quick question about 3 phase motors with VFD

[mreza Salav]

I'm about to purchase a used bandsaw with 3 phase motor. I have attached a photo of the name plate of
the motor. It is 3HP and stated 440/220 V which I suppose it means it can be run on either 440 or 220 three phase:
234937
Since it is only 3HP I am thinking of getting a VFD to run it of 1 phase power like the following ones:

http://www.factorymation.com/s.nl/it.A/id.198/.f?sc=2&category=32
http://www.ebay.com/itm/330691840872?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Can you please confirm that this will work fine or am I wrong on something?

thanks

[David Kumm]

Mreza, call factorymation and verify. You want to be sure the output amps are 10 with a single phase input- so the vfd needs to be rated at about 20 amps in. Make sure the unit allows for constant torque programming and ask the guy about wiring it. The bandsaw starter will need to be removed or bypassed and if there is a kill switch on the foot brake or on the wheel if the blade snaps you will have to wire those to the vfd. I have not bought from Factorymation but the OWWM guys swear by them. Dave

[Trevor Howard]

To add to Davids great info. Looking at the Factorymachine specs, it does not show the Input Current for the selected voltage, single or 3 phase. Which as David said, you need to make sure your getting 10Amps output on single phase. As an example here is another drive, a little more expensive. the GS2-23P0 from Automation Direct. If you look at the specs here

http://www.automationdirect.com/static/specs/gs2drive.pdf

On page 3 it shows you that with 240 single phase you need 27Amp input circuit, but only 12.5Amp circuit on 3 phase.
I have used both Factorymation and Automation Drives and they are great drives for the price. And they both have many features that are programmable for different situations.
Good Luck

[mreza Salav]

Thanks for the comments. I called Factorymation and talked to a tech support member. She confirmed I can get 10amp on the output using single phase source,
and as David said, I'll wire the bandsaw directly to the VFD (bypassing the switch).
There are some extra multifunction input which apparently can be used for emergency stop switches, and she said the micro-switch (if there is any) can be wired to those.

I'm completely new to this 3 phase thing and honestly I don't know why if the output of VFD is a 3phase power source motor and micro-switch should be directly wired to the VFD and by-pass the switch on the bandsaw. Some learning is in order I guess.

[Michael W. Clark]

Good subject, I would like to learn more about this as well. I have a 5HP 3ph TS with a static converter, which I would like to change. Do you plan to install this at the machine or create 3ph circuit for multiple machines?

Mike

[David Kumm]

You never want a magnetic switch between the motor and the vfd. I have left manual starters in place and in the on position if I don't want to screw up the option to run on my RPC but you don't want to use it to switch off the machine except in an emergency. Disconnecting power from the output side causes some degradation of the circuits internally after some period of time. That is as technical as I get. You will want a switch or disconnect on the input side as vfds have no way to turn on or off on their own. A regular 220 switch rated at 30 amps will get you there. You can switch a vfd between machines but a PITA and once programmed for a certain machine it is best to leave it committed there. If you don't need speed control and have several machines an RPC or better yet a Phase Perfect is the way to go. All of the above are preferable to a static converter. Dave

[Van Huskey]

Note there is a low voltage circuit provided by the VFD which can be wired through the micro-switches to cut the power to the motor off. This is different from running the full voltage 3ph power through the main mag switch. As Dave said you do not want ANY potential cut off between the 3 phase output of the VFD and the motor, it is apparently bad for the VFD since if you cut the power in between them the VFD does bad things to itself trying to identify the load that is no longer there. That is also as technical as I get...

You can wire a "standard" on off switch to the low voltage accessory circuit of the VFD so you can have a switch in the standard position if you like, my understanding is this does NOT work with a magnetic switch, I ASSUME because the voltage/current through this low voltage low current circuit is not enough to keep the contactors closed and the mag switch "thinks" power has been cut and thus will not stay closed.

[mreza Salav]

Thanks for the advice.
I am considering buying a bandsaw that has a 3 phase motor; so I'm debating whether I should swap the motor to single phase (probably the swtich too?) or get a VFD to get it running. Depending on what I can find for a replacement motor (and at what cost) the hassle of swapping the motor (perhaps to a bigger one) might be less.
All of these are adding to the complication as the saw is a Griggio SNA600 (yes, it's the same model but a different seller) that is 900km away and I'm trying to get it shipped here.

