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Choosing VFD For Deckel FP2

Degull

Aluminum
Joined
Feb 3, 2014
Location
Toronto Canada
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Hi everyone. I plan on installing a VFD on my newly acquired FP2. I have 1 phase 230V available (Canada). I am not sure where to start. I have attached a picture of the motor name plate. It looks like a 550V 3HP motor. Do I need a VFD that will output 550V?
 
I plan on installing a VFD on my newly acquired FP2. I have 1 phase 230V available (Canada). I am not sure where to start. I have attached a picture of the motor name plate. It looks like a 550V 3HP motor. Do I need a VFD that will output 550V?

Typically a VFD will output the same voltage (or less) than the input. So for example a 3-phase 230V motor can be powered from a VFD which in turn is powered from a 230V single phase line.

In your case you will need a transformer to step up your 230V single phase to 550 or 575V single phase, then a VFD which can convert that single phase to three phase at 550 or 575. Unfortunately all the 575V VFDs that I know require three phase power as input.

One other possibility: your motor may have the option to run it wired either delta or star (internally). The higher voltage configuration would then be star (or Y or Wye) at 550V and the lower voltage delta configuration would be run from 550/sqrt(3) = 317 volts. Unfortunately I can't read the nameplate in your photo to see if it can be wired in either configuration. If it can be wired delta at 317 volts then you could also get a 230V to 380V transformer (very common) and run this from a 380 or 400 volt VFD IF you can find a 380 or 400V VFD with a single-phase input. But again, I don't know of any.

Most economical might be to get the motor rewound at a motor shop to run from 230V 3-phase. Or replacing the motor with a 230V 3-phase one. Then you can use a VFD like this: https://dealerselectric.com/L510-201-H1-U-OPENBOX.asp

I suggest you contact Dealers Electric (link above). I have purchased 3 VFDs from them. They have low prices and fast service and have been very helpful. Email them a photo of the nameplate then give them a call.

PS: there is a forum on PM exactly for these kinds of questions:
https://www.practicalmachinist.com/vb/transformers-phase-converters-and-vfd/
 
When I ran into this problem on an Aciera F4, I changed the motors to 3-phase, 240-V and added two Hitachi WJ200 VFDs to run them. When I ran into this problem on my Aciera F5, I bought two 240V-575V single phase transformers and wired them in an open delta configuration to make 3-phase 575-V power from 3-phase 240-V coming from my RPC, which I later swapped for a PhasePerfect. Either way works just fine, but the Aciera F4 re-motoring was a lot more work.
 
Typically a VFD will output the same voltage (or less) than the input. So for example a 3-phase 230V motor can be powered from a VFD which in turn is powered from a 230V single phase line.

In your case you will need a transformer to step up your 230V single phase to 550 or 575V single phase, then a VFD which can convert that single phase to three phase at 550 or 575. Unfortunately all the 575V VFDs that I know require three phase power as input.

One other possibility: your motor may have the option to run it wired either delta or star (internally). The higher voltage configuration would then be star (or Y or Wye) at 550V and the lower voltage delta configuration would be run from 550/sqrt(3) = 317 volts. Unfortunately I can't read the nameplate in your photo to see if it can be wired in either configuration. If it can be wired delta at 317 volts then you could also get a 230V to 380V transformer (very common) and run this from a 380 or 400 volt VFD IF you can find a 380 or 400V VFD with a single-phase input. But again, I don't know of any.

Most economical might be to get the motor rewound at a motor shop to run from 230V 3-phase. Or replacing the motor with a 230V 3-phase one. Then you can use a VFD like this: https://dealerselectric.com/L510-201-H1-U-OPENBOX.asp

I suggest you contact Dealers Electric (link above). I have purchased 3 VFDs from them. They have low prices and fast service and have been very helpful. Email them a photo of the nameplate then give them a call.

PS: there is a forum on PM exactly for these kinds of questions:
https://www.practicalmachinist.com/vb/transformers-phase-converters-and-vfd/

Thank so much for your help, you have helped me so many times, I can't say thanks enough.
I would prefer to have my motor rewound (cheaper), but do you think it would be better to bite the bullet and buy a new 3 phase 230V motor?
 
In UK at least, motor rewinds for 3hp motors are typically 'not economically viable', meaning that it is cheaper to just buy a new motor. Rewinds are still economically viable where you have a special motor and you can't just get a new one off the shelf. I expect your FP2 motor to be a standard frame size (but not a typical US frame) so that doesn't apply.
 
Do you want a VFD for the capabilities it offers? Or do you just want the mill up and running?

If the latter I'd consider buying a suitable single phase motor made for the local power supply. Maybe an adapter plate for mounting it might be required. That is stuff you can check out when the motor is removed. I think the removal of the motor is required no matter which way you choose to go.
 
Are you running your FP2 from Deckel's electrical box that was supplied from the machine? Has a few advantages, such as an interlock to prevent a guy from starting the spindle when the microscope is in the quil. If you don't have the electrical box, then just re- motor your mill with 220volt, preferably 3phase.

