# help with VFDs



## jamesrman (Jul 24, 2009)

I need a crash course on VFDs. can anyone recommend a web site that will help?


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## MDShunk (Jan 7, 2007)

The guys who eat, sleep, and breathe VFD's will want to make you think these things are more complicated than they actually are. There, I said it. They're fundamentally pretty simple. They're a motor starter that you can program to run the motor at various speeds. The only course you will need is the damn manual that comes with the VFD brand you select. It's wired pretty much like you would any motor starter. The VFD will have dozens of programming settings to go through, but the manuals guide you right through it. Quite often, you don't need to change a damn thing from the factory preset. The VFD can work right off the "up down arrows" on the frontpanel, or follow a process signal, or have a pot mounted remotely someplace. Just study the manual to YOUR VFD, and you'll be fine. The only questions you might have might be if some terminology crops up in the manual that you're not familiar with.


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## John Valdes (May 17, 2007)

Most all VFD user manuals will have a quick start guide in the very front. This is to get it up and running. Do you have a brand in mind? If so, you can download the manuals in PDF for most every one made.
Like Marc said, they are easy to install and to work with. They all do the same thing. Some are more complicated than others though. 

Check: www.baldor.com
www.tecowestinghouse.com
www.wegelectric.com
www.automationdirect.com

If you deal with a motor shop or power transmission company, they can get you free training.


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## TheRick (Apr 13, 2008)

MDShunk said:


> The guys who eat, sleep, and breathe VFD's will want to make you think these things are more complicated than they actually are. There, I said it. They're fundamentally pretty simple.


HEY! Don't say that too loud, we don't want the boss/customer knowing that stuff do we? :laughing:


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## InControl (Mar 20, 2007)

MDShunk said:


> The guys who eat, sleep, and breathe VFD's will want to make you think these things are more complicated than they actually are.


It depends on the process, Marc. In an open loop circuit, like a fan, than there's a pretty wide window open to where a minor error will be ok. 
Your right, you dont need to be a rocket scientist to figure simple applications out.

BUT....

In some closed loop circuits, where millimeters are critical to a process, like PID loops, than best wishes with your manual.


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## John Valdes (May 17, 2007)

InControl said:


> BUT....
> 
> In some closed loop circuits, where millimeters are critical to a process, like PID loops, than best wishes with your manual.


Thats what the PLC in the system is for. Drives can only do so much. And that is alot, especially with an onboard PLC like ABB has. If you have an application that needs millimeter or nanometer precision, let the PLC do the thinking and let the drive do what it does best, control speed and torque.

Don't get me wrong InControl. The newer drives are extremely smart and keep getting smarter everyday. Precision PID loops can and are manipulated by the drive in many applications.:thumbsup:


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## MDShunk (Jan 7, 2007)

InControl said:


> In some closed loop circuits, where millimeters are critical to a process, like PID loops, than best wishes with your manual.


If millimeters are important, then a servo drive or a stepper might be in a man's best interest.


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## InControl (Mar 20, 2007)

John Valdes said:


> Thats what the PLC in the system is for. Drives can only do so much. And that is alot, especially with an onboard PLC like ABB has. If you have an application that needs millimeter or nanometer precision, let the PLC do the thinking and let the drive do what it does best, control speed and torque.
> 
> Don't get me wrong InControl. The newer drives are extremely smart and keep getting smarter everyday. Precision PID loops can and are manipulated by the drive in many applications.:thumbsup:


It happened sooner than I thought it would. Most major automation manufacturers have the 'all in one' VFD/PLC combo. Great, more software to learn! :wallbash:

Our shop laptop already has @30 different programs that are needed for all of our machines, including DOS programs.






MDShunk said:


> If millimeters are important, then a servo drive or a stepper might be in a man's best interest.


For a smaller motor, absolutely!


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## Chris Kennedy (Nov 19, 2007)

MDShunk said:


> They're fundamentally pretty simple. They're a motor starter that you can program to run the motor at various speeds.


Well put Marc, just cool toys for big boys.


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## MDShunk (Jan 7, 2007)

InControl said:


> I For a smaller motor, absolutely!


I dunno. I've worked on 20hp servo drives, and I can't really imagine anything much bigger having millimeters becoming important. If you're using a VFD, and millimeters are important to you, I'd rather say that you're using the wrong technology.


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## InControl (Mar 20, 2007)

MDShunk said:


> I dunno. I've worked on 20hp servo drives, and I can't really imagine anything much bigger having millimeters becoming important. If you're using a VFD, and millimeters are important to you, I'd rather say that you're using the wrong technology.


What kind of 'work' did you do on these drives?


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## MDShunk (Jan 7, 2007)

InControl said:


> What kind of 'work' did you do on these drives?


Lube and oil change. Rotate tires, etc. :laughing:


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