VFD For 3 Phase Equipment, not just motor

[John Halsted]

I'm looking at a Felder AD941 that is a 3-phase machine. I'm wondering if I can just put a VFD in front of the whole machine, or if VFD's are really only designed for handling one motor. The machine has peripheral electronics like the power planer bed height and digital readout. I do not know if the feed motors are separate or if everything runs off of one motor.

There don't seem to be many "digital phase converters" on ebay, just expensive rotary stuff. But when I search for VFD there are tons of cheap options. I don't see any reason why a VFD couldn't do what needs to be done, unless they're only setup to operate in a load-sensing way where it only works powering a motor directly.

This exact question about the AD941 was actually asked in an older thread but never clearly answered and the OP never came back and said what he did, if anything. The answer would apply to any 3 phase equipment though.

Edit: AD941, not 741 and not 471, woops.

[ray grundhoefer]

A vfd is only meant to be used with an individual motor. I believe It would cause all kinds of problems with your electronics. In this instance a rotary phase convertor is probably your best option.
Ive never done it but its not to hard to make your own with a 3 phase motor. You can probably find out how on youtube.

[John Halsted]

A vfd is only meant to be used with an individual motor. I believe It would cause all kinds of problems with your electronics. In this instance a rotary phase convertor is probably your best option.
Ive never done it but its not to hard to make your own with a 3 phase motor. You can probably find out how on youtube.

I still can't quite understand why a vfd shouldn't be able to act as a dumb phase converter, but let's say that's the case. The next quest is can the Felder AD 941 be setup with a vfd on the cutter motor and a single phase to handle the powered bed and digital readout? I still don't know if there is an independent drive motor for the planer feed.

A vfd would be far cheaper and smaller than a rotary phase converter.

[jack forsberg]

We Have wired your saw with a single VFD a few times . You cannot think of VFD’s as a power source to plug in to. they are motor controls and have to be wired as such. Generally we leave your three phase controls in tact on your saw and run new control wire for the vfd . It is obviously the best to have two VFD’s but just for the scoring saw it’s not a big deal. If you’re interested in our solutions contact me at Jack@jforsberg.ca . All we need from you is a picture of the motor tags

[Van Huskey]

We Have wired your saw with a single VFD a few times . You cannot think of VFD’s as a power source to plug in to. they are motor controls and have to be wired as such. Generally we leave your three phase controls in tact on your saw and run new control wire for the vfd . It is obviously the best to have two VFD’s but just for the scoring saw it’s not a big deal. If you’re interested in our solutions contact me at Jack@jforsberg.ca . All we need from you is a picture of the motor tags

Jack since it is potentially relevant here (since the J/P in question is available with motors up to 10hp) what is the limit on HP (or kW) for single phase in 3 phase out VFDs currently?

[jack forsberg]

Jack since it is potentially relevant here (since the J/P in question is available with motors up to 10hp) what is the limit on HP (or kW) for single phase in 3 phase out VFDs currently?
Currently up to 20 hp 39 amps Three phase out put. but do understand that this requires a 100 amp branch circuit. This VFD is a particularly large at 44 lbs and shipping costs are in the $120 range.

[David Kumm]

There were Felder combo machines sold as single phase that had three phase motors controlled by a vfd and wired internally to handle the various electronics. I'm guessing that what Jack does is similar. Felder used small motors so the vfd could fit inside the machine. Dave

[Malcolm McLeod]

Simply put, VFDs take the input AC (assuming 240VAC, 1ph for you), convert is to DC and use it to charge it's internal DC buss (2 ea. - 1 DC+ / 1 DC-). Then the output section of the VFD rapidly switches the DC buss on and off - injecting what 'looks' like 240VAC, 3ph onto the motor leads. ...not sure this matters to you, but sometimes I just can't resist data vomit.:o

So in your proposed setup, you power the VFD, and hit 'Run'. It ramps the output electronics to the Hz setting you selected (lets say 60Hz, so full 240VAC). There is absolutely no load on the VFD at this point. Now you go to the Felder, hit the 'go' button for the ?4Hp? saw motor, the Felder starter closes, and the full ampere load hits the VFD. The saw blade twitches briefly and you need a new VFD.

A VFD must be connected directly to the motor with NO switch gear, disconnects, or starters in between. Please don't try what you're proposing. Hope this helps.

...And see what Jack posted. I think what he's saying is they leave the Felder controls 'ON' all the time, then use the VFD controls to 'Start' the saw..? This avoids the magic smoke release. But don't let me put words in his mouth.

Van, I've never seen VFDs claim to handle >5Hp, 3ph motors using 1-ph input power. But nearly, any VFD can serve as a 'converter', IF the input section can handle the amps associated with the 1-ph current draw of the load and can have the "input phase loss" alarm disabled. Just don't shock load it like I described above. And they get really pricey for the average hobbyist!

[Dan Friedrichs]

John,

There is nothing physically which prevents a VFD from acting as a "power source" rather than a "motor controller". The VFD rectifies the single-phase input to DC, then chops it back up (inverts it) to produce 3-phase AC. It could easily do that and operate as you desire. However, no one (aside from you) has that "need" - the large-scale need is to control a motor's speed and provide overcurrent protection. So while a VFD could conceivably be produced to do what you desire, I think it either doesn't exist (commercially), or would be so expensive (due to being such a niche product) that it would be cost-prohibitive.

If you're somewhat electrically-inclined, I'd suggest you do a little disassembly of the machine and see if you can figure how the electronics are powered. I'd bet there is a AC-to-DC power supply in there generating 12V or 24V for the electronics and elevation motor(s). If so, that power supply is almost certainly "universal" input, and single-phase input (you can connect 90-264VAC into it, meaning it would run on 120V single phase, 240v single phase, or from 2 legs of a 3 phase supply, etc).