Nice mill. I have it's sister from just down the road from you.

Lucky7

(On the off chance you want the 575volt electrical box, I'd sell mine)
 
As mentioned above, the motor is coming out anyway, find a good motor shop and bring it to them. You have lots of options, large HP single phase, rewire the motor (the price might be reasonable), etc. They will also check out the motor's condition, BEFORE you spend any money on it. When I brought the last three phase motor to the shop the guy said one phase was just about to burn out. I was lucky with my FP1, it has a one HP DC motor on it with a variable DC drive, another option for you to consider. The variable speed is a great feature and has spoiled me. Not sure where you are, but the shop I'm talking about is in Alliston, Ont. Bryan's Electric Motors And Pumps; they are in farm country and are very helpful with this kind of stuff.
 
Getting the motor rewound is going to cost the same as buying a new motor. I spoke to dealers electric today and they have this motor that will work:
Brook Crompton BA4M004-4C 4 HP TEFC Factory New Motor at Dealers Industrial
I think going with the VFD and a 230V 3 phase motor makes the most sense. I don’t think I’ll ever use the electrical cabinet that came with the machine. I want to have the ability to run in reverse and use a brake resister.

AF5143B2-64A6-4F22-9D29-7E97DC486AE7.jpg
C300EE2D-2630-4CD8-9453-A01B6CA69A96.jpg
1EED94DD-9C4C-462A-98EB-EC590E4475D7.jpg

I managed to get the machine back on the ground today.
 
I had the same issue on my Maho MH 600. It has a main motor (real easy to change) and a feed motor buried inside (harder to change). I already had 3 phase 240 from a rotary converter for the other machines. I got a used 240-600 3 phase transformer for $100. It works great (4 years and zero issues). It opened up opportunity for a couple more 575V machines. I know a couple other folks who have gone the same way to get 575V 3 phase.

What option to choose? I guess it depends on what your situation is.
 
Thank so much for your help, you have helped me so many times, I can't say thanks enough.

I'm happy to help. It's fair, because I've also gotten lots of help from others here.

I would prefer to have my motor rewound (cheaper), but do you think it would be better to bite the bullet and buy a new 3 phase 230V motor?

Most large cities have at least one motor shop where a rewind would cost less than a brand new motor. These are the kinds of places with a handful of old-timers who have seen it all and done it all. Stacked in every bit of free space are also motors for sale. These typically have been cleaned, gotten the bearings swapped, and rewound/repotted as needed. Sometimes also balanced and/or repainted.

Ask around to find the right place. If you just take your motor there and explain your situation, they will look it over, evaluate the options, and can probably offer you a cost-effective solution, or at least advise you what to do.

(I don't know if the motor is a standard European frame/shaft/mounting size. If so, a brand new 3-phase 3HP replacement one can be had for $200-$300. Used is less. A new VFD can be had for $120 (see link above). But if the frame/shaft/mount are non-standard, it gets harder to judge. Hence my advice to take it to a good motor shop.)

[EDIT]
I missed your post from 6 or 7 hours ago. Nice looking machine!! If the motor Dealers Electric have offered is a drop-in replacement then that seems like a good way to go. I agree that 3-phase + VFD is a good solution, that's what I would do. But I don't see a suitable VFD (230V single phase in, 4HP) on their web page. Did they suggest a 3HP VFD?

Also, if you reverse the motor the machine will still run, but the feeds won't work because the clutches and dogs are designed for only one direction of rotation. Probably OK for backing out taps, but I have not done this myself.

If what you need is a C-face 100L frame 1800 rpm 3HP (2.2kW) VFD-compatible motor, these cost less than 200 Euros new in Germany. Drehstrom-Motor IE2 Energiesparmotor 2,2 kW 1500 U/min. B5, Elektromotor | eBay
If you click on the last picture then you can compare the mounting dimensions and shaft size to what you need. This plus a 120 USD VFD from Dealers Electric would get you going at pretty low cost, if you can find a Canadian source for the motors to avoid shipping costs.
 
Rewinding a motor in Germany and other places must be cheaper than a new motor, or 2nd hand is rare. But in Finland a rewind would only ever pay if the motor was special and could not be replicated. Any 3phase motor rewind I doubt would go under 400 euros but probably more from what I've been told by people who have had it done.

And second hand motors are very plentiful here, I have a collection of 4 - 5 3ph motors (spares, future projects) between .5 to 4 kW and the average purchase price was 25 euros.
 
Conditions will vary ...very local so you need to do your research.
Bought an FP3 years back. Came from an aircraft works (Northrup) and they had rewound the motor for 440v 3 ph ....
Wished to upgrade the machine to increase its spindle speed range to mimic the later versions. (25-2500 RPM)

Local electric motor shop (did work for Mare Island Navel ship yard) rewound the motor for 220 v,3ph dual speed....
Bit different here as the motor has integral electric brake so replacement would have been difficult.
Think i paid $350.00 for the job, to include new bearings, potting and balance......

