VFD – which is best please ?

[Pete.Participant @pete-2]

Hi Robert Atkinson,

You may not have wanted to comment on this thread, but I'm glad you did, as someone who has very limited electronic knowledge I do like reading comments from someone who clearly has a professional attitude to electrical safety, what people wish to do in the privacy of their own workshop is one thing, promoting it publicly is another.

I don't know how items that come in from China in shipping containers before being sold on ebay go through any genuine safety checks, but if people are relying on this happening in China before making their way to fly by night traders on ebay, well they have optimism I certainly don't.

[SteviegtrParticipant @steviegtr]

Hi guys & gals . So to do a recap on all the ops answers of which VFD should i buy.

Most of the answers were pertinent to the the question. But some were from spurious members that just want to belittle other members. Namely Robert. I see that Robert seems to give mostly negative comments to other forum members. This is rather sad, as this forum is occupied by genuine folk who joined this forum for information on a particular point they need help with. I tried to do just that. Mainly i had very good comments & particularly from the person asking the question. Albeit via a private message. The main question in this what maybe a wonderful new year is, why do the very few members seem to disparage others. I know not the answer. I seem to think it is something to do with envy, or i wish i had what you have. Not sure , but of any members that think that way should stop in this year of out Lord 2022. Be kind to others & friendly. It costs nothing & reaps many benefits.

A very Happy new year to all the model engineering forum members & keep up the good work.

Steve.

[David JuppParticipant @davidjupp51506]

Emgee,

 

"I believe the reason for calling the VFD a component is because the units can be supplied without a keypad, this is common for commercial and industrial users, so cannot function without another part or means of control."

No – it's because the VFD is for incorporation into a 'machine' or system (see declaration below). Because the VFD on it's own can't actually 'do' anything useful, it has to be combined with other things (e.g. a motor). Lenze can't control that step (apart from some of the warnings that I didn't copy from the manual).

 

"If the unit is likely to cause EMC interference in residential areas it will surely do the same in an Industrial installation, I am surprised that Lenze appear to have opted out of any responsibility."

Lenze can't control how well or badly the VFD is installed, nor what it is connected to – cable type & length, glanding, enclosure type, earth bonding, all make a difference. It's up to the designer/installer to get that bit right, and perhaps actually test the completed system. That might depend a lot on where it will be operated.

Domestic equipment could end up anywhere, alongside all kinds of sensitive kit – so the EMC requirements have to assume a reasonable worst case.  So for domestic use additional filtering might be needed (as an example). 

Some VFDs include internal input filters, some don't (assuming the installer will add one that suits the application).  In one project I did using a small i510 the added 'medical' input filter was almost as large as the VFD itself.

 

From the Declaration of Conformity for the same product

• According to the EMC directive, the listed devices are not independently operable products. Compliance of the directive requires the correct installation of the product, the observance of specific installation notes and product documentation. This was tested on specific system configurations.

 

• These products are intended for installation in machines. Operation is prohibited until it has been determined that the machines in which these products are to be installed, conforms to the above mentioned EU Directive.

Edited By David Jupp on 01/01/2022 09:41:48

Edited By David Jupp on 01/01/2022 09:44:24

[SillyOldDufferModerator @sillyoldduffer]

Posted by Steviegtr on 01/01/2022 02:12:14:

…

Most of the answers were pertinent to the the question. But some were from spurious members that just want to belittle other members. …

…

Be kind to others & friendly. It costs nothing & reaps many benefits.

A very Happy new year to all the model engineering forum members & keep up the good work.

Steve.

Steve, please avoid personal attacks. Accusing people by name is a step too far.

I don't think the other party is picking on you. In this thread you posted a link to a video aimed at beginners. It contains a few examples of dubious electrical practice which in my opinion shouldn't be visible in an educational piece, especially when the commentary mentions you were an electrician. The video suggests that the electrical arrangement is good practice, and it's not. Don't be surprised if these things get noticed – it's on the Internet!

I welcome having my mistakes pointed out. Corrections help me and everyone else. I never take it personally.

I think the point has been made on both sides. Let''s move on.

Dave

 

Edited By SillyOldDuffer on 01/01/2022 10:13:18

[Martin of WickParticipant @martinofwick]

For the benefit of the OP, good advice at the beginning of the thread.

If not familiar with this class of device, almost any branded product from a reputable UK supplier will be suitable (several have been mentioned). You will have peace of mind, a guarantee of some sort and useful back up. one of the vendors supplies helpful quick set up diagrams if you go down the DIY route.

Avoid web sourced unbranded generic VFDs unless know what you are doing, content with the associated risks of inadequate documentation, zero back up, worthless guarantees and quality control issues. etc. Many (including myself) have managed to get useful service from these units but that has come (in my case) at the cost of a great deal of time and effort trying to understand and test the available control parameters etc.