[Van Huskey]

If it were me AND the motor was 3hp or less allowing for use of inexpensive VFDs I would keep the 3ph motor. 3ph motors are simple, no caps to go bad and soft start, motor braking and even variable speed are useful on a woodcutting bandsaw, again if it is 3hp or smaller when talking new for new the VFD solution will almost certainly be cheaper too.

[mreza Salav]

It's 3hp Van.
I'm in the middle of trying to arrange for shipping it and hopefully find someone (other than the seller) take a look at it before he crates it to be shipped.

[Chris Parks]

Most people would look down on the Chinese VFD's as in the OP's second link as cheap junk. I have used at least ten of the 4KW Huanyang which is the brand in the Ebay link and none have failed and they are driving 5hp cyclones every day. We went to a different type of Chinese VFD and they also have given good service with no issues. The only reason for the change was the newer type has a rotary speed controller which we can utilise. The big VFD advantage is a soft ramp up with no big power draw and they can be programmed as we do to ramp down slowly which scrubs the air in the shop after the machining finishes.

[Michael W. Clark]

Thanks Van and David, that answered my question. Sorry Mreza if I took away from your post. I could imagine a lot of benefit to a VFD on a bandsaw and I think you will spend nearly as much money (probably more) for a new 3hp single phase motor.

[Van Huskey]

Most people would look down on the Chinese VFD's as in the OP's second link as cheap junk. I have used at least ten of the 4KW Huanyang which is the brand in the Ebay link and none have failed and they are driving 5hp cyclones every day. We went to a different type of Chinese VFD and they also have given good service with no issues. The only reason for the change was the newer type has a rotary speed controller which we can utilise. The big VFD advantage is a soft ramp up with no big power draw and they can be programmed as we do to ramp down slowly which scrubs the air in the shop after the machining finishes.

I have often wondered about those, I may try one now. Thanks for the input!

[mreza Salav]

Thanks Chris. If they work in my situation I would consider those (and perhaps get a larger one that can supply larger than 3HP).

[Ryan Brucks]

what a coincidence. I just this morning finished installing a 5hp 3 phase leeson motor to a Yaskawa V1000 VFD. The VFD takes 1 phase and turns it into 3 phase. You have to double the power rating when doing this. So if your motor FLA was 10, you want a three phase VFD capable of at least 20amps (like David said already).

Jerry Work wrote a guide on doing this with a 5hp felder
http://thedovetailjoint.squarespace.com/storage/Felder%20RL-200%20install%20using%20VFD.pdf

I also purchased the VFD from Power and Control, mentioned in that link. Glenn and Kyle Woodbury are very knowledgeable about these drives and will be able to figure out something and tell you how to wire it any way you want. They know their products really well I have found.

[mreza Salav]

Ryan, I got confused with the numbers a bit. Are you saying that if the FLA of the motor (in 3 phase) is 10 you need a VFD that is capable of providing 20amps on the output?
Or are you saying that it should be able to have 20 amps on single phase (on its input)?
I checked with the tech support of factorymation (the first link) and they confirmed that the particular model linked (which provides 10.5amp on output) is good for running a
3phase motor that needs 9amp (a 3HP motor).

[Ryan Brucks]

I find that odd, given the stats on page 3.

Look where it says power ratings (A) and there are two numbers for each. Ie, the first one says 6.3/2.9. The field above shows single/threephase. This leads me to believe these VFDs are just like the other ones I have researched, but to be honest I am no expert and they could be different.

Normally you need the model to be able to handle double the power when converting single to 3 phase. It makes sense when you think about it. A single phase 5 horse motor has an FLA of 20-22. A three phase 5 horse motor has an FLA of 12-13. Obviously some of this extra power has to be eaten by the VFD to convert to the three phase. Can't magically convert 12amps three phase from 12 amps single phase when you think about it without lots of losses.

I would question what you were told and keep researching until you are confident.

[Ryan Brucks]

Clarification: I see you never mentioned single/3 phase in the tech support reply. The double power requirement is only when converting phase.

So what they said is technically correct if you forgot to ask about phase conversion too. Or did they actually say that was true for single phase input and 3 phase output?

[Ryan Brucks]

This chart shows converting amps from single to 3phase:

http://www.engineeringtoolbox.com/ampere-phase-d_449.html

Looking at the 240v single/3phase part of the graph, it's pretty darn close to the 20/12 FLA figures between 5hp single and 3 phase motors. So I am now pretty confident in saying that yes you always need roughly double power when converting phase.