Best case, you might find that you can power the digi-drive electronics from single-phase with zero modification, then put a VFD on the main motor.

(Jack - the machine the OP is talking about is a jointer/planer, not a saw, so there is no scoring blade motor...)

[John Halsted]

The AD 941 jointer/planer I'm looking at is 4hp.

Malcolm, from your explanation it sounds like you're saying VFD's are undersized or overrated for their labeled motor hp, and the way they can get away with this is by soft starting the motor, thereby skipping the high-draw moments of the starting sequence. Ok fine, but then I I should just be able to get a much bigger VFD, right? Even one rated for 10hp is only $200.

[Van Huskey]

I hadn't seen more than 5hp rating for a 1>3ph VFD but I had heard Jack had options for more, apparently a lot more. Not surprised about the amperage necessary for a 20hp drive, I think most 20hp (starting) RPCs need even more than 100 amp service.

[John Halsted]

John,

There is nothing physically which prevents a VFD from acting as a "power source" rather than a "motor controller". The VFD rectifies the single-phase input to DC, then chops it back up (inverts it) to produce 3-phase AC. It could easily do that and operate as you desire. However, no one (aside from you) has that "need" - the large-scale need is to control a motor's speed and provide overcurrent protection. So while a VFD could conceivably be produced to do what you desire, I think it either doesn't exist (commercially), or would be so expensive (due to being such a niche product) that it would be cost-prohibitive.

If you're somewhat electrically-inclined, I'd suggest you do a little disassembly of the machine and see if you can figure how the electronics are powered. I'd bet there is a AC-to-DC power supply in there generating 12V or 24V for the electronics and elevation motor(s). If so, that power supply is almost certainly "universal" input, and single-phase input (you can connect 90-264VAC into it, meaning it would run on 120V single phase, 240v single phase, or from 2 legs of a 3 phase supply, etc).

Best case, you might find that you can power the digi-drive electronics from single-phase with zero modification, then put a VFD on the main motor.

(Jack - the machine the OP is talking about is a jointer/planer, not a saw, so there is no scoring blade motor...)


All of that makes sense, except that since VFD's are programmable, I don't see why designers wouldn't include a "dumb converter" mode. As far as demand, people do sell and want phase converters - why is anyone using rotary anymore when the hardware needed to do it solid state is so cheap?

I'm actually an electrical engineer, so I am inclined to rewire the machine. I just wish I knew a bit more about what needed to be done before buying it.

Any AD941 owners here that can look under the hood and tell me what it's got?

[jack forsberg]

Simply put, VFDs take the input AC (assuming 240VAC, 1ph for you), convert is to DC and use it to charge it's internal DC buss (2 ea. - 1 DC+ / 1 DC-). Then the output section of the VFD rapidly switches the DC buss on and off - injecting what 'looks' like 240VAC, 3ph onto the motor leads. ...not sure this matters to you, but sometimes I just can't resist data vomit.:o

So in your proposed setup, you power the VFD, and hit 'Run'. It ramps the output electronics to the Hz setting you selected (lets say 60Hz, so full 240VAC). There is absolutely no load on the VFD at this point. Now you go to the Felder, hit the 'go' button for the ?4Hp? saw motor, the Felder starter closes, and the full ampere load hits the VFD. The saw blade twitches briefly and you need a new VFD.

A VFD must be connected directly to the motor with NO switch gear, disconnects, or starters in between. Please don't try what you're proposing. Hope this helps.

...And see what Jack posted. I think what he's saying is they leave the Felder controls 'ON' all the time, then use the VFD controls to 'Start' the saw..? This avoids the magic smoke release. But don't let me put words in his mouth.

Van, I've never seen VFDs claim to handle >5Hp, 3ph motors using 1-ph input power. But nearly, any VFD can serve as a 'converter', IF the input section can handle the amps associated with the 1-ph current draw of the load and can have the "input phase loss" alarm disabled. Just don't shock load it like I described above. And they get really pricey for the average hobbyist! no generally we leave the old motor controls in tact but do not use them this is only so the Machine can be converted back to a three phase with little work . There is actually no problems with my drives bringing Motor’s online as long as the VFD is sized properly. It’s more prudent to start both motors at the same time as disconnecting the motor is not as harsh . Overload is a little more complicated but not impossible. Generally what prohibits this type of installation is the larger VFD’s get the more expensive. generally two smaller ones are cheaper. If you’re looking for generated electronic inverter electricity phase perfect is the way to go. Basically a VFD without variable frequency. Although I feel I can provide far more horsepower with individual VFD’s and you’re not reliant on one power source and therefore cannot have a catastrophic failure.

[David Kumm]

John, are you sure the motor isn't 4 kw rather than 4 hp? Felder generally spec'd their single phase motors at 4 hp and the smallest three phase was 4 kw or 5.5 hp. Dave

[Malcolm McLeod]

The AD 941 jointer/planer I'm looking at is 4hp.

Malcolm, from your explanation it sounds like you're saying VFD's are undersized or overrated for their labeled motor hp, and the way they can get away with this is by soft starting the motor, thereby skipping the high-draw moments of the starting sequence. Ok fine, but then I I should just be able to get a much bigger VFD, right? Even one rated for 10hp is only $200.

Again, simply put - you are correct. VFDs can be under-sized, compared to line starters, because of the relative soft start. But the devil is in the details:
- What is the 1-ph FLA for your 4Hp motor? This is approx 1.7 times greater than the nameplate. A VFD must have its input sized so that each input leg can support this current.
- Make sure you have a start scheme that avoids the high in-rush of a line starter. My guess is you'd smoke even the 10hp in the scheme I outlined above.
- If the VFD doesn't support disabling the phase loss alarm, it just sits there 'faulted' and won't run.