Assuming you purchase from a UK supplier…

You will pay more (much more in some cases) for a full installation solution/package of motor pendant VFD all wired up, but it will save you time and may be a lower risk solution.

You do not need a complex VFD device with hundreds of weird and wonderful parameters that you are unlikely to use and that has a premium prices accordingly. A simpler unit will be perfectly adequate for a manual lathe drive, just check that the control functionality suits your requirements (ie do you need braking, ramp start, reverse, jogging, e-stop, reset etc). I assume that your lathe is not set up as a CNC device, in which case you may need additional control functions.

A vectored thrust device to give more low speed torque is desirable but you are likely to have to pay more than for a simpler device.

The VFD power rating should match the rating of the intended motor. A slightly higher rated VFD will be OK, but not a unit that is rated at less than the nominal motor power rating.

Ultimately I would ask do you really, really need a VFD? If the answer is because you want to use a 3 phase motor and benefit from the smooth and quiet power delivery and low voltage controls, then pass GO and expend £200 in blood and treasure.

If the answer is 'because I cant be arsed to change belt position every time I switch from turning to threading' then you might well be disappointed with the outcome.

 

Edited By Martin of Wick on 01/01/2022 12:15:45

[VicParticipant @vic]

I’m not sure if I’m allowed to post this link but a Mod can always remove it if required.

These folks seem to have some competitively priced packages with 3 year warranty.

**LINK**

[Robert Atkinson 2Participant @robertatkinson2]

I will not be posting pictures of my workshop as it is far from pristine and I would not want people to think what I do in my personal workshop is an examples of good practice. I have enough training and experience to assess the risk to me and put appropriate mitigation in place. My acceptable risk to myself is higher than I would expose others to either directly or by giving advice.
I will post pictures of my ML2 and it's new drive system when i get round to doing some more work on it. I've never been a "crop duster" but have designed and built systems, including motorised flight controls, for a British turboprop agricultural aircraft.

Happy new year and stay safe,

Robert G8RPI.

[Neil WyattModerator @neilwyatt]

To reinforce what Dave has said, please can everyone avoid personal attacks.

There is an 'ignore member' button available and I suggest using it rather than getting into scraps.

I don't want to have to start the New Year with locking threads.

Also, sometimes people make statements or share content that has elements some people may disagree with.

Yes, it is reasonable to point out things like missing earths or cables draped across machines etc. but equally we need to be aware that most photos don't tell the whole story. We also should avoid turning comment on one or two issues into a checklist of minor niggles.

Neil

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[Tim StevensParticipant @timstevens64731]

The question asked for 'any advice as to most reliable make'.

This can only be answered by someone who has put a all available makes of VFD through a test process and recorded the results. Also, any test of reliability is certain to take a long time. Together, these factors make it unlikely that anyone reading this could answer the question.

Is reliability the only criterion? It is certainly a factor, but how about ease of setting up? Or availability of spares? Or someone to help sort you out when you get stuck? Or efficiency – power in compared with power out? The most reliable kit in the world is no use if you cannot read the instructions.

Help us with these questions, and we might be able to help further.

Hoping this helps – cheers, Tim

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[EmgeeParticipant @emgee]

Tim

There were 2 statements of reliability within 30 minutes, l for over 6 years use without any problems in the post by John Fletcher.

But your statement ref a test process and recording results is absolutely correct IMO.

I wonder if BR went for the vector control and a TEFC Inverter rated motor or the Myford conversion that uses an vented endcap and casing motor, if the latter then it would be advisable to make some shielding spaced off the motor casing to prevent any chips or splashed cutting fluid getting forced onto the motor windings.
Both are available from the same source.

Emgee

[Mike PooleParticipant @mikepoole82104]

