Please help with VFD selection

[HereinCS]

I was just about to buy the 4kw chinese made spindle motor. For some reason, I thought that it's only equivalent to 3 HP. But talking with Dealers Industrial, I found out that its more like 5hp. That makes the VFD choice much more limited. Am I using too much power? Maybe I'll go to a 2.2kw spindle? Is that enough to cut wood and aluminum? Is an ER16 collet rather than an ER20 a big deal?

In regards to the VFD, I read that I should look for a sensorless speed controller? Did I remember incorrectly? Is this important?

Thanks

[UUU]

I can cut wood and aluminium with a saw, and I don't put out 2.2KW

[wcarrothers1]

down side of the smaller ER is I don't think you can get a 1/2" collet untill ER20 size.. That would sorta suck if you ask me seeing I have alot of .5" bits..

they might have another option but I think the biggest VFD automation direct sells which can operate from single phase is 3hp. I'm sure some one else makes a bigger one that can run from single phase input. get bigger then that and you would have to run a rotary phase converter. I've got one to run my bridgeport although I will admit I would not want to run that all day just to operate my router mill spindle.

b.

[jsheerin]

http://www.google.com/search?hl=en&c...=&oq=&gs_rfai=

4kW = 5.36HP.

Personally I have a 3.7kW spindle and plan to drive it with a Mitsubishi A520 7.5kW drive. This is a 3 phase input power drive, but you can hook it up to single phase if you derate it by a factor of 2.

As far as power, you can cut wood and aluminum with much less power. You just can't cut it as quickly. You can probably search on google and find a machining calculator for aluminum that will give you an idea of how much power you need for a given material removal rate.

I believe what sensorless vector control does in a VFD is give you more torque at low speeds without feedback from an encoder. I've used several VFD's and never really noticed my motor bog down, although I was taking light cuts. So the answer there might be that it could come in handy more if you plan on taking cuts near the limit of your drive / spindle at low speeds, but otherwise it's not strictly necessary.

[underthetire]

I've had very good luck with this company for all my drive stuff
http://www.a-m-c.com/index.html

[HereinCS]

Thanks for the advice guys. I'm glad I discussed it here prior to buying the motor. A household 220v outlet is single phase right? The most that any single phase vfd will put out is 3 hp? That means that, since I'll buy an air cooled spindle, I'll use a 1.5 kw motor. This is only 2 hp. Worse, it only has a er16 collet. Now I'm back to square one. Maybe I'll just buy their package with the VFD.

[jsheerin]

Like I said, you can use some 3 phase input vfd's off of single phase. It's not the cheapest way to go if you're buying new though, but you can get in to higher power drives that way and it's what I'll be doing. From many posts here, I would not buy a Chinese VFD.

[Al_The_Man]

Originally Posted by HereinCS In regards to the VFD, I read that I should look for a sensorless speed controller? Did I remember incorrectly? Is this important? Thanks

Most medium/high end VFD's are Sensorless vector, this refers to the VFD's ability to take a model of the motor and attempt to maintain the optimum vector angle between the rotor and the winding current.
The alternatives are variable speed, which basically outputs the frequency without knowledge of the vector angle.
The opposite end is pulse feedback on the motor rotor to VFD.
Any VFD that has a teach mode for your individual motor is sensorless vector.
Al.

[HereinCS]

Is TECO a good name for VFD?

[awerby]

Originally Posted by HereinCS Is TECO a good name for VFD?

I got one new from Dealer's Electric, and tried to set it up using the (rather cryptic) manual. It didn't seem to be working too well, running hot and sounding funny, so I tried experimenting with various software settings hoping for a healthier response from my spindle. Suddenly there was a flash-bang from the VFD, a bad smell, and no further action from the motor. We sent the VFD back to TECO for evaluation; their tech said it must have been "struck by lightning" and that he couldn't be responsible for "acts of God". I was somewhat dumbstruck at this, wondering if God was working in their factory all this time, or if my experimentation was more inspired than I'd thought. But nothing could persuade them that this was something they were responsible for in any way, despite the unit's still being under "warranty" (read the fine print...)

Fortunately, Harold at Dealer's Electric is a stand-up guy, and he sent me a new Hitachi VFD, which had a much more comprehensible manual (with an index!), set up much easier, and is working to this day. I can heartily recommend Dealer's Electric and Hitachi's VFDs - TECO, not so much...

Andrew Werby
www.computersculpture.com

[wcarrothers1]

My ekstrom is a 2.68hp 8.8A 220v one with a er25 collet.. Working with the 3hp vfd from automationdirect which has single phase input 220.

Seems to work good.. But mroe expencive then any of the china ones.



b.

[HereinCS]

What would happen if I power a 3kw spindle with a 3hp vfd? Does it just not make the power? or is there more to it than that?