vfd inverter for Myford

[old martParticipant @oldmart]

With regards to EMC which some VFD's have and others don't, the Sneider Altivar which I bought has EMC which can be disabled if required. As the mill is in a museum, I chose to keep the EMC enabled, just in case there were any legal requirements. Having EMC enabled does result in a measurable earth leakage, but I was relieved to find that it was not enough to trip the RCD protected supply. As the EMC is intended to reduce RF interference, in association with proper shielded cabling, there is a small risk of causing local problems with Wifi, tv's, radio, phones, and maybe heart pacemakers, and doorbells.

The self contained programming makes sense when you understand that the vast majority of VFD's are set up for automatic machinery, and left untouched. Anyone thinking that they could stop a machine in an emergency using the tiny stop button on the VFD as easily as hitting a full sized and correctly positioned emergency stop button is sadly lacking in common sense.

Using the controls from a scrap washing machine has possibilities, but the system is designed to be used with the original motor, and might not be compatible with other motors.

Edited By old mart on 23/11/2020 15:15:56

Edited By old mart on 23/11/2020 15:21:11

[Ex contributorParticipant @mgnbuk]

Firstly why do manufacturers produce VFD's with control switches on the front panel

To aid comissioning.

and provide an IP rating that conforms with use in a home workshop environment without further protection. ?

Inverters are usually IP20 – effectively little more than finger insertion proof. They are designed to be installed in a suitably protective enclosure.

Clearly because it is a self contained motor starter with speed control.

Nope. They are a system component.

Provided the VFD is CE marked it has already been certified by the manufacturer to comply with the Low Voltage Regulations.

Inverters are not CE marked – they are components to be built into a system & then the whole system checked for conformity.

If users wish for their own reasons to mount the VFD in an enclosure and add a remote control station that is their choice.

If all else fails – read the manual that accompanied the device. I have not come across an inverter yet that doesn't require fitting in a suitable enclosure. If you choose to ignore the manufacturer installation requirements that is your choice – maybe best, though, not to push that as best practice.

Nigel B.

[EmgeeParticipant @emgee]

If all else fails – read the manual that accompanied the device. I have not come across an inverter yet that doesn't require fitting in a suitable enclosure. If you choose to ignore the manufacturer installation requirements that is your choice – maybe best, though, not to push that as best practice.

Nigel B.

Start here to find out more about installation, nothing there about enclosures.

**LINK**

Check the rest of the manufacturers information if you have the time.

Emgee

[SillyOldDufferModerator @sillyoldduffer]

Posted by Emgee on 23/11/2020 14:17:19:

…

Firstly why do manufacturers produce VFD's with control switches on the front panel and provide an IP rating that conforms with use in a home workshop environment without further protection. ?
Clearly because it is a self contained motor starter with speed control.

Provided the VFD is CE marked it has already been certified by the manufacturer to comply with the Low Voltage Regulations.

If users wish for their own reasons to mount the VFD in an enclosure and add a remote control station that is their choice.

Emgee

Although the VFD inside my lathe is reasonably well protected, it's enclosure is insufficient in that the terminals can touched accidentality and swarf could get through the cooling vents. Although fitted with a front panel that does all an operator needs, the panel isn't intended for grubby fingers on a regular basis. It's purpose is configure and test the VFD during set-up and maintenance.

I can't speak for all VFDs but mine, like the similarly protected contactor, is clearly a component meant to be mounted inside a box and wired to switches and a pot safely separated from the user. All the cheaper and mid-range VFD's I've looked at were components too, not meant to be used in an open workshop.

As botched home electrics go, I wouldn't put a cheap VFD top of my list. Better safe than sorry in my view though especially if the workshop has visitors. How difficult would be for an inquisitive child to poke terminals with a little finger?

John asked about Washing Machine Filters. Unlikely to be all that effective but should help a bit and wouldn't do any harm provided the one used can take the amps. I've thought of trying it.

I can confirm comments about the inadequacy of domestic radios to detect RFI. DAB and FM both have strong signal characteristics – they're deaf to anything less powerful than the station they're tuned too, and also only listen in the VHF range. An old AM radio is  better, but testing EMC really demands the right equipment.

Picture below is a slice of medium wave with the VFD on, but the motor off. The centre spike with fluffy sidebands in the lower pane is a local AM radio station, happily straddled by two powerful VFD noise peaks (one inside the green box.) These can only be found by tuning the radio to them.