[Ron Boulton]

Malcolm is correct. It is not good ( Very Bad?) practice to disconnect, or connect, the load from a VFD while the VFD is powered up. Sure fire way to destroy the VFD. This is what will happen if you use the normal controls on the AD941.
Only option is to leave the VFD permanently connected to the motor in the Felder AD941 and rewire the control on the Felder AD941 to switch the VFD as suggested by Jack.

Really the best option is a suitably sized Rotary Converter. If you oversize the RC you can also use it for other 3Phase machines that might become available

By the way a Felder AD 941 is a Planer /Thicknesser not a Saw
Ron

[jack forsberg]

I hadn't seen more than 5hp rating for a 1>3ph VFD but I had heard Jack had options for more, apparently a lot more. Not surprised about the amperage necessary for a 20hp drive, I think most 20hp (starting) RPCs need even more than 100 amp service. actually only 90 A but most people can’t find a breaker that size . I see some people here are still talking about the reading and puts on three phase VFD’s. Mine are Custom made with front end is large enough for single phase input But more importantly parameters are for single phase So there’s no little tricks like disabling phase loss.

[Dan Friedrichs]

All of that makes sense, except that since VFD's are programmable, I don't see why designers wouldn't include a "dumb converter" mode. As far as demand, people do sell and want phase converters - why is anyone using rotary anymore when the hardware needed to do it solid state is so cheap?



I suppose they could (and FWIW, I'm an EE who works in power electronics...). To be honest, I'm not sure why they don't exist.

I don't think the feed rollers have separate motor(s). So you really only have the main motor and the electronics. The electronics are also certainly DC, so there must be a power supply in there. That power supply is almost certainly single-phase (although it may just be wired to 2 legs of the 3-phase supply).

I'd encourage you to go for it. I don't think the problem is that daunting.

Absolute worst-case, you buy/build an RPC.

[John Halsted]

John, are you sure the motor isn't 4 kw rather than 4 hp? Felder generally spec'd their single phase motors at 4 hp and the smallest three phase was 4 kw or 5.5 hp. Dave

You almost got me, had to go back and double check myself, but yes it is 4hp, not 4kw.

[Dan Friedrichs]

actually only 90 A but most people can’t find a breaker that size . I see some people here are still talking about the reading and puts on three phase VFD’s. Mine are Custom made with front end is large enough for single phase input But more importantly parameters are for single phase So there’s no little tricks like disabling phase loss.

Jack, I'd be curious to hear more about this. How are you getting "custom made" VFDs for what appears to be a hobby business? And what does "parameters..for single phase" mean (are you just saying that the input rectifier is sized for a single-phase input?). I'm genuinely curious, as my professional life has me buying electronics, and I sure can't get custom power converters made at quantities in the hundreds (or even thousands) of units/year...

I would think the regulatory hurdles associated with certifying and safety testing a custom design for on-line connection would require a fairly sizable investment...

[John Halsted]

I suppose they could (and FWIW, I'm an EE who works in power electronics...). To be honest, I'm not sure why they don't exist.

I don't think the feed rollers have separate motor(s). So you really only have the main motor and the electronics. The electronics are also certainly DC, so there must be a power supply in there. That power supply is almost certainly single-phase (although it may just be wired to 2 legs of the 3-phase supply).

I'd encourage you to go for it. I don't think the problem is that daunting.

Absolute worst-case, you buy/build an RPC.


I'd concluded about the same and I'm going to take this as the winning answer. If I get a good deal on the 3 phase 941 there are a few routes of attack to solve the power problem, the most expensive of them being a rotary converter which may very well be useful for other things. Though as someone who also has done a lot of fairly recent power electronics design, I still feel silly using a mechanical spinning thing to do what can now easily be done solid state.

I'll see what I can get it for. In the meantime if anyone had a 941 (or 951) and feels like jumbling around inside and telling me how it's wired, that'd be great.

[jack forsberg]

I'd concluded about the same and I'm going to take this as the winning answer. If I get a good deal on the 3 phase 941 there are a few routes of attack to solve the power problem, the most expensive of them being a rotary converter which may very well be useful for other things. Though as someone who also has done a lot of fairly recent power electronics design, I still feel silly using a mechanical spinning thing to do what can now easily be done solid state.

I'll see what I can get it for. In the meantime if anyone had a 941 (or 951) and feels like jumbling around inside and telling me how it's wired, that'd be great. I’d rather not share my bussness connections with the manufacture nor do I think it’s Any of your concern. Parameters are for single phase Input drive And are relevant to their particulars. I wouldn’t worry about me too much As I can’t see someone like you ever buying my VFDs

[Malcolm McLeod]

actually only 90 A but most people canÂ’t find a breaker that size . I see some people here are still talking about the reading and puts on three phase VFDÂ’s. Mine are Custom made with front end is large enough for single phase input But more importantly parameters are for single phase So thereÂ’s no little tricks like disabling phase loss.

Sounds like a slick set-up (i.e. you've taken the devils out). I try to keep up because of my shop, but not much time lately.

I deal with larger VFDs in the industrial world (last 2 weeks was commissioning of 4 x 150Hp + 1 x 400Hp + 300 I/O + PLC). We've got about 30 of these setups in the next year. In about 6 weeks or so, we shift efforts to the big ones (>2000Hp). ...Not much 1-phase stuff out here. :)

[Van Huskey]

the most expensive of them being a rotary converter which may very well be useful for other things.

Check out Phase Perfect for a step up from RPCs in price. Speaking of Phase Perfect most people I know with 3ph WWing machines run something similar to the American Rotary AD series BUT my 3ph machines are dumb (pretty much the only electrical things I own that aren't smarter than me), I have gotten the impression that modern Euro machines need or might benefit from the higher level RPCs with better balance and voltage stability. However, if Dan is correct and they are using rectified DC for the brains it might not be an issue. Anyone care to comment?

