VFD Article in May issue 351

[Robert Atkinson 2Participant @robertatkinson2]

I’ve Just got around to reading the May issue (351) and the article on setting up a variable speed motor drive. There a couple of issues with this article. First and not a big issue is that it is a pit of an advert for Transwave. I does say it is written by Joe Jordan of Transwave. It would be interesting to know if they were paid for the article or was it sponsered by Transwave.

More impoertant is the lack of electrical safty information. These VFDs need to be in an enclosure. They are components, not finished products. The end of the article says “only undertake work if you are competent to do so.” This is a bit pointless as a competent person would not need the article…
Transwave have prominant wording on their website saying “WE MANUFACTURE AND SELL CE MARKED PRODUCTS COMPLIANT WITH EMC REGULATIONS, THE LOW VOLTAGE DIRECTIVE AND BS EN ISO 61000-3-2:2006” One problem with this is that BS 61000-3-2 only deals with current harmonics but at least it applies to domestic installations. The version quoted is out of date, the current version is BS EN IEC 61000-3-2:2019+A2:2024.
The IMO SD1 VFD featured in the article has a CE mark but it should not have one because it is a component. The only standard mentioned in the manual for the SD1 is EN 61800-3 (no version stated) which is for inverter drives. It has 3 categories (C1-C3) applicable to 240V / 415V equipment. Only C1 is applicable to domestic premises (or commercial with domestic on the same mains feed). Unfortunatly as supplied the SD1 does not meet EMC for any category. You need an optional EMC input filter for C2 or C3. It can’t meet C1 with the IMO optional input filter alone. So the arrangement desctibed in the article is not compliant with the EMC or Low Voltage Directives and is thus illegal.

And to top it off they have a picture of really poorly made off control wiring at the termnal blocks. There should not be that much copper exposed.

IIt really makes you wonder what they are thinking….

Robert

 

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, pretty poor example of connecting  wires to terminal blocks, and the Com one with the green and other wire in, is very bad. You wouldn’t think a well known outlet would show such poor workmanship.

Regards Nick.

[noel shelleyParticipant @noelshelley55608]

Some speak of the benefits of industrial technology coming into Model Engineering and hobby, but all to often as in this case it requires knowledge and more than the basic box of tricks to work satisfactorily. With often little used equipment from universities and colleges being available, usually 3Ph, for the average model engineer the electrical knowledge is lacking. Star to Delta and 220v or 415v, contactors and their coil voltages, forwards or reverse, inverters, converters Etc, the various questions on here illustrate the point. As Robert has shown, the CE mark is often meaning less. I have used a single phase Myford S7 for over 50 years, I have never suffered from any problem that was caused by the motor or power supply. Why would I want to use a VFD, ( I have a mitsubishi unit and Delta motor but have better things to do with my time than to do a job with little benefit )

Thankfully we don’t hear of electrocutions, MCBs and RCDs must work. Noel.

[halfnutParticipant @halfnut]

And there are two different CE marks that are confusingly similar. “Conformity European” and “Chinese Export”.

The latter is illustrated on the right below, and is not worth a cracker. It means nothing. But is deliberately deceptively similar to the real EU certification on the left. That may be how some dodgy components appear to be “CE” stamped.

[Robert Atkinson 2Participant @robertatkinson2]

There is no such thing as Chinese Export mark. Just non-compliant CE marks. Technically a non-compliant mark renders the whole item illegal. Some trading standards have used this to seize items without having to pay for an expensive technical evaluation. See https://cemarking.net/chinese-export/

There are lots of advantages to fitting a 3 phase motor and VFD to a S7 or similar lathe. Even wihout using variable speed you get smoother running and better finish.

Robert.

[Robert Atkinson 2]

On Robert Atkinson 2 Said:

There is no such thing as Chinese Export mark. Just non-compliant CE marks. Technically a non-compliant mark renders the whole item illegal. Some trading standards have used this to seize items without having to pay for an expensive technical evaluation. See https://cemarking.net/chinese-export/

 

Confirms what I said: “not worth a cracker”.

