VFD vs Staticv Phase converter

[Matt Day]

Gaines,
My woodworking machines have all worked fine, and many hundreds of others have too. For instance, the motor in this application likely has an Amp rating of around 8, and the FM50 has an FLA of 10.5. The FLA need only be equal or higher than the motor plate amperage. The OP will be fine and does NOT need a 5hp VFD.

Pumps are different. Watch the video in the link below for a good overview.
http://www.vfds.com/blog/vfd-buying-guide

PS, I'm no expert, this is knoweledge I've gleaned from more knowledgeable folks than I.

[Van Huskey]

Gaines,
My woodworking machines have all worked fine, and many hundreds of others have too. For instance, the motor in this application likely has an Amp rating of around 8, and the FM50 has an FLA of 10.5. The FLA need only be equal or higher than the motor plate amperage. The OP will be fine and does NOT need a 5hp VFD.

Pumps are different. Watch the video in the link below for a good overview.
http://www.vfds.com/blog/vfd-buying-guide

PS, I'm no expert, this is knoweledge I've gleaned from more knowledgeable folks than I.

I agree, no de-rating for our machines. Whether larger or 24-7 motors need to have the VFD de-rated I don't know but as you said there are thousands of woodworking and metal working machines being run by ts hobbyists with no de-rating.

[Erik Manchester]

I have a 3 hp Unisaw that I ran on a Teco FM 50-203C without any issues, and it was handy for soft starts and deceleration. Don't want to set too rapid a deceleration as one could spin the arbor nut off. I think mine was set for 3 secs.

in my case, I had the VFD mounted on the shop wall some 15' from the saw with a start/stop station at the saw. You want to put the VFD in an enclosure with adequate ventilation but well clear of the sawdust being produced by the saw or other machines.

[fRED mCnEILL]

Given that my saw is 3HP would this VFD do the job.

https://www.amazon.com/LAPOND-Invert...E+VFD+Inverter

Thx

Fred

[Matt Day]

Looks like it would work fine. I haven't seen that one before but I might look into it for my Unisaw. Comes with a speed pot which is usually extra. Might be a winner there!

Just note that the only negative reviews were all about setup and wiring. One did however say the manufacturer was helpful.

[Erik Manchester]

Fred, that drive will do the job as well as the Teco FM50, however, the instructions for Asian VFD programming are notoriously poor and may leave one stretching their head if new to VFDs. All you would be doing is using it for phase conversion so the programming is simple, basically just entering motor parameters, and setting up the controls.

There are many YouTube examples of the FM50, perhaps less so with this one you are looking at. Teco provides a warranty and good support, but these newer asian VFDs are very reliable in my personal experience so hopefully not a factor. For that price you can buy two just to have a spare available. Once you figure out the configuration, write it down in case you have to replace it 18 months later, though that is unlikely.

[Dan Friedrichs]

I agree with Erik - that one looks identical to the "ebay special" I posted, earlier (but costs a bit more). It would be a bit of a challenge to program, and on a table saw, the speed adjustment likely wouldn't be very useful.

[Dave Cav]

I'm running two table saws, an 18" thickness planer, a tenoner, a mortiser and a drill press on individual VFDs. No problems and no derating of the motor. You can, however, sometimes derate the VFD. I'm running a 5 HP table saw on a 3 HP VFD. It all depends on the power requirements of the tool. On the other hand, my thickness planer, which also has a 5 HP motor, requires a 7.5 HP VFD to operate satisfactorily.

[Matt Day]

Dave, regarding the planer, I'm guessing it pulls a lot of amps so you had to step up the VFD size?

[David Kumm]

Jack Forsberg over at Canadian woodworking sells vfds and will program them to your motor. His prices are good. Dave

[Dave Cav]

Dave, regarding the planer, I'm guessing it pulls a lot of amps so you had to step up the VFD size?

Yes. The table saw with the 5HP motor is a Delta 12/14 and seldom if ever pulls anywhere near FLA, so I was able to successfully use a 3HP VFD with it. The planer is a helical head PM 180 and has a lot more going on under the hood, since both the cutterhead and the feed works are all powered off the same motor. Before I purchased the VFD I discussed it with the tech rep at Factorymation and he strongly suggested the 7.5 HP VFD, which has worked great for me. Still, despite the oversized VFD, I have managed to trip it on over current a couple of times when taking too heavy a cut with too fast a feed speed.