As for the RPC what I like about them is how simple they are and how enticing they make further 3ph purchases. Once you run your 3ph circuits you just plug the newly acquired 3ph machine in and spins like it is designed to. No need to add the extra cost of a VFD to the cost benefit analysis, but you do lose the cool feature set of a VFD.

Stepping back to the question of why no dumb VFDs I can only assume that there is little or no price benefit to producing them. Look at some of the multimeters like Fluke, often the boards are the same on lower level units compared to next couple of models up and people are learning to "hack" them to get the higher model's features. It is cheaper for Fluke to just disable the features but put them in a different case vs building boards without the features.

Also, Jack I doubt Dan meant any offense at all nor did he want to dissect your business or circumvent your connection. My guess is he was simply intrigued. As for the single phase parameters, it might well be a language gap much like attorneys degreed engineers often speak in their own language and use lots of terms of art. I just don't want the thread to go wonky as it is interesting and should be full of information for the future.

[jack forsberg]

Sounds like a slick set-up (i.e. you've taken the devils out). I try to keep up because of my shop, but not much time lately.

I deal with larger VFDs in the industrial world (last 2 weeks was commissioning of 4 x 150Hp + 1 x 400Hp + 300 I/O + PLC). We've got about 30 of these setups in the next year. In about 6 weeks or so, we shift efforts to the big ones (>2000Hp). ...Not much 1-phase stuff out here. :)

Those must be the size the lockers. Really trying to feed the market of those trying to operate three-phase machinery from household so that limits us to about 40 hp drives. Most people are just simply confused as to what drive to get and how to wire the controls and set parameters. We have a system of walking you through step-by-step regardless your experience. We make it so easy monkey could do it. lol

[jack forsberg]

Also, Jack I doubt Dan meant any offense at all nor did he want to dissect your business or circumvent your connection. My guess is he was simply intrigued. As for the single phase parameters, it might well be a language gap much like attorneys degreed engineers often speak in their own language and use lots of terms of art. I just don't want the thread to go wonky as it is interesting and should be full of information for the future.All good I wouldn’t worry too much about it we only sell about 300 units a year to the United States

[Matt Mattingley]

It has already clarified (and I’m not trying to beat a dead horse but...).
1 Hp = 0.745 hp or... 1 kw = 1.34 hp. And you always want your feed line/branch distribution to be 20% bigger. I Believe this is required under the NEC.

If a Single phase VFD has output of 40 A, you multiply this by 1.73 then add 20%. By my calculator shows 83 A. This would take it to the next breaker size which is 90 A and feedline adequate. A feed line should be 125% of device load or to a maximum of 250% if properly distributed with fusing.

-SPC (or Static phase converter) do their job at starting a three phase motor, but once started only have 2/3 of the nameplate power. You are single phasing a three phase motor. This is the cheapest solution.


-VFD (or variable frequency drive) these are generally designed to run one motor at a time (but are not exclusive). A Vfd can run two or three motors… Vfd’s can be specifically set up for single phase or three phase input. The beauty is is they are fairly cheap and... if you only have two or three machines or you’re looking for variable speed, Soft start, breaking... multiple station controls and a array of sensor commands. A Vfd could be beneficial for not just conversion. Generally the second cheapest but wiring is required. Of course this is AC to DC back to AC pulse wave modulation and some pretty high-tech computer programming behind it.

-RPC (or rotary phase converter) is the good old bulletproof way that farmers have been doing it for 50 years. Electrical companies even longer. Very few moving parts, A few capacitors for starting a few capacitors for balancing and a few heavy contacters... you don’t need to be to brilliant to keep this up and running. You need a good test metre and you need to check your system a few times a year. The nice part about this system is... with a proper set up you can step up the voltages. The problem with the system compared to the PP or VFD’s is there a waste electrical power through heat and mechanical mass while running in idle. Usually about 2 to 3 kW per hour. What do you pay for a kilowatt hour??? Are you really worried about $.18 per hour(or whatever you pay), Times two or three???

-PP (Phase Perfect) is the cream of the crop. Initial cost is about $3000. This system allows for the two single phase natural lines to be completely passed through the device and it uses hall current measuring devices and creates pulse wave modulation at 208 V to ground perfectly no matter the amperage to the third leg (or generated leg, similar to an RPC but, not in a wild form). This system can be sent through transformers similar to RPC’s to step up the voltages but they generate a cleaner/more consistent third leg.

Both RPCs and PP’s you need to be concerned with contactors/Transformers in a machine to not receive the 120/208 improperly. This is a Delta/Wye situation. Any EE, E technologist or industrial electrician can walk you through this kind of situation if it applies to you.

I presently run...
1=> 5 hp RPC with the transformer to suit my needs.
1=> 20 hp homemade RPC with a transformer to suit my needs.
My Air compressor, Lathe, Tablesaw, 2 Drill press’s (and soon my ventilation hood) are all run by single phase VFD‘s. The crazy part is my air compressor has 4 different speeds depending on my demand for air. I have different pressure sensors for different call commands to the VFD through the parameter settings. Just remember you don’t need an engineer to set these things up.

Yes the PP would be great.... but I am just like the good old farmer. Technology is going to get pretty advanced and I hope to keep up.... I have a single phase 243 V fed property. I have 240 V three-phase and 600 V three-phase. Vfd’s have been a good compromise (in my opinion) for my needs.

My opinions are just my opinions and are open to any questioning. Sure there’s a lot to think of..... and there’s a brilliant brains here to help you choose your best solution. Sift through them to best suit your needs.