[Martin KyteParticipant @martinkyte99762]

Well I thought it was a useful article for anyone wanting to set up a drive. It showed what you got for your money, demonstrated it wasn’t that difficult and  showed that clear instructions were supplied. That and a brief overview of form and function covered all the bases. Quite honestly who cares who paid for it. There are many posts on here from people asking how to set drives up and the article answers many of their questions. Transwave regularly advertise in the magazine so nice to hear from one of their staff.

I agree that the control wiring was a little untidy and not as neat as I would expect of myself but wasn’t in itself hazardous.

[Robert Atkinson 2Participant @robertatkinson2]

The article is missing critical information on wiring the VFD safely. The then do a CMA  by saying only do it if you are competent.

VFDs are components, not a finished product. They need other components to make a safe system.

Robert.

[Martin KyteParticipant @martinkyte99762]

Perhaps you would like to say what the missing information is then Robert.

regards Martin

[Robert Atkinson 2Participant @robertatkinson2]

Requirements for isolator (could be an IEC C13/14 inlet on enclosure), fuses, earthing, cable type and sizing, strain reliefs/glands, EMC filters and most importantly an enclosure.
They mention a 4 core cable for the motor and a possible earth terminal but no guidance how to connect it. For a start ring tags should be used on the connections.
On the poorly stripped fitted control wires, as these are part of the supplied control pendant it is surprising that it is not supplied with bootlace ferrules already installed. They are not hard to find, even Lidl have them.

Robert.

[Martin KyteParticipant @martinkyte99762]

Hi Robert

All of what you say is fair comment but just a few comments if I may.

The article is titled setting up the drive rather than detailing the full installation.

The Inverter can be bought as an item or Transwave sell the complete package.

The article seems to refer to the package where you get all the correct size cabling and full data sheet and instructions for installation. If I remember correctly the motor cable came fitted with ring tags. The inverter terminals are cage clamp type rather than single screw so do not damage the wires if the user chooses not to employ ferrules.

The system is intended to run from a standard 3 pin plug so an isolator is not a requirement as such.

The article does say that the inverter needs to be protected from swarf/dust ingress and on all the data sheets I have from the inverters I have bought it always says an enclosure is recommended in areas where that is likely to occur. The inverter however is fully shielded terminal wise and can be mounted as quoted in a clean and cool place. I have one mounted high up on the wall in my workshop operating an overhead drive motor giving me no trouble.

Thats about all I can say really.

regards Martin

[Robert Atkinson 2Participant @robertatkinson2]

Hi Martin,

Running of a 13A plug does not remove the need for an isolator. This could be a No-Volt release type E-stop on the supply. Really needs a safety assesment but they are so cheap just fit one. The cables need proper support and the terminals must be touch-proof even with covers removed (unless a tool is requred to remove the cover and it is robust). If the user can see or touch the blue, brown or green/yellowinner insulation of the mains cable it is unsafe.
Was a mains input filter supplied? For the SD1 tis is required even for an industrial location. The one available from IMO is not adequate for domestic locations. The VFD does not have a filter built in as in a multiple drive installation there might only be a single filter required.
You CANNOT make a Jaguar CUB, SD1 or similar VFD meet the applicable safety directives without putting them in an enclosure with additional filtering. Transwave are carefully “passing the buck” by only supplying a set of parts. As the installer it is your responsibility to compy with the directives. And no, it does not matter that it it is only fory your own use and you are not selling it. You are “putting it into use” so are responsible for compliance. As a minimum you have to comply with the LVD and EMC directives and possiby the machinery directive.

[Martin KyteParticipant @martinkyte99762]

Pull the plug out and it’s isolated.?

As I say you are not wrong in what you say but I think you are over egging things a little bit.

Lets face it Myford sell pre wired lathes with these drives and I don’t see anyone making too much fuss about EMC compliance.

[John HaineParticipant @johnhaine32865]

Actually I think Myford fit a Newton Tesla unit which embeds a Mitsubishi inverter in a box with filters etc.  When I enquired about opening the box to connect speed control and estop from the cnc controller they said it would invalidate the emc approvals as well as the warranties.