[Matt Mattingley]

Sizing a VFD for phase conversion boils down to current (amps). When going from a single phase input to three phase out put you will need the drive to be capable of putting out 1.73 times the motor nameplate amps. You roughly de-rate the drive by half. I work in the electrical field and we routinely put VFDs on three phase irrigation motors where only single phase power is available. They do not work unless properly de-rated. I suppose one exception would be a motor that isn't under a load and therefore not pulling anywhere close to its nameplate amps. Once a load is applied the drive would likely trip/fault if not sized correctly.

Yep you hit the nail on the head dead nuts,

The planer is a helical head PM 180 and has a lot more going on under the hood, since both the cutterhead and the feed works are all powered off the same motor. Before I purchased the VFD I discussed it with the tech rep at Factorymation and he strongly suggested the 7.5 HP VFD, which has worked great for me. Still, despite the oversized VFD, I have managed to trip it on over current a couple of times when taking too heavy a cut with too fast a feed speed.

In your situation buying a 7.5 hp three-phase VFD and only giving it a single phase power, it is D rated. 7.5÷1.73 equals 4.33 hp. You'll never overload your motor using that VFD, but you'll never truly reach the motor/machines potential. Technically the sales guy should've told you (maybe he did) this and you probably should've bought the 10 hp three-phase VFD and given it single phase power which would've given you a possibility of 5.78 hp. Been through the VFD you could have set maximum amperage out/ horsepower to be 8.65 hp. This would keep your output geared to your motor.

I also suggest you to touch base with Jack Forsberg.

Based on your title, VFD versus static converter, A static converter will only provide you three phase for start up then it only runs on single phase. This is a lot like having a three cylinder car engine only giving you power from two cylinders. This is called the D rating. A static converter is always the D rated! So if you buy a static converter, it will always be 3hp ÷1.73 equals 1.73hp. So Using a static phase converter on a 3 hp motor will end up being a 1.73 hp motor. No if and or butts! A static converter can only provide a motor 58% of its potential. A three phase VFD Fed single phase has the same problem! Except, if you overload a three phase D rated VFD it will trip like a breaker. If you overload a static phase converter, you could burn out the motor. A properly married VFD can have a potentiometer for speed control, breaking that will blow your mind, sensor less vector control, you can run numerous motors... using the same VFD powering the same machine. If you have a two Motor planer, You can size the VFD to start both. If you had five motor line shaper you can run all the motors with one VFD. There Single phase to 3 phase VFD's on the market that are not D rated. I have four of them running my shop. I'm waiting for the break resistor to go on the 18 inch table saw blade. Just imagine an 18 inch table saw blade coming to a stop in two seconds from 3600 RPM.

[Dan Friedrichs]

In your situation buying a 7.5 hp three-phase VFD and only giving it a single phase power, it is D rated. 7.5÷1.73 equals 4.33 hp. You'll never overload your motor using that VFD, but you'll never truly reach the motor/machines potential. Technically the sales guy should've told you (maybe he did) this and you probably should've bought the 10 hp three-phase VFD and given it single phase power which would've given you a possibility of 5.78 hp. Been through the VFD you could have set maximum amperage out/ horsepower to be 8.65 hp. This would keep your output geared to your motor.

Uhh...what?

I assume he has a 3-phase motor on the table saw, not a single phase motor....

Your whole post made no sense at all...

[David Kumm]

Matt's post makes perfect sense assuming that almost all vfd's rated larger than 5 hp are 3 phase input so they need to be twice the motor size to function under single phase input . A 3 phase input 7.5 hp rated vfd is slightly undersized for a 5 hp motor at full load. Doesn't matter most of the time but the larger vfd will be needed for planers, sanders, shapers and dust collectors. Not so much for saws. Dave

[Matt Mattingley]

Uhh...what?

I assume he has a 3-phase motor on the table saw, not a single phase motor....

Your whole post made no sense at all...

I assume you did read what I wrote below that quote??? And understand. Yes,no???

I was quoting two different situations and trying to help out in in-depth context. I made a couple edits to my post and I will clarify if clarification is required. Some people don't understand three-phase motors. Some people don't understand VFD's, RPC's, SPC to jump from single phase to three phase. I understand this thread to a Tee. Some might not want my knowledge. Some may only want to stay with single phase the rest of their life. I don't care which way you want to go, I personally just like to get machines working. Enjoy and have fun and make a living. Maybe I'm speaking in a language that most don't understand. I'm OK with educating, if you are willing listen. I'm even OK with you (or anyone) disputing anything I say! I'll even put up a shop videos!