[John Halsted]

You almost got me, had to go back and double check myself, but yes it is 4hp, not 4kw.

Hah! The seller actually got it wrong when he said 4hp. Nameplate on the machine says 4kw.

[Bill Dufour]

Seems like two VFDs might work one constant HZ for the low power stuff, with a big load reactor. I assume the low power controls are intermitant use only. And a separate one to only run the main motor using low voltage controls direct to the vfd.
My 3Hp lathe came with 1hp VFD which worked fine for light loads. It just means the motor can only supply 1hp. As long as the vfd can supply enough power to run the motor at idle it should be able to do some work.
Obviously Tesla has figured out how to make VFD run off of a dc supply direct to the dc buss. Several hundred horsepower of vfd there. I think all the other motors are standard 12volt dc?
Bill D.
Bill D

[Bill Dufour]

I wonder how prices are getting on solar inverters that make ac from dc? you could just throw a bridge rectifier in to supply it with 180 volts dc from your house single phase supply.
Bil lD.

[Matt Mattingley]

Hah! The seller actually got it wrong when he said 4hp. Nameplate on the machine says 4kw.
So it looks like you got yourself a 5.36 horse power machine. Or you just got yourself a 4 hp machine. I’m with Dave above. I have a hammer machine which is built by felder and it only has 4 hp. Do you have any pictures of the motor name plates? Maybe you did luck out and you got the 5.5 hp. Any pictures of the machine???

[Van Huskey]

I think all the other motors are standard 12volt dc?
Bill D.
Bill D

I think both the small and large motors are rated at 320v. The battery voltage varies depending on the spec of the car but the highest rated production pack is ~400v max and 370v nominal. Max current delivery from the batteries is about 1500 amps. If the motors were 12v the current would melt railroad rail, hyperbolic but you get the picture.

As for the drives they output 3ph AC to the motors. When you press the accelerator they increase the frequency so the magnetic field is moving faster than the current rotor speed and thus speeds the motor up, when you press the brakes it reduces the frequency so the magnetic field is slower than the rotor and you get regen braking.

[Darcy Warner]

My last RPC before I got real pole power was all solid state controls. Made by a small electric motor shop in farm an Amish country. Best unit I ever ran.

[Rod Sheridan]

The AD941 if it 3 phase will use single phase power for the electronics and the table elevation motor. ( the elevation motor is actually DC and runs from the control power).

To run the machine from a single phase source you would mount the VFD on the machine.

I would feed the VFD from the motor contactor, in case the motor has thermal limit switches which are used to drop out the motor.

Regards, Rod.

[jack forsberg]

The AD941 if it 3 phase will use single phase power for the electronics and the table elevation motor. ( the elevation motor is actually DC and runs from the control power).

To run the machine from a single phase source you would mount the VFD on the machine.

I would feed the VFD from the motor contactor, in case the motor has thermal limit switches which are used to drop out the motor.

Regards, Rod.Rod are the thermal overload’s on the motor not accessible to feed the VFD control side.Not that it would be necessary to even use them. But I think what you’re saying is they may send faults so you’d want them disabled at minimal no ?

[Rod Sheridan]

Jack, if they are in the machine you could indeed wire them to the VFD in the manner of an interlock.

I would leave them connected to the starter however as it would be simpler.

regards, Rod.

[jack forsberg]

Jack, if they are in the machine you could indeed wire them to the VFD in the manner of an interlock.

I would leave them connected to the starter however as it would be simpler.

regards, Rod.That’s what I thought you’re thinking might be. The only for seeable problem I can see Is the VFD will not have any stop command for breaking.

[Bill Dufour]

I think both the small and large motors are rated at 320v. The battery voltage varies depending on the spec of the car but the highest rated production pack is ~400v max and 370v nominal. Max current delivery from the batteries is about 1500 amps. If the motors were 12v the current would melt railroad rail, hyperbolic but you get the picture.

As for the drives they output 3ph AC to the motors. When you press the accelerator they increase the frequency so the magnetic field is moving faster than the current rotor speed and thus speeds the motor up, when you press the brakes it reduces the frequency so the magnetic field is slower than the rotor and you get regen braking.

I bet the smaller motors are not 370 volts. Wires in the door hinge areas brake enough that I would not want 370 volts there.
Bill D.
I

[Van Huskey]

I bet the smaller motors are not 370 volts. Wires in the door hinge areas brake enough that I would not want 370 volts there.
Bill D.
I

I completely missed what you were saying, specifically, I excluded the word "other" when I read your post. I thought you were saying that all the Telas motors run at 12v which would require ungodly current. When I said small and large motors I was referencing the two sizes of drive motors they use, not the miniature motors like HVAC fans, window lift and seat movement motors, they are indeed on a seperate low voltage DC buss. I get what you are saying now.

[Bill Dufour]

I completely missed what you were saying, specifically, I excluded the word "other" when I read your post. I thought you were saying that all the Telas motors run at 12v which would require ungodly current. When I said small and large motors I was referencing the two sizes of drive motors they use, not the miniature motors like HVAC fans, window lift and seat movement motors, they are indeed on a seperate low voltage DC buss. I get what you are saying now.
Makes sense now. I did not realize they had different size drive motors on the same car. I have read the GEM cars, remember them at costco?, use bigger motors if you pay extra. There is a aftermarket selling the upgraded GEM motors. I have to wonder if the controller and wiring can handle them. But hotrodders just add more horsepower until things break.
Bill D.

[Bill Dufour]

I read the super chargers supply 400 volts DC at 400 amps and bypass all the battery protection circuitry to do it. So 370 volts for the drive motors make sense I guess.
I have read that Diesel vehicles use a vacuum pump to make engine vacuum to run all the little vacuum actuators under the dash for the heating/cooling system. I had a neighor who had one of the first Cadillacs with power windows . they used a hydraulic system which had problems.
Bill D

[Van Huskey]

I did not realize they had different size drive motors on the same car.
Bill D.