[Ryan Brucks]

their 3hp model GS2-23PO says its rated for 27/12.5a.

That means when converting from single to three phase it can handle 27a input. More than enough since your 9a motor will only need 18 or 20 amps input from the single phase as an estimate on the high side.

[Ryan Brucks]

oops, I got my wires crossed. I mentioned the automationdirect one instead of your first link (name too similar lol).

That first TECO one you mentioned I do not think will work. I think you need the TECO listed as 20a.

[Ryan Brucks]

for the TECO you would want this model:

http://www.tecowestinghouse.com/teco/products2.aspx?partID=MA7200-2005-N1&partIDExt=blk&command=detail

to buy:
http://www.factorymation.com/s.nl/it.A/id.220/.f

MA7200-2005-N1

[Van Huskey]

Either I am completely stupid <very possible or won't this one work for a lot less money:

http://www.factorymation.com/s.nl/it.A/id.198/.f?sc=2&category=32

[Ryan Brucks]

It will only power a 5fla, 3 phase motor when converting from single phase. It will not work.

You need to double the power rating when converting phases. Otherwise we would be getting free energy.

[Ryan Brucks]

This explains derating supplies when converting phase. The factor is actually 1.73, but 2x is used for simplicity and to give room for error I guess.

http://www.precision-elec.com/derating-three-phase-vfd-for-single-phase-power-2/

[mreza Salav]

Either I am completely stupid <very possible or won't this one work for a lot less money:

http://www.factorymation.com/s.nl/it.A/id.198/.f?sc=2&category=32

Van, that's what I linked in the original post.

Ryan, either I'm not understanding you or you are confusing something (or both ;)).
The one I (and then Van) linked specifically says it is rated for 3HP output, see the specification here:
factorymation.info/acdrives/FM50Specs.pdf

It is rated for 10.5amp on output (3phase, 230v). The motor I have listed needs 9amp on 230V (or 220?) 3 phase.
What David was suggesting (I think) is to check that the draw on input of the VFD when supplied with single phase can provide that much output. In this
case for example, the VFD on single phase input draws close to 20amp. If this is what you mean we are in agreement.
I did talk to the tech support group at factorymation about this specific unit and specifically about a motor I want to use on (with FLA of 9 as shown in my photo)
and they confirmed that this works fine.

[Ryan Brucks]

Yes. I know it says its rated for 3hp three phase and 10.5a.

But when you are feeding it with single phase, it requires almost twice the power to generate that same amount of power in 3 phase. So you always need to "de-rate" the VFD in this application. That means you take the published specs, and cut them down by that 1.73 factor.

So those specs when used in the single to 3 phase conversion application are indeed HALF what they are advertising.

Other vendors make this clear. They are just not listing it.

[Ryan Brucks]

Van, that's what I linked in the original post.

I did talk to the tech support group at factorymation about this specific unit and specifically about a motor I want to use on (with FLA of 9 as shown in my photo)
and they confirmed that this works fine.


Unless you told them you are converting from single phase, you didn't tell them everything they needed to answer properly.

[Alan Schaffter]

It will only power a 5fla, 3 phase motor when converting from single phase. It will not work.

You need to double the power rating when converting phases. Otherwise we would be getting free energy.

Please explain. Am I missing something? The FM50 203C manual and spec sheet state; 3 ph, 230V 10.2A output with "1/3 phase, 230V input". Is there a footnote I missed that says the output current rating must be derated for single phase input?

I can understand derating the output current if the rating given was for 3 phase input only, but that is not how I would interpret the literature.

[mreza Salav]

Unless you told them you are converting from single phase, you didn't tell them everything they needed to answer properly.

Yes I did and it was confirmed.

[Ryan Brucks]

ok, sorry. never mind me. I simply thought you might have missed that part about the phase conversion. If they are saying that's what it can handle, I will believe them.

[Ryan Brucks]

Just to be on the safe side I am going to talk to the VFD guys from power and control and get their take on that data sheet. I will post back when I hear from them.

[mreza Salav]

Yes. I know it says its rated for 3hp three phase and 10.5a.

But when you are feeding it with single phase, it requires almost twice the power to generate that same amount of power in 3 phase. So you always need to "de-rate" the VFD in this application. That means you take the published specs, and cut them down by that 1.73 factor.