On another note, i am familiar with the need to use the on /off function of the VFD and that its not recommended to switch the down stream output of the VFD.../
But wondering why its not possible or OK to step up the output of the VFD......A transformer really doesn't interrupt the output... Why isn't it Ok to just step up the 220 output to feed the 550v motor?
I do this all the time with my Phase Perfect...works great.

Cheers Ross
 
But wondering why its not possible or OK to step up the output of the VFD......A transformer really doesn't interrupt the output... Why isn't it Ok to just step up the 220 output to feed the 550v motor?
Cheers Ross

That is a good question to which I would also like an answer.

My guess is that it would work OK with a modern VFD, but there would probably be a problem with running in sensorless vector mode. This usually involves the VFD 'exploring' the electrical and magnetic characteristics of the motor while it runs it in a test pattern. I suspect that the automatic motor tuning would not work well through a transformer. Of course you may only need to run in V/f mode so the problem (if any) might be avoided that way.

Hoping a VFD guru can comment on this
 
Hi Ross,

But wondering why its not possible or OK to step up the output of the VFD......A transformer really doesn't interrupt the output... Why isn't it Ok to just step up the 220 output to feed the 550v motor?

That's a good question. In other words take a 230V single phase power source, feed a 230V VFD which generates 3-phase 230V output. Now feed that 230V 3-phase output to a 3-phase step up transformer, which transforms it to 3-phase at 550V. Now feed the 550V 3-phase motor.

This is unconventional but from what I understand it should work OK. When programming the VFD with motor parameters, one must take care to multiply all motor voltages by the ratio 230/550 when entering the values into the VFD, and all motor currents by the ratio 550/230. In other words if the motor rating on the nameplate is 550V/4A this should be entered into the VFD as 230V/9.6A, because the transformer will convert that to 550V/4A.

If a suitable 3-phase transformer is at hand, that would be a simple solution. BUT note that the transformer will only work correctly at the design frequency (nominally 60 Hz in North America). So you would lose the ability to change output frequency and motor speed: the VFD would have to be left at 60 Hz.

Cheers, Bruce
 
If a suitable 3-phase transformer is at hand, that would be a simple solution. BUT note that the transformer will only work correctly at the design frequency (nominally 60 Hz in North America). So you would lose the ability to change output frequency and motor speed: the VFD would have to be left at 60 Hz.

Really? Somehow, I can't believe that.

We're talking about a pairs of coils right? Inductance right? Nobody told the coils to work only at a specific frequency, they don't know about that. They just conduct alternating currents that create a varying magnetic field that induces another current in the other coil.

So, it's 3 phase, maybe your transformer has 3 pairs of coils, I never thought about that. But for sure, no coil cares about the frequency.

Jacques
 
We're talking about a pairs of coils right?

No. In addition to the coils, there are also the metal plates inside the transformer, and those are the issue, because they will saturate. As you lower the frequency of operation, these plates need to saturate at a higher magnetic flux in order to maintain the transformer's performance. Then there are a set of issues related to hysteresis, eddy current losses, and so on.

This is why high-frequency transformers are physically smaller than low-frequency transformers.

Bottom line: typical voltage-conversion power transformers have a narrow range of frequencies in which they operate properly.
 
Really? Somehow, I can't believe that.
We're talking about a pairs of coils right? Inductance right? Nobody told the coils to work only at a specific frequency, they don't know about that. They just conduct alternating currents that create a varying magnetic field that induces another current in the other coil.
Jacques

I believe ballen is quite correct, although you should get away with very small variations in Hz. I again guess that reducing the frequency output from the VFD will cause more problems for the transformer than increasing the frequency, but I feel I am on fairly thin ice. Certainly there is a construction difference between 50Hz and 60Hz power transformers at the same rated outputs. Power transformers are fairly highly optimised so they will deliver their stated output (just) at the rated frequency. The amount of copper and iron is carefully optimised to just meet this requirement but not outside the design frequency.

Again this is an issue that really needs a VFD and power electronics guru to give a definitive answer and more important, actual experience in operation.
 
Will work if a VFD in V/F mode is run up to line frequency, 50 or 60 Hz as appropriate before the motor is turned on. Basically you are just using the VFD as a power oscillator to drive the transformers. Nothing novel about that except for the VFD giving you all the drive control and power electronics in an inexpensive package.

VFD needs to be suitably oversized so that the motor start surge will be below the short term overload limits. If the motor starts off load you can probably set a dynamic current limit rather lower than the normal start start draw. It will run up bit slower but that out to be fine unless taken to extremes. I imagine the transformer inductance will help smooth things too.

Never actually done this myself but I do know of application notes produced in early VFD days when the necessary building blocks for basic VFDs became available in integrated circuit form claiming that this sort of thing was possible and practical. Indeed I'd be unsurprised to discover that the whole VFD thing grew out of solid state voltage and frequency increasing drivers for, probably, military purposes. Looked into doing this myself using a variant of the design published in Elektor at the tag end of 1994 to avoid digging into a special motor to find the star point but it was way too expensive.

Sensorless vector mode will almost certainly not work with the transformer in the way.

Clive
 








 
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