I don't want to continue to jack this thread but will address this quickly. On the older one motor cars they used a larger and smaller motor depending on if it was a standard or performance model. Now they make dual motor cars and on the standard models both motors are the same and on the performance versions, the rear is bigger than the front. This gives it a rear wheel torque bias similar to most every AWD performance car.

[Alan Lightstone]

OK. I'm involved with two parts of this thread.

1.) Van is right regarding the two separate motor sizes on the Tesla Model S cars with the D designation (for instance, mine is a P85D, with dual motors (and 690hp), and the ludicrous mode upgrade with a smaller motor in front, and a larger motor in the rear. I get 0-60 in 2.8 seconds, and you almost pass out when flooring it. So I assume that with a larger battery in the P100D, you may actually pass out from the g-forces (not sure if that's a sensible upgrade). The ludicrous mode upgrade uses a rare-earth metal bus to handle the higher currents required for the ludicrous, not just insane acceleration.

2.) I've got a Felder A941 Planer with a 3-Phase 5kW (6.7 hp) motor, a D951 Thicknesser with a 3-Phase 4kW (5.4hp) motor, and an FB710 Bandsaw with a 3-Phase 5.5kW (7.4 hp) motor on order, that will be delivered in September. The planer and the thicknesser both have digital electronics, so I've got power concerns with them also. I'm planning on getting a Phase Perfect unit. I have a large solar array, and am tempted to have the power company bring 3-phase power to the workshop, but the engineers will have a heart attack figuring this all out. The solar arrays and bi-directional meter have been giving their engineers fits as is.

I was just planning on biting the bullet and getting the Phase Perfect, as I was concerned about frying the electronics using RPC or VFDs. Plus I'm glazing over trying to understand this.

I was going to spend a bunch of time at IWF discussing power requirements with the Felder technicians. Hopefully I'll understand the detailed needs of the machines after that.

[Van Huskey]

OK. I'm involved with two parts of this thread.

1.) I get 0-60 in 2.8 seconds, and you almost pass out when flooring it. So I assume that with a larger battery in the P100D, you may actually pass out from the g-forces (not sure if that's a sensible upgrade). The ludicrous mode upgrade uses a rare-earth metal bus to handle the higher currents required for the ludicrous, not just insane acceleration.

2.) The planer and the thicknesser both have digital electronics, so I've got power concerns with them also. I'm planning on getting a Phase Perfect unit.

I was just planning on biting the bullet and getting the Phase Perfect, as I was concerned about frying the electronics using RPC or VFDs. Plus I'm glazing over trying to understand this.

I was going to spend a bunch of time at IWF discussing power requirements with the Felder technicians. Hopefully I'll understand the detailed needs of the machines after that.

1. I have one of the 2 or 3 quickest 0-60 production AWD cars with an IC engine and a Tesla in ludicrous mode can stay within a fender of me up to about 70. Their torque from 0 is incredible.

2. While I haven't directly confronted the issue personally the conclusion I have come to is I would personally use a PP if I had machines that had expensive electronics in them. No jury rigging just plug and play and sleep easy not worrying about if I am going to let the smoke out of a circuit board. I may be overly cautious but the money seems well spent.

[Matt Mattingley]

OK. I'm involved with two parts of this thread.

1.) Van is right regarding the two separate motor sizes on the Tesla Model S cars with the D designation (for instance, mine is a P85D, with dual motors (and 690hp), and the ludicrous mode upgrade with a smaller motor in front, and a larger motor in the rear. I get 0-60 in 2.8 seconds, and you almost pass out when flooring it. So I assume that with a larger battery in the P100D, you may actually pass out from the g-forces (not sure if that's a sensible upgrade). The ludicrous mode upgrade uses a rare-earth metal bus to handle the higher currents required for the ludicrous, not just insane acceleration.

2.) I've got a Felder A941 Planer with a 3-Phase 5kW (6.7 hp) motor, a D951 Thicknesser with a 3-Phase 4kW (5.4hp) motor, and an FB710 Bandsaw with a 3-Phase 5.5kW (7.4 hp) motor on order, that will be delivered in September. The planer and the thicknesser both have digital electronics, so I've got power concerns with them also. I'm planning on getting a Phase Perfect unit. I have a large solar array, and am tempted to have the power company bring 3-phase power to the workshop, but the engineers will have a heart attack figuring this all out. The solar arrays and bi-directional meter have been giving their engineers fits as is.

I was just planning on biting the bullet and getting the Phase Perfect, as I was concerned about frying the electronics using RPC or VFDs. Plus I'm glazing over trying to understand this.

I was going to spend a bunch of time at IWF discussing power requirements with the Felder technicians. Hopefully I'll understand the detailed needs of the machines after that.
Are you using two metres for draw/feed on your systems and what size generation system do you have? Do you have Power (battery or other) storage on property? What are your max kilowatt generation during peak hours? Are you 10 kW 100 kW or 1000 kW generation??? I’ve got a farm just down the road for me that’s wind/solar 1000 kW still under the two-year cycle. They are 95% feeding the grid.

Besides a few machines, are you in requirement/needs of three phase? Is your generation three phase through turbine generation??? I know you mentioned you have solar array...But what are your converter’s doing??? Three-phase or single phase? And where is this conversion primarily going to with your array?

[Alan Lightstone]

Are you using two metres for draw/feed on your systems and what size generation system do you have? Do you have Power (battery or other) storage on property? What are your max kilowatt generation during peak hours? Are you 10 kW 100 kW or 1000 kW generation??? I’ve got a farm just down the road for me that’s wind/solar 1000 kW still under the two-year cycle. They are 95% feeding the grid.