So those specs when used in the single to 3 phase conversion application are indeed HALF what they are advertising.

Other vendors make this clear. They are just not listing it.

Just a small correction: I doubt (with my limited knowledge) that you need "twice the power", as the amount of loss in VFD isn't that much, but if you meant twice the amp
(in the single phase input vs. the 3 phase output) then I agree (and I said it earlier).

[David Kumm]

It's always best to see the electrical spec badge right on the vfd and verify both input and output amps and voltage range. Vfd's are also a great way to deal with some of the old 200 volt motors out there. The badge should also give the variable and constant torque amp output. Dave

[Ryan Brucks]

oops you are indeed right. I shouldn't have said power. too hasty. obviously the chart shows power (VA) staying the same. And the losses from the VFD are probably small but I am guessing that's why sometimes a factor of 2 is used instead of exactly 1.73 for derating... maybe to account for inefficiencies?

[Ryan Brucks]

Real quick thing to point out David: These FM50's I don't think can do different voltages on the output. I think you do need the 7200 series for that or another brand.

[Van Huskey]

I think I can put this to bed, I called my "cuz" (no relation) who is the god of all things motor control, I hate to call him since he is working out of the country but it was killing me, he says:

You have to double a VFD rating IF and only if BOTH of these are true:

1. The VFD in question is NOT rated for single phase input
2. The specs say it WILL work with single phase input

The second half seems strange but there are some VFDs that are designed to run on 3 phase but will accept single phase but need to be derated. The drive in question which he knows well is rated for single phase input and thus does NOT have to be derated.

The FM50 Prushan and I linked to WILL work for a 3ph 3hp motor with 1ph input fine as long as the 3ph motors FLA is no higher than 10.5 FLA. Which jives with my experience of several people running 3hp 3ph motors with that exact drive.

[David Kumm]

Real quick thing to point out David: These FM50's I don't think can do different voltages on the output. I think you do need the 7200 series for that or another brand.

Correct, the FM50 is more basic.

Van, most vfds will operate with single phase in even if not stated. The Hitachi j300 needs to be jumped between two leads on the input side, most others just accept input on two of the three. Prices have come down so I've found that anything under about 20 amps input is reasonable new, over 25-30 amps in can be had used for 350-450 but you have to watch as more people are finding out that they will serve larger motors. The largest I have is 54 amps input and paid about $400. Dave

[Van Huskey]

Van, most vfds will operate with single phase in even if not stated. Dave

He didn't say anything about that senario and I am sure you are correct. He was clear the single phase rated Teco FM50 does not have to be derated, it will handle its rated FLA with either single or three phase input on the smaller drives rated for single phase input. My guess is the larger FM50 drives would indeed have to be derated for single phase input.

[Kevin W Johnson]

for the TECO you would want this model:

http://www.tecowestinghouse.com/teco/products2.aspx?partID=MA7200-2005-N1&partIDExt=blk&command=detail

to buy:
http://www.factorymation.com/s.nl/it.A/id.220/.f

MA7200-2005-N1

This requires 3 phase input for anything above 3hp, if he already had 3 phase he wouldn't need this. And while it can run up to 3hp on single phase, so will the TECO FM50-203c, at a much lower cost.

[Kevin W Johnson]

I'm about to purchase a used bandsaw with 3 phase motor. I have attached a photo of the name plate of
the motor. It is 3HP and stated 440/220 V which I suppose it means it can be run on either 440 or 220 three phase:
234937
Since it is only 3HP I am thinking of getting a VFD to run it of 1 phase power like the following ones:

http://www.factorymation.com/s.nl/it.A/id.198/.f?sc=2&category=32
http://www.ebay.com/itm/330691840872?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Can you please confirm that this will work fine or am I wrong on something?

thanks

I have the TECO FM50 203c on a PM66 table saw with a 2hp 3ph Baldor motor, and I'm completely happy with it. In fact, I'll be buying another one soon to power a 1.5hp 3ph Leeson that I bought in Richmond the other day for $3, yep, $3.

[Rod Sheridan]

There's a lot of confusion on this subject.

The issue with converting single phase to 3 phase with a VFD is as follows

- the VFD is a rectifier and inverter in one package. The rectifier converts the incoming AC into DC, the inverter converts the DC back into 3 phase AC and can vary the voltage and frequency.