[Robert Atkinson 2Participant @robertatkinson2]

Pulling a 13A plug is OK as long as it is visible to anyone working on the machine and clear what plug is is connected to what unit. This applies even if you are the only user in the workshop.
Can you honestly say you have never plugged in or unplugged the wrong plug? I can’t

My answer is to fit a IEC C13/C14 connector aka kettle lead at the mains inlet to the box containing the inverter. Easy to see before you open the box etc. Solves the strain relief issue too.
Minimal cost, simple – just do it.

Robert.

[EmgeeParticipant @emgee]

Martin

I agree that removing the 13A/16A plug at the point of supply can be classed as “a means of isolation” and is considered to be the preferred method in many cases. In those instances where it is not considered suitable an isolator with lock off facility shall be provided.

I also agree with your view on fitting a VFD in the workshop provided it is of IP20 or better rating and conditions at the point of fixing will not present a hazard to the unit, of course the cables shall be supported and teminated into the VFD connection point in a safe manner.

The myth that the buttons on the VFD are only for the setting up process is IMO just nonsense.

Emgee

 

 

[Martin KyteParticipant @martinkyte99762]

Some helpful information in the last few posts. Including the IEC socket on any enclosure. I think we should aim for helpful rather than risk frightening people off. As I say Robert is not wrong but I found it a good article.

 

 

 

[not done it yetParticipant @notdoneityet]

One of the bigger issues with most VFDs is that none of the high voltage conductors have any form of cable restraint.  That alone should make it obvious that those VFDs should be inside a secure enclosure.

[not done it yet]

On not done it yet Said:

One of the bigger issues with most VFDs is that none of the high voltage conductors have any form of cable restraint.  That alone should make it obvious that those VFDs should be inside a secure enclosure.

Well-said ^^^

MichaelG.

[Andrew CrowParticipant @andrewcrow91475]

I would totally agree with “notdoneityet” on a previously owned machine I fitted a “Cub” not only lacked any cable restraints but the terminal block was also exposed. Although it was fixed to the wall behind the machine there was still a risk.  More  recently I have fitted a Newton Tesla pre- wired system on my S7.

If I were to use separate components again I would certainly use some form of enclosure with a remote pendant.

Andy.

[Michael GilliganParticipant @michaelgilligan61133]

To give Joe Jordan his due: He does mention an earlier article based on the Jaguar Cub [it’s in MEW 259] and the current one is highlighting the setting-up of new unit.

That said, the first article was similarly lacking in regard to installation safety.

MichaelG.

.

P.S. __ On Topic … I hope everyone remembers the old joke response to:

“ What has a HazelNut in every bite ? “

[Robert Atkinson 2Participant @robertatkinson2]

Martin,

IP 20 is only protection against ingress of items over 1.5mm. There is no protection against dust or moisture. Thia is clearly not adequate protection for use in a workshop with machine tools. This is particuarly true if you are using the front panel controls. If you can reach it so can swarf.

The controls on the front of a VFD are only intended for set-up and trouble shooting. It’s not a myth.
1. They are not durable enough.
2. They are too small (in most cases) to allow accurate location especially in an urgent situation.
3. They make you put your hand, which may be wet or have loose swarf on a mains unit with inadequate protection.
4. using them means you can’t have the VFD in an enclosure which is required for EMC and physical protection.

Robert.

 

[HollowpointParticipant @hollowpoint]

While we are on the subject of VFD controls, does any know if one of these can be used in parallel with the normal push buttons/pendant?

I would like to have both on my lathe.

[Hollowpoint]

On Hollowpoint Said:

While we are on the subject of VFD controls, does any know if one of these can be used in parallel with the normal push buttons/pendant?

I would like to have both on my lathe.

Looks like the setting of P12 for the Invertek drive can give one or the other option, not both together.

[Michael Gilligan]

On Michael Gilligan Said:

On not done it yet Said:

One of the bigger issues with most VFDs is that none of the high voltage conductors have any form of cable restraint.  That alone should make it obvious that those VFDs should be inside a secure enclosure.

Well-said ^^^

MichaelG.

The cables can be adequately supported very simply by the installer.

There is no high voltage present in these cases, check the definition for further info.

 

Emgee

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