Besides a few machines, are you in requirement/needs of three phase? Is your generation three phase through turbine generation??? I know you mentioned you have solar array...But what are your converter’s doing??? Three-phase or single phase? And where is this conversion primarily going to with your array?

Wow. So many questions, and a few I can’t answer yet.

Right now there is one meter (single phase, typical residential meter). This will change, hopefully in a month, to a bi-directional meter for the solar to go back to the grid.

The solar array is about 39kW, so big for a residential system, but not insanely large. The converters on the array supply the house, and then the excess goes to the grid. Not sure how this would work if I got 3-phase to the house. I was thinking I’ll just add the phase perfect, and stay with single phase going into the house. In many ways that simplifies things, plus the power company will charge an arm and a leg to get 3-phase to the house, and I’m concerned that the monthly surcharge will be high. Actual usage would be low, as the machines wouldn’t be using power that much.

The only 3-phase need I will have is for the woodworking equipment. My 5HP Oneida cyclone is single phase. Same thing for the air compressor. So just 3-phase for the Felder equipment, which I will use one machine at a time, as I am a one-man hobby shop.

[brent stanley]

Wow. So many questions, and a few I can’t answer yet.

Right now there is one meter (single phase, typical residential meter). This will change, hopefully in a month, to a bi-directional meter for the solar to go back to the grid.

The solar array is about 39kW, so big for a residential system, but not insanely large. The converters on the array supply the house, and then the excess goes to the grid. Not sure how this would work if I got 3-phase to the house. I was thinking I’ll just add the phase perfect, and stay with single phase going into the house. In many ways that simplifies things, plus the power company will charge and arm and a leg to get 3-phase to the house, and I’m concerned that the monthly surcharge will be high. Actual usage would be low, as the machines wouldn’t be using power that much.

The only 3-phase need I will have is for the woodworking equipment. My 5HP Oneida cyclone is single phase. Same thing for the air compressor. So just 3-phase for the Felder equipment, which I will use one machine at a time, as I am a one-man hobby shop.

Hi Alan, talk with Phase Perfect. Some of their systems are used in grid tied systems to facilitate feeding home owner generated power to the grid. I believe there's information on their web site about this.

B

[Carl Beckett]

I ran a widebelt off a STATIC phase converter for several years. The main motor was 12hp I believe.

I paid $150 for the static phase converter (and am reselling it for the same now that I dont need it)

This limits hp, but for me it was never an issue and I never ran the widebelt anything close to full rating. I always thought I would pick up a used 3 phase motor to run with it as an idler and have a full RPC, but never did - because it never needed it.

Not for the purists. But it did work with zero issues for the particular sander I used it with.

[Bill Dufour]

https://www.wired.com/story/engineering-of-the-vw-pikes-peak-battery/
They must have some big VFDs on that car. But battery was dead after only 12 miles.
Bill D.

[Larry Edgerton]

I will read this again when I have a clear head, been in the truck for 28 hrs picking up that Wadkin profile grinder. As you know Jack it has two motors, .18hp on the pump, and a 1hp on the grinder. I have 3 phase but not where I want the grinder. I think I want the grinder in the basement of the house away from all the dusty bits. Maybe not, what do I know, never used one before?

Read the manual, tired and confused. Talk after sleep.

[Bill Dufour]

at 0.18 hp I would replace the pump with 1/8hp pond pump and use a vfd to supply the main motor. A vfd will have a switched relay that can control a power relay for the pump. You can even use a 120 volt input VFD for up to one hp loads.
Bill D.

[Matt Mattingley]

Most single phase VFD‘s can handle a in rush of 150%. Most motors have a in rush 6 to 10 times Motor nameplate amps(under hard start or knife switch) If a Vfd is sized properly can handle a fractional horsepower start load without a hick-up. Proper time delay fusing is still required for the smaller fraction motor. The VFD will like it better if both motors were started together.

For example;

-if you wanted to start the pump motor at the same time as the main motor a 2 hp VFD would suffice but, fusing for the smaller motor is required.

- if you wanted to hard start the smaller fractional motor while the main motor is running.... you take the FLA of the smaller motor, multiply it by 10, then multiply it by .66 Then add this to the total surge FLA (at the minimal). Example; 1 hp 3 p = 4ish amps at 220v + 0.2 hp 3p x 10= 2a ... 4 A +2 A equals 6 A this would equal the next VFD size larger would be a 3 hp VFD.



Vfd’s don’t like to be knife switched for full load hz. But under fractional horsepower, add on’s (when the vfd is size properly and fused for the fractional horsepower) it is with in its scope.

A 50 hp VFD can pretty much start a 5 hp motor( or less), under hard start knife switch any day the week. But if this is what you’re looking for just go buy a phase perfect. Or 10 horse power “North American Rotary phase converter” or American rotary also sells good units. I just don’t like how they have the ability to single phase.

Is anybody here using “American rotary” that do not like the single phasing? I actually consider it dangerous.

These are what I call the opinions of the author.

[Doug Landphair]

John, this may (or may not) be of some help to you. I just purchased a used Grizzly G0514X3 bandsaw equipped with a 3-phase motor. Normally, I wouldn't even consider a 3-phase but the previous owner had equipped it with a WEG VFD. I'd never heard of such a thing but it works great. This is not exactly a plug-and-play piece of equipment. Aside from needing to make the proper connections, this VFD is programmable. It turns the motor into a soft start motor. You can program the time needed to bring the motor up to speed. In my case, it takes about 5 seconds or so to come up to 100% power. The VFD is also programmed to do a soft power down. Once I hit the off switch it takes about 5 seconds to power down. I can also use the foot brake to bring it to a faster stop, if necessary. I researched the replacement cost for these VFDs and it looks like a new one would cost about $300 or so. They make various VFDs with various capacities and you would probably want to talk to their customer service people to get the correct one. This seems to be geared to industrial applications but sure works well for me in my little shop. Here's a pic or 2:

390774390775

[Van Huskey]

John, this may (or may not) be of some help to you. I just purchased a used Grizzly G0514X3 bandsaw equipped with a 3-phase motor.