Driving the motor makes the interference much worse, effectively zapping the whole medium wave:

Due to equipment limitations the images only show interference over a tiny part of the radio spectrum. Checking further shows my VFD puts out serious noise spikes all the way from about 25Hz to 150MHz. Not asked my neighbours if they have internet problems when I'm in the workshop, but …

Dave

PS. After capturing the images I reduced the problem somewhat by fitting a shielded cable between motor and VFD. It's far from fixed though. I'd sort it properly if I used my lathe more often, only used it for less than an hour in the last week, so its unlikely to be a major nuisance. I hope!

 

Edited By SillyOldDuffer on 23/11/2020 17:38:02

[old martParticipant @oldmart]

The Inverter Drive Supermarket quick start guides always stress the importance of shielding. I used shielded wiring for the VFD to motor, the potentiometer and the remote emergency stop switch, and the steel box containing the inverter is earthed, including its door.

[Mike PooleParticipant @mikepoole82104]

seems clear that it should be in a enclosure or electrical area.

Mike

[Ex contributorParticipant @mgnbuk]

Check the rest of the manufacturers information if you have the time.

Siemens manual for Sinamics V20 inverter

Section 3 Mechanical installatiion, Sub section 3.1 Mounting Orientation & clearance :

"The inverter must be mounted in an enclosed electrical operating area or a control cabinet"

Seems quite clear to me ?

Section 5 Commissioning via the built in Basic Operator Panel seems to confirm that the BOP is primarily a commissioning tool.

Nigel B.

(sorry about the font change – cut & paste from the .pdf changed it and I can't see how to change it back).

Edited By mgnbuk on 23/11/2020 19:51:49

[Robert Atkinson 2Participant @robertatkinson2]

Emgee,

It's not "doom and gloom" it's sensible advice from a professional. I see others have responded to your comments so I won't say more about that.

As I've said before what you do in your workshop is your business, but when anyone suggests doing something dangerous and/or illegal to others or states that good guidance is wrong I have a moral (and professional) obligation to make comment.

One thing I will add is the the manuals for VFDs assume, and normally state, that the installation design and work is carried out by a suitably qualified and experienced person (SQEP). I happen to be a SQEP for both the design and installation of VFDs and similar, you do not appear to be.

Doing installations in work or public areas like "Mens Sheds" and museums is a bit different. These normally have public liability insurance and it is worth looking at the "small print" they may have conditions limiting who can do things like electrical work.

Robert G8RPI.

[EmgeeParticipant @emgee]

Robert

Unlike you I don't shout it from the rooftop but I am a SQEP to design and carry out electrical installation and maintenance but now happily retired after running my own electrical installation and maintenance business for 34 years.
I gather from your comments over time you are electronically orientated and have very limited knowledge of electrical installations.

Emgee

[PeroParticipant @pero]

A query if I might.

In the discussion on VFDs the subject of EMC filters is regularly raised.

As one who prefers not to interfere with others I am quite happy to fit one BUT I have yet to see any comment on what type of filter is required ( there are EMC filters and there are EMC filters ). It needs to meet both legal requirements ( if any ) and to do the job it is there to do.

If it is the small metal encased type costing a few dollars ( or pounds ) I am quite happy to fit them whether needed or not. However if it is the massive type costing a great deal more than a high quality ( i.e. expensive ) VFD then I need to know that the expense can be justified ( i.e. is there really a problem that needs fixing ).

Any advice from the suitably qualified – by training or experience – would be welcomed.

On the subject of enclosures – a good idea even if the VFD is located some distance from the machine. It is amazing just how far swarf will travel, especially aluminium, and where it will end up. Quite a few CFDs have an inbuilt fan which will draw air ( and light swarf ) into the internals with possible sad results. An enclosure will also provide protection against the odd flying missile – broken tool, chuck key etc.

Pero

[SteviegtrParticipant @steviegtr]

Omron Mini J7 Installation notes.

Installation Direction and Dimensions

Install the Inverter under the following conditions.

• Ambient temperature for operation (panel-mounting): -10°C to 50°C

• Humidity: 95% or less (no condensation)

Install the Inverter in a clean location free from oil mist and dust. Alternatively,

install it in a totally enclosed panel that is completely protected from floating

dust.