Reliability is designed into a product in the first place and then strict process control and choosing quality high spec components for manufacture should result in a reliable component. The installation of the component will have a part to play in the life of the device. A car factory body shop is a pretty hostile environment and control panels with damaged doors or seals collected a lot of filth that covered everything. The panels should be dust and liquid proof and temperature controlled heat exchangers kept the filth outside as long as the doors were kept closed and in good order. I could have a good night out if I had a pound for every mysterious robot fault I was called on that turned out to be cooling fan failure, eventually the message did get through and fans and filters were part of planned maintenance given special attention as summer approached. The home workshop is unlikely to stress a VFD to anything like industrial levels but time is a factor in capacitor life that cannot be controlled. Manufacturers of quality VFDs would probably expect a life of up to 12 years but anything over 5-7 as good going. I have an Hitachi J100 that is around 23 years old and was an early arrival of flux vector technology, the flux vector feature is a selectable mode and makes a huge difference to low speed performance. It only takes one chip of swarf to kill a VFD if it finds its way inside the drive. My Dewalt fast battery charger was an open design that would pass anything other than a finger, one chip of aluminium found its way in and that was the end of that. When I look round my workshop I find swarf in every corner, an interrupted cut at high speed on aluminium will send small chips surprisingly far. I was a sparky in a tool room for three years and swarf and cast iron dust found it’s way absolutely everywhere. European, Japanese and American brands are generally pretty reliable and likely to have a long life in a home workshop but bear in mind that even with light use some components still age so eventually failure will occur. The difficult area is the bargain basement end of the market, the low price is achieved by cutting corners somewhere or perhaps everywhere. Poor design can lead to an unsafe or unreliable drive, the basic feature set may not be an issue as running a lathe is a fairly basic task for a VFD. Not attending to EMC issues can feel like a victimless crime as you may well not cause anybody any problems, on the other hand you may be unaware that your neighbours are having equipment problems that they can’t pin down. It is perhaps unfortunate that a VFD can be installed with no more than two pieces of cable and you will have the machine running. In my opinion this falls well short of an acceptable installation but if you are fully aware of the shortfalls and are happy to proceed then it’s not my problem. People are taught to drive properly and safely but many choose not to.

Mike

[EmgeeParticipant @emgee]

Mike

How many low price VFD's have you inspected, tested and recorded the results as Tim suggests ?

There are low price VFD's being sold by reputable dealers, 1 offers a 3 year warranty on a motor + VFD package so must be fairly confident of the reliability.

Emgee

[Mike PooleParticipant @mikepoole82104]

Of course I have not gone though the exercise of testing VFD drives but I have seen plenty of cheap electronic equipment and quality is usually in short supply. The Jaguar Cub drives are guaranteed for 5 years so they must be sure of their reliability but they are a good quality drive. Cheap and high quality are pretty much mutually exclusive and is one of life's truisms. A cheap drive may well turn out to be value for money if it performs as hoped for and lasts for a reasonable time. If something is cheap enough then throwing it away when it fails will not be too painful. It will be interesting to see whether anyone posts about their 23 year old £50 drive in the future.

Mike

[SteviegtrParticipant @steviegtr]

When working I contracted to Blue chip companies. Usually the food industry. You all eat plenty of there products. The ones i fitted & were specified by those clients. Were Alan Bradley & Imo Jaguar. The largest i fitted was to a fondant cream plant pre mint injection. They were for pumping the cream in a famous mint later than 8 oclock. These were 22KW Filtered & backed up by A.B MMS.

They were always pretty reliable. I do remember one failing on a Saturday night & me chasing round to get a replacement. The cost from memory was in the region of £2300. In over 25 years in the food industry we probably replaced around 100 of these drives. These things were running 24 hrs a day on continental shift patterns with P.M's done once a week. The failed Imo jaguars were repaired & returned to stock.

They ranged from .55kw up to the said 22kw. Nearly all were 3phase in / out. On the odd occasion I fitted the small Cub inverters. On small plant that did not require high torque start. As many have seen on my video's i have used good quality branded inverters on my machines.

But to be honest i have friends with workshops running the Cheap imported inverters on both large Colchester & Harrison lathes. 2 of them have the same fitted to there milling machines. 1 a Beaver & the other a Bridgeport.

Both the ones with the milling machines are mounted up to the right of the mill unenclosed & operated with the keypad only. Both have had them for many years & do use them a lot. None of my friends inverters have ever failed so far. The only downside i can say is they are a bit dirty electrically.

On occasion they do run a little lumpy but perfectly usable on a hobby level. I don't think you will ever see a large company using the cheap Chinese VFD's but it's not to say they are no good.

As for the home hobbyist needing to buy filters for the input i would say no. Not required. As an example I have a Dab radio sat on a shelf directly above my inverter, which i always have switched on. Never bats an eyelid

However i do have a cheap led work light over the lathe & when i switch that on the radio goes lulu.

Apart from watching my neighbours wandering around their gardens with a tv aerial in there hand all is good.

Take note from a old dog rather than a Google ologist.

Steve.

[Anonymous]

Out of idle curiosity I googled "old dog", and it said you can't teach them new tricks.

Andrew

[Former MemberParticipant @formermember12892]

[This posting has been removed]

[EmgeeParticipant @emgee]

Mike

Pictured a Fuji VFD removed from a frozen food factory, it was surface mounted without further protection adjacent to and controlling a flat belt conveyor from a blast freezer carrying frozen potato chips through a metal detector and discoloured chips that removed the discoloured chips and of course any metal fragments, they were removed from the belt by a pneumatic arm.