I think John's issue is the machine he is interested in powering has electronic controls. Something like the 514 is a simple use of a VFD since you are just powering the motor, the question is how to approach powering a machine that has potentially "delicate" electronics in the chain.

BTW have you made any headway on wiring the brake microswitch into the VFD?

[Carl Beckett]

This seems like a lot of work to get a VFD to work.

The rotary phase converter I purchased was 10hp rating, and cost (used) $500 off CL

[Alan Lightstone]

Did you call up Felder and ask for advice?

[Rod Sheridan]

That’s what I thought you’re thinking might be. The only for seeable problem I can see Is the VFD will not have any stop command for breaking.

That's true however the J/P doesn't have braking from the factory.............Rod.

[Matt Mattingley]

Did you call up Felder and ask for advice?
Felder does not like giving workarounds for their wiring schematics. Nor do any companies. This is where companies like phase perfect, North American phase converters , American rotary phase converters or VFD’s come into place. Nobody can absolutely advise you on your best situation. This is what formus are for....

[Bill Dufour]

On my no name. China VFD Huanyang clone the braking circuit is not NC it is NO I consider this less safe since a bad switch will not stop the machine. It also means more wires since the switches are not in series. I could not figure a way to latch the stop circuit off either.
That said I have a e stop button on the headstock which is what I mostly use. It mechanically lathes off and must be rotated to turn it back on. The foot brake stops it both electrically and with. brake shoe. But take your foot off and it restarts. On the apron I have a forward-stop-reverse switch which mechanistically latches into each position as well.
Bill D.

[jack forsberg]

On my no name. China VFD Huanyang clone the braking circuit is not NC it is NO I consider this less safe since a bad switch will not stop the machine. It also means more wires since the switches are not in series. I could not figure a way to latch the stop circuit off either.
That said I have a e stop button on the headstock which is what I mostly use. It mechanically lathes off and must be rotated to turn it back on. The foot brake stops it both electrically and with. brake shoe. But take your foot off and it restarts. On the apron I have a forward-stop-reverse switch which mechanistically latches into each position as well.
Bill D.On the ones I have made we have at least 10 terminal strips location that can activate any command including stop in NC or NO And because they are separate temanals they have their own breaking command when signaled . For instance your foot break would be programmed with the coast to stop so that the foot break could be applied Without throwing a fault.but it for instance could also be set as soon as you left off your foot on the break it’s signals for DC injection breaks to bring the machine to a complete stop . Ours require and none of the traditional ways of wiring switch controls and it does not matter whether they are normally open or normally closed momentary or maintain.

[Doug Landphair]

Hey, Van. You certainly would know more than I about whether a VFD like the one that came with my 514 would work for John or not. My thought was that it may be something that might work for him. VFDs are definitely not in my area of expertise!

No, I haven't made any progress on the microswitch. Haven't had time yet to talk to a buddy of mine who would know about those kinds of connections.

Best,

Doug

[Mike Heidrick]

The external dc braking i put on my wj200 for my big cnc mill works under any stop situation. I stop it under gcode fpr example. You wire in the brake and program to enable the external brake and set the time to decelerate. You would wire your estops to activate stop is all. Estops can be any form of switch, the intelligent inputs can be wired for most any type.

[Bruce Eaton]

Hi John. Did you end up buying the machine? I have an AD751 that I have yet to power up. Don’t need it in the shop I’m in and we don’t have an outlet that will fit the 5-prong plug. I’m preparing a shop at home and was thinking of using VFD’s or a rotary converter. I believe my tool is 5.5 kw. There might be name plate info for the bed motor as well. I also have a three phase 5hp tablesaw, 3hp bandsaw 3hp dust collector and a 1-2hp Felder horizontal mortiser so maybe the rotary phase converter would make more sense than multiple vfds. I was also wondering about wiring and panels necessary for each type of setup.

[Albert Lee]

I have a Felder AD951 and I have a VFD on my 18.5kw SCM sander. (has 2 motors)

I think I am in position to share my thought on this topic

The variable speed control on the AD951 is a single phase inverter, it is activated by the neutral wire/signal, I think for AD741 there is a 2 speed function. is it a single phase or 3 phase motor doing this, I am not sure, but given my experience and lesson learnt from my SCM sander and VFD application, your electrician will have to by pass the power so the VFD is controlling the main motor of the sander. the second motor on the sander controls the feed of the mat.

[David Atterbury]

Did this ever get resolved. There are a couple of these threads in history but they end without a conclusion. Did you end up getting a VFD?

I am in the process of buying a FELDER AD741 3 phase and plan to install one of Jack Forsberg’s VFDs on the motor side and run single phase 230v to the power drive electronics. Has anyone done this and would care to share their experience?

[Rod Sheridan]

Did this ever get resolved. There are a couple of these threads in history but they end without a conclusion. Did you end up getting a VFD?

I am in the process of buying a FELDER AD741 3 phase and plan to install one of Jack Forsberg’s VFDs on the motor side and run single phase 230v to the power drive electronics. Has anyone done this and would care to share their experience?

I have done that on a CF741.

It takes a bit of work, however it can be done. It cost about $1K for parts and $300 for inspection.....Rod

[Brian Runau]

John:

The motor has to be wired to take the change in speed. If it is not wired for it, and you turn the speed down to slow for the turndown ratio on the motor you will burn it up. Brian