- when you rectify single phase AC, you convert the sine wave to to a two pulse waveform. The rectifier has to filter, or smooth out this waveform to convert it from two mountains, to a straight line (waveshape).

- the filter capacitors and rectifier diodes can only handle so much current, they have to provide large pulses of current from the two mountains to fill in the valleys to make a straight line waveform (DC).

- if you feed 3 phase power into a VFD, instead of two mountains, you get 6, with each one shifted 60 degrees along so it now looks more like a saw blade with small mountains and most of the valley filled in. This means smaller filter capacitors and diodes, and lower input currents.

Sorry about using wood working images in an electrical discussion however it may help illustrate the problem.

So after a certain size of VFD, they would be derated if run on single phase power due to diode/filter issues. This seems to most prevalent around 3 HP output or larger, which require derating when single phase input is used.

Regards, Rod.

[Michael W. Clark]

Note there is a low voltage circuit provided by the VFD which can be wired through the micro-switches to cut the power to the motor off. This is different from running the full voltage 3ph power through the main mag switch. As Dave said you do not want ANY potential cut off between the 3 phase output of the VFD and the motor, it is apparently bad for the VFD since if you cut the power in between them the VFD does bad things to itself trying to identify the load that is no longer there. That is also as technical as I get...

You can wire a "standard" on off switch to the low voltage accessory circuit of the VFD so you can have a switch in the standard position if you like, my understanding is this does NOT work with a magnetic switch, I ASSUME because the voltage/current through this low voltage low current circuit is not enough to keep the contactors closed and the mag switch "thinks" power has been cut and thus will not stay closed.

I apologize in advance for my electrical ignorance, what would be the preferred way to switch the power off to the equipment? If I understand correctly, one of the benefits of the mag switch is that the motor won't re-start from a power dip without pushing the start button. I would like to retain this feature, maybe the VFD already does this?

Also, I have a knee kick that I use to turn the motor off on my table saw so I don't have to remove my hands from the workpiece if I think things may go awry with the cut. This is largerly a physical/geomertry kind of thing, but I don't see it working well with small push buttons on VFD's. I think you would want some type of stop push button to allow you to actuate it with a lever.

Last question, are there any code requirements pertaining to the disconnect before the VFD? I was told I had to put a disconnect before my phase converter. I actually like the disconnect for blade changes, its a good positive way of interrupting the juice and I imagine that I could re-use it if requried.

[Kevin W Johnson]

I apologize in advance for my electrical ignorance, what would be the preferred way to switch the power off to the equipment? If I understand correctly, one of the benefits of the mag switch is that the motor won't re-start from a power dip without pushing the start button. I would like to retain this feature, maybe the VFD already does this?

Also, I have a knee kick that I use to turn the motor off on my table saw so I don't have to remove my hands from the workpiece if I think things may go awry with the cut. This is largerly a physical/geomertry kind of thing, but I don't see it working well with small push buttons on VFD's. I think you would want some type of stop push button to allow you to actuate it with a lever.

Last question, are there any code requirements pertaining to the disconnect before the VFD? I was told I had to put a disconnect before my phase converter. I actually like the disconnect for blade changes, its a good positive way of interrupting the juice and I imagine that I could re-use it if requried.

As stated earlier I have a Teco FM50 203c. I have mine wired using the original mag starter and on/off buttons. What was said above is that you can't use the mag starter to cut power, however it can be used to control the VFD. Below are a couple of wiring diagrams. One without e-stop, and one with, however it (e-stop version) doesn't use the mag starter. I can send you a link to a discussion on this topic over at the OWWM forum if you like, I can't post it in the open as it violates TOS here.

[Van Huskey]

I think Kevin cleared it up but I do have a question but I will get to that in a moment.

Most VFDs have a low voltage (in the case of the FM50 it is 12v, many use 24v) auxillary circuit that can be used to "tell" the VFD to cut power to the load (motor). You could think of this like a low voltage switch that runs a relay to turn high voltage power on and off to a machine, like the Long Ranger setup that turns on a dust collector when a blast gate is opened. It can also handle reversing on machines like lathes. The diagrams Kevin put up show this, besides a main on and off button you can also wire in emergency stop buttons or switches like a large slap switch or for example micro-switches in the doors or connected to the foot brake of bandsaws.