The belt and detector were on a mezzanine floor so any removed bits fell into a chute to a waste bin, the product carried on and discharged into another chute that went to a Euro pallet size 1.5M high plastic bag lined wooden crate and then to the frozen product cold store to await packaging in another part of the site.

I don't know the date of manufacture but I removed it around 1995, last time I used it was to test run a motor after fitting new bearings about 3 years ago when it worked OK, you will see the test cables coming out of the gland plate, pity I didn't fit at least a grommet.

I believe this would have been purchased mid 1980's so now 35+years old, a top of the range and high cost VFD when purchased so it does give a thumbs up to reliability of the more expensive unit.

Emgee

Edit to remove a picture.

 

 

Edited By Emgee on 02/01/2022 13:12:29

[Mike PooleParticipant @mikepoole82104]

Emgee

That has done exceptionally well to still be alive after 35 years, it looks to be quite an effective standalone case but would not be sufficient in a car factory body shop, apart from the metallic particles of weld expulsions from spot welding a hoseing from failed water cooling or a weld tip being pulled off has to be protected against, ideally the pressure and flow monitoring should shut the water off but not always effective. Inverters were not at a stage where they were ready for large scale installation in our factory around 1980 and Demag micro speed units were widely used for applications where a VFD would be first choice now. By the mid nineties VFDs were in favour and when the MINI line was installed in 2000 the standard was SEW Eurodrive VFDs and motors which are very sophisticated drives. The German car industry has much influence on their suppliers and SEW now build a complete module to control a main hoist motor with absolute encoder positioning and all the other motors for centralisers and track locks etc. Many hundreds of drives are used in a body shop and a wide range of sizes of motor, although we standardised on a limited range of sizes of VFD to make the spares inventory sensible. The largest drive was for a 100hp motor for a body side turntable, probably a few tons of jigs being rotated and positioned in a few seconds. Something of a contrast from the oldest drive I ever worked on which was a Ward Leonard control for the table drive of a Stirk Planer, the control cabinet had a slate backplane the front panel door was a cast iron frame and glazed, the controls were brass handwheels. It was funny that this was probably from the 1920s or 30s and was next to a 1970s Droop & Rein numerically controlled mill that also used Ward Leonard control for the axis drives. Technology seems to be moving at a phenomenal pace and to have an electronic drive in a home workshop would have been unimaginable not so long ago and now even an industrial spec drive is within reach without needing super deep pockets and I suspect would be the best choice rather than the very cheapest option but even if the extraordinarily cheap version lasts a few years and does the job it could be happy days.

Mike

[EmgeeParticipant @emgee]

Mike

The VFD was mounted at around 4ft high and separated from the belt by a 3ft walkway, however the location IMO needed IP66 equipment which of course that VFD isn't, low pressure water used for clean down of the belt at the end of each of 3 8hr shifts.

Emgee

[Robert Atkinson 2Participant @robertatkinson2]

Steviegtr said:
" As for the home hobbyist needing to buy filters for the input i would say no. Not required. As an example I have a Dab radio sat on a shelf directly above my inverter, which i always have switched on. Never bats an eyelid "

Why did you say this? Are you just trolling?

EMC is not just about you. It's mostly about affecting others. How do you know that you are not interfering with aircraft navigation? Emergency communications? For example can you be sure that if an ambulance parked outside your VFD would not stop their datalink system or upset their ECG machine or other equipment?
You CAN'T.
As a minimum for your installation you might have done a quick sweep with a spectrum analyser but I doubt it. VFDs are typically used in an industrial environment and any internal filtering or external filtering recomendations are based on the allowable emissions for industrial. Hobby lathes are used in domestic environments. The allowable emissions for this are typically 1/10 of industrial (10dB lower. Exact levels depend on standard used, frequency etc). So to acheive the legally mandated emissions for home use methods such as additional screening and filters wil be required above those stated in the manual.

Suggesting even the minimum filtering is not needed is just irresponsible.

Robert G8RPI.

[Tony Pratt 1Participant @tonypratt1]

Robert, I have a problem with my milling m/c DRO in that when I switch it on it obliterates radio 2 so I'm guessing it's giving off EMC. Is there a simple filter I can fit to overcome this I guess complicated problem? I also see spectrum analysers are not too expensive, having said that maybe I was too hasty about the cost.

Tony

Edited By Tony Pratt 1 on 02/01/2022 19:14:39

[EmgeeParticipant @emgee]

From what Robert is saying best not to need an Emergency vehicle at work in a factory where there is no guarantee EMC precautions have been put in place, especially if they are allowed a much higher level of emission.

Emgee

[Robert Atkinson 2Participant @robertatkinson2]

My concern was an installation where not even the filters required for industrial levels were fitted. Not a compliant factory installation.

Robert G8RPI.

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