple, you'd want a 4-step, 10-pole switch, giving a set of poles for each of the 7 control wires plus another for each of the 3 phases, though you could probably keep one end of each of the pots permanently connected and keep the commons permanently connected, reducing the switch to a "mere" 4-step, 8-pole.

For more than 2 motors, the plugs and moveable control box looks a lot easier to me.
 
If you go with a rotary switch, but cant find a switch with enough positions for all your machines.
You can make do with two or more switches of the common 3 position type.
For example, one switch can send power direct to your two most often used machines. Its third position, sends to another rotary switch what could send power to 3 other machines. Or whatever combination you wish to configure.

But, For a small one man shop, I think thats alot of fiddle work.
Just fit plugs to each machine will be much easier.
Or just connect each machine to a common power bus.
Obviously you are not stupid enough to switch on more than one machine at a time...

Put the VFD controls on a long enough cord to reach each machine.
 
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Ok sounds good guys thanks for all of the suggestions. I think I will start with the plugs/controller on a cord style and then maybe upgrade to rotary switch in the future for the motors.

And Timgunn, I would love to see what a grinder with 3000rpm motor would look like running at double frequency. The old Fugs song "I want to know" comes to mind... [emoji1]


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I run 6 grinders on one VDF I tried the plug set up and found it a pain in the butt. Since I when with a switch to each grinder life is good . Run a wire from you motor to your switch . Then from each switch to a junction box join all your wires then one up to your VDF.
I have one switch for each grinder. You can only run one grinder at a time.
I tried posting pictures but have no idea how to do it here.The link might work
 
Kevin Cox said:
RqDExAl.jpg

I run 6 grinders on one VDF I tried the plug set up and found it a pain in the butt. Since I when with a switch to each grinder life is good . Run a wire from you motor to your switch . Then from each switch to a junction box join all your wires then one up to your VDF.
I have one switch for each grinder. You can only run one grinder at a time.
I tried posting pictures but have no idea how to do it here.The link might work
Click to expand...
I like the hollow grinding jig how does it work for you?

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Hey guys, one more question...why does the potentiometer have two leads connected to the third pole as shown in the diagram? And what does the oval symbol stand for just above the text "input current"?

I also saw that the count, in another post, had a similar diagram showing two leads coming off of the third pole of the potentiometer with a symbol "FM". What does that refer to exactly...frequency modulation?

The above diagram is mine, manual is from a Chinese manufacturer but still kind of understandable, and seems similar to the one posted by the count (below) so I'm guessing it's a similar setup.

Thanks guys ;)

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I think the "AI" input terminal is for a current input. A 0-20 mA or 4-20 mA current signal is commonly used in industrial control systems.

"We" tend to use a Voltage signal provided by a potentiometer which is connected to VI.
 
Tim Gunn always has really good detailed answers to VFD questions, but I'll toss in the simple answer to the pot. The two ends of the pot connect to the terminals, one is ground, other terminal provides DC voltage, with the 3rd (middle) wire providing the variable voltage signal to VFD to determine output speed depending on amount of resistance dialed in with pot.
 
Thanks for the quick responses guys. The main point of confusion for me is why there are two leads off of the lower end of the potentiometer going to two sources. The above diagram (mine) shows it being split between the acm/ground and the "ai" pin with that oval symbol in between. Is that a symbol for an actual component that I should place in there or can I just connect the cables together there? I noticed that the count had a similar element shown where the two leads split listed as "fm". Any ideas on what I should do there?


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