If the Inverter is installed in an enclosed environment such as a box, use a

cooling fan or air conditioner to maintain the internal air temperature below

50°C. The life of the built-in electrolytic capacitors of the Inverter is prolonged

by maintaining the internal air temperature as low as possible

The J7 Inverter meets the EC Directives and UL/cUL standard requirements

for worldwide use. Directives EMC Directive EN50081-2 and EN5008-2

Low-Voltage Directive, prEN50178 ,UL/cUL UL508C.

Installing a Noise Filter on the Power Supply Side.

The Inverter’s outputs uses high-speed switching, so noise may be

transmitted from the Inverter to the power line and adversely effect other

devices in the vicinity. If this causes interference then, it is recommended that a Noise Filter be

installed at the Power Supply to minimize noise transmission. Noise will also be reduced from

the power line to the Inverter.

I cut & pasted this from The Omron inverter manual. I never said you could not use a enclosure or a filter.

The point i was making is that there is no Law that requires it.

Also an EX now retired Electrical contractor of over 50 years in industry.

Steve.

 

Edited By Steviegtr on 24/11/2020 15:34:29

[old martParticipant @oldmart]

Anybody can use the VFD for home use without any extra switch gear,or covering, if they want to. I had to at least pay lip service to health and safety with the one I installed at the museum for obvious reasons.

[Ex contributorParticipant @mgnbuk]

Omron J7 manual

The manual above says this WRT mounting :

Be sure the Inverter is protected from the following conditions.

• Extreme cold and heat. Use only within the specified ambient tem-perature range:−10 to 50 °C (14 to 122 °F) for IP20 (open chassis type),−10 to 40 °C (14 to 105 °F) for NEMA 1 (TYPE 1)

• Rain and moisture

• Oil sprays and splashes

• Salt spray

• Direct sunlight (Avoid using outdoors.)

• Corrosive gases (e.g., sulfurized gas) or liquids

• Dust or metallic particles in the air

• Physical shock or vibration• Magnetic noise (Examples: Welding machines, power devices, etc.)

• High humidity

• Radioactive substances• Combustibles, such as thinner or solvents

In the specifications section of the manual the device is described as "open chassis" – which is described as IP20 above. I don't see how the environmental requirements described above can be met with an IP20 device without enclosing it ?

Nigel B.

[Robert Atkinson 2Participant @robertatkinson2]

Posted by Emgee on 23/11/2020 22:50:41:

Robert

Unlike you I don't shout it from the rooftop but I am a SQEP to design and carry out electrical installation and maintenance but now happily retired after running my own electrical installation and maintenance business for 34 years.
I gather from your comments over time you are electronically orientated and have very limited knowledge of electrical installations.

Emgee

There lies the rub, a VFD is not electrical installation, it is electronic equipment / system design.

To properly and legally install a VFD of the type we are discussing (other than in an industrial "fixed installation" (which has a specific meaning) the finished product MUST comply with the relevant direcives (CE or in UK from 1st Jan 2021 UKCA) This as a minimum includes the Low Voltage Directive and the EMC Directive and in many cases the Machinery Directive. The electrical installation and BS 7671 ends at the socket on the wall.
Yes I'm primarlly electronics (avionics to be precise) but I have done domestic and light industrial installation work and a lot of equipment design and manufacture.
Came across this at work recently. Had a mains motor in a box with a solid state relay. The non-aircraft electrical people said "we have done it to "edition 18" I questioned this, but becuase I'm avionics (person involved did not know my background) they asked an outside certification expert – who confirmed exactly what I said – LVD and EMC Directive. They even chose the same harmonised standards I had.
The very fact that you don't think this is required shows you are not a SQEP.

Just because lots of people don't comply and enforcement is virtually non-existent does not make it right.

[Robert Atkinson 2Participant @robertatkinson2]

Posted by Pero on 24/11/2020 03:47:23:

A query if I might.

In the discussion on VFDs the subject of EMC filters is regularly raised.

As one who prefers not to interfere with others I am quite happy to fit one BUT I have yet to see any comment on what type of filter is required ( there are EMC filters and there are EMC filters ). It needs to meet both legal requirements ( if any ) and to do the job it is there to do.