Here is my question since Kevin or someone else may be able to correct me. My understanding is the low voltage (low current) auxillary circuit we are discussing would NOT work with the machines standard mag switch. My understanding of this is because the voltage and or current is not high enogh to keep the mag switches contactor closed, in this case the magnetic switch would "see" the 12V as a cut power situation and open and remain open. Can comeone confirm whether the use of a mag switch in this manner will or will not work?

[Kevin W Johnson]

I think Kevin cleared it up but I do have a question but I will get to that in a moment.

Most VFDs have a low voltage (in the case of the FM50 it is 12v, many use 24v) auxillary circuit that can be used to "tell" the VFD to cut power to the load (motor). You could think of this like a low voltage switch that runs a relay to turn high voltage power on and off to a machine, like the Long Ranger setup that turns on a dust collector when a blast gate is opened. It can also handle reversing on machines like lathes. The diagrams Kevin put up show this, besides a main on and off button you can also wire in emergency stop buttons or switches like a large slap switch or for example micro-switches in the doors or connected to the foot brake of bandsaws.

Here is my question since Kevin or someone else may be able to correct me. My understanding is the low voltage (low current) auxillary circuit we are discussing would NOT work with the machines standard mag switch. My understanding of this is because the voltage and or current is not high enogh to keep the mag switches contactor closed, in this case the magnetic switch would "see" the 12V as a cut power situation and open and remain open. Can comeone confirm whether the use of a mag switch in this manner will or will not work?

In the diagram I posted, the magnetic contactor (coil) is being operated by the incoming 230v, we're simply using the contacts to make or break the 12v signal that tells the VFD to turn the motor on and off.

[Van Huskey]

In the diagram I posted, the magnetic contactor (coil) is being operated by the incoming 230v, we're simply using the contacts to make or break the 12v signal that tells the VFD to turn the motor on and off.


AHHHH, I see says the blind man!

[Michael W. Clark]

Thanks, I see there is a lot of capabilities with the VFD's. It seems like if I put the mag switch before the VFD (line side), then I get the benefits of the mag switch and loose the SPC.

This completely has nothing to do with the TS application, but If you were using the VFD to control motor speed, then I suppose your control signal would go into this low voltage signal input? Its not just on/off, its variable 0-12V, 4-20mA, 0-24, etc? I've designed some industrial DC systems with VFDs, but I'm mechanical and haven't gotten into the details of which wire goes where. I may not "need" to know it, but I sure like having an understanding so I'm not completely lost when the electricals are talking.

Mike

[Van Huskey]

Thanks, I see there is a lot of capabilities with the VFD's. It seems like if I put the mag switch before the VFD (line side), then I get the benefits of the mag switch and loose the SPC.

This completely has nothing to do with the TS application, but If you were using the VFD to control motor speed, then I suppose your control signal would go into this low voltage signal input? Its not just on/off, its variable 0-12V, 4-20mA, 0-24, etc? I've designed some industrial DC systems with VFDs, but I'm mechanical and haven't gotten into the details of which wire goes where. I may not "need" to know it, but I sure like having an understanding so I'm not completely lost when the electricals are talking.

Mike

For variable speed on the FM50 you can use the key pad to vary the frequency OR it has inputs to use a 10Kohm pot. This circuit is a 10V circuit seperate from the on/off/reverse circuit.

[Jerome Stanek]

If you use a roto phase you can run multiple machines from it and you can use your mag switch as before. We just put a sub panel in and run cicuits to each machine.

[Kevin W Johnson]

If you use a roto phase you can run multiple machines from it and you can use your mag switch as before. We just put a sub panel in and run cicuits to each machine.

Both ways have pro's and con's. Depending on the equipment being used though (ie. bandsaws, lathes, drill presses), having the variable speed that comes with having a VFD is really nice.

[Van Huskey]

Both ways have pro's and con's. Depending on the equipment being used though (ie. bandsaws, lathes, drill presses), having the variable speed that comes with having a VFD is really nice.

Don't forget soft start, motor braking and reversing(lathes and mills).

[mreza Salav]

Ok, I have ordered the one from Factorymation and it's on its way to me.
Now reading another thread, I came across the following post by Rick which makes me worrried:

http://www.sawmillcreek.org/showthread.php?187472-16-quot-jointer&p=1938527#post1938527

The manual for my bandsaw does say that it has a motor brake which makes it stop within 10 seconds. The saw has a foot brake too but as far as I have checked it there is no micro-switch, just a drum type brake (at the back of lower wheel). Is the VFD going to work with this 3-phase motor?!