If it is the small metal encased type costing a few dollars ( or pounds ) I am quite happy to fit them whether needed or not. However if it is the massive type costing a great deal more than a high quality ( i.e. expensive ) VFD then I need to know that the expense can be justified ( i.e. is there really a problem that needs fixing ).

Any advice from the suitably qualified – by training or experience – would be welcomed.

On the subject of enclosures – a good idea even if the VFD is located some distance from the machine. It is amazing just how far swarf will travel, especially aluminium, and where it will end up. Quite a few CFDs have an inbuilt fan which will draw air ( and light swarf ) into the internals with possible sad results. An enclosure will also provide protection against the odd flying missile – broken tool, chuck key etc.

Pero

Very good question.

Practically you use the filter included with the VFD or that recommended by the maker of the drive. Even this is not certain to comply, in theory you have measure the emissions (conducted and radiated) from the equipment over the applicable frequenct range (typically 200kHz to 1GHz). and ensure it is below the limit.
As you might expect very few people do this for a single installation.

If he VFD supplier does not provide a filter or suggest a suitable one you have to use professional judgement, the rating of the drive and other information to choose a likely filter and then you have to test it with your equipment.

Robrt G8RPI.

[SteviegtrParticipant @steviegtr]

Edit

Steve.

Edited By Steviegtr on 24/11/2020 18:05:52

[SteviegtrParticipant @steviegtr]

I think i may have been a bit wrong with comments about filters. This is an insert from Inverter supermarket site. My inverter has an inbuilt EMC filter & i as always use screened & earthed at one end motor cable. It seems some imported versions from ???? have not got the required filters built into them.

Steve.

It is more important to use motor wires that are screened, armoured or completely encased in metal conduit. This reduces the leakage of EMI and offers a conductive path back to the Inverter (required for EMC compliance in any case).

The Parker SSD Drives products we sell up to 7.5kW all include EMC Filters to the First and Second environment, as long as they have '-F-' in the product code. Most of the others include Second Environment filters, unless they say otherwise.

[Robert Atkinson 2Participant @robertatkinson2]

One thought for those who have had RCD trips from VFDs with filters – what was the leakage current BEFORE you added the VFD?
A typical household RCD trips at 30mA (differential between live and neutral currents). But a EMC filter leakage to earth (caused by the "Y" capacitor(s) is less than 1mA for a simple filter, about 5mA for a VFD filter or 15mA for a high performance filter. Given these figures even a high performance filter should not cause a trip. It is likely that the existing wiring and equipment has used up most of the leakage "allowance" and the VFD filter pushes it over the edge. Not if the existing current is from filters, that's not too bad, but it could be due to degraded wiring (for example google "green goo cable&quot.

If your VFD filter trips the RCD it might be time to get a competent electrician to check the house wiring.

Robert G8RPI.

[Mike PooleParticipant @mikepoole82104]

Probably not a problem these days but CRT computer monitors are a bit leaky, an office had five fed from one RCD that would hold any four but all five would trip, for some reason a 10mA trip was fitted so it was super sensitive.

Mike

[SteviegtrParticipant @steviegtr]

Way back we had to excuse quite a lot of office equipment from the PAT test leakage test, due to a lot of equipment having padding capacitors around the chassis ,connected to earth. We used to get some weird readings.

After contacting the aapropriate manufacturers of the equipment we skipped the leakage test as directed by the Electrical engineers at the Blue chip companies we contracted to.

Note to oneself put all your Inspection & testing meters on fleabay.

Steve.

[AJAXParticipant @ajax]

Posted by Andrew Tinsley on 20/11/2020 23:06:49:

If you are unsure of VFDs then don't buy a cheap Ebay Chinese VFD. They do work but need some experience to decipher the very poor documentation

Take Old Mart's advice and get a VFD from Inverter Drive Supermarket. Phone them up and ask for a recommendation.

I buy secondhand Siemens 420/440 or Alytivar VFDs , These are good quality units with excellent documentation and cost only a few pounds more than the Chinese VFDs I have installed 5 units so far with no problems.

Andrew.

Andrew, do you suffer any nuisance tripping with the Siemens VFDs? I considered getting one but the documentation states to avoid nuisance tripping an RCD must be type-B 300 mA. The RCD serving my garage is only 30 mA and I do get occasional nuisance tripping with a Eurotherm VFD.

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