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Member postings for Robert Atkinson 2

Here is a list of all the postings Robert Atkinson 2 has made in our forums. Click on a thread name to jump to the thread.

Thread: Inverter interference
22/02/2022 20:06:15

Go back to the vendor of the lathe and ask them to fix it or provide details of the EMC qualification.

Robert G8RPI.

22/02/2022 19:46:38

If it is aood quality drive by a well known manufacturer, follow their installation recommnedtions.
If some unknown far eastern item with minimal or pooly translated manual you are left with guessing.
Basically you will likely need to:

Install the inverter in a metallic enclosure
Fit a high performance EMC filter at the mains input to to the drive.

Keep th cable to the motor as short as possible and ideally use some kind of shielded cable SY flexible armued cable is a goodd compromise e.g.

Lacing advice from drive manufacturer dround the shield/armour at the "wall" of the metallic box enclosing the drive. Metallic cable glands designed for this are available. keep it insulated at he motor end (use a plastic strain relief) and ground the motor housing with the fourth core in the cable.

Use screened cabble for ny control pendant or similar.

That's mid-level good practice.

Robert G8RPI.

Thread: Plasma cutter at lidl
20/02/2022 16:34:59

Peter R.
According to the manual the Parkside PPSK 40-A1 conforms to EN55011 (basically same as CISPR 11) Class A. Class A devices are heavy industrial and are not allowed to be connected to the same supply as any domestic premises. So unless you have your own feed to the electrical substation or transformer, seperate even from your own house, It is technically illegal to use it.
The manual also references IEC 61000-3-12 which relates to harmonics. The manual states the cutter is only compliant for harmonics if the supply impedance must be less than 0.024 ohm. Well actually the manual is obtuse and refers to the short circuit power as 2446.7 kW miimum. From this we can calculate the current (>10,000 A) and impedance. This is a totally unrealistic impedance for a domestic supply (except perhaps for some parts of London which have a grid distribution scheme) If the cable from the main feeder in the road is more than 30 feet there is no way you can reach this low an impedance.
The harmonics generated can damage other equipment on the supply as well as causing interference.

It is at best poor practice by Lidl to sell this in retail outlets. The warning and conditions in the manual are meaningless to the average purchaser.

Robrt G8RPI.

Edit, a more appropriate EMC standard would be IEC 60974-10 but that still references EN 55011 and the cutter would still be class A. It probably would not meet all the requirements of 60974-10

Edited By Robert Atkinson 2 on 20/02/2022 16:45:08

19/02/2022 23:31:47

Peter R.
It IS illegal to use it on a domestic supply bceause it does not meet the electromagnetic emissions standard for domestic environments. Even the manual says this, but not in plain language.
You are unlikely to see any enforcement though.
My main issue is with Lidl sellin these in a domestic retail outlet.
I sked them abou this but have had no response......


Thread: What are these connectors called?
19/02/2022 19:15:56

+1 for JST connector.
Theise need specail crimp tools.
An alternative is 0.1" pithch headers. The Amercans call them "dupont" Connectors. Try a seach on your favoite online market for dupont connector kit

Robert G8RPI.

Thread: Front door locks
19/02/2022 13:53:37

You can get an electric release striker plate / box for either mortice or surface (Yale) locks.

Get a fail-locked one and connect to an electronic entry pad. Keys work as normal and pad releases the electrical.
As an added precaution when out a disable switch can be fitted. This prevents carers etc gaining access whenyou are out. If worried about leaving it off, a door operated switch with a spring or hinged toggle can be arranaged so you can turn it off (towards door) and door passed it but when you open thee door it is switched back on automatically. Fit to jamb just above head height.
If you are carefull with the geometry an ordinary toggle switch can be made to work. Or a magntic reed switch on the door, push button for disable and a relay can be arranged for an electrical solution of a disable that automatically resets.

Robert G8RPI.

Thread: Plasma cutter at lidl
18/02/2022 15:04:06

As stated previously, running these off a 13A socket, by changing the plug or using an adaptor, is illegal.
So is using it in a residential area.
Enforcement is virtually non-existent though and you will probably never know who you are causing interference to.sad

18/02/2022 13:03:05
Posted by Pete. on 18/02/2022 00:27:30:

There's a video on YT where a German guy takes the cover off this model and discusses the components inside, his general concensus seemed to be for a budget machine it was pretty good, so I decided to get one.

I went to Wigston LIDL first, they didn't know anything about it and no sign it had ever been put out for sale, gave their helpline a call and their policy is that they do not give out any information as to which stores have certain items listed on their website.

In an age where we're charged for plastic bags to save the environment, telling customers to aimlessly drive around and just hope where they go has some in stock seems ridiculous.

I nipped over to Hinckley and they had loads in stock, haven't tried it yet but the build quality seems pretty decent.

What type of 16A plug, an industrial round 3 pin with blue body or "Euro" with 2 pins and side contact for earth?

13/02/2022 19:35:27
Posted by Howard Lewis on 13/02/2022 15:58:35:

The VFD for my lathe is fed from a suppressed double 13A socket, to ensure that, whether or not the VFD has internal suppression, little or nothing hasty can get back up the mains to affect any of our electronic devices, or those of any neighbour on the same phase.

If I bought this plasma cutter, it would be fed from the vacant socket in the same hope.


Hi Howard,

A vain hope unfortunatly. A "suppressed" socket is likely to only have voltage spike suppression not emissions. In any case the length of the mains lead will negate a lot of the effect even if RF filtering is included.
With the plasma cutter no amount of mains filtering will reduce emissions from the torch.

Robert G8RPI.

13/02/2022 19:29:15
Posted by Clive Foster on 13/02/2022 15:36:29:

I think Robert overstates the practical implications of the issue.

Most likely, as with so much affordable equipment out of China, its never been tested. Assuming halfway sane design its going to be at least close to the regulations and probably inside them for normal use. With EMC its generally the edge cases that catch you out with excessive emission if the basic design is sound.

If it really is well out LiDL are liable under the wider sales of goods act provisions as its not suitable for the purpose its sold for and is misleadingly described. Needs at least a big "for industrial use only, not to be used in a domestic environment" banner on the box to get out of that one. Anything in a supermarket has to be considered consumer goods and any outfit the size of LiDL has to be considered an expert supplier.

Be most interested to see what the version sold in German stores has to say about itself.

I do wonder if there is a suitable "universal" filter that can go on the workshop (or house) incomer to stamp out anything trying to go back upstream to the supplier. VFD driven washing machines et al are becoming more and more common. Not to mention umpteen (cheap!) switch mode power supplies which can be worse. Solar panel inverters probably aren't blameless either.


Hi Clive,

It's nothing to do with the sale of goods act. It is about radio and electrical interference. If the unit has not been tested then it as illegal to sell or use in the UK or EU. You cannot confirm compliance with this type of equipment without testing. Lidl / Parkside claim compliance to a INDUSTRIAL specification. This is why it is illegal to us it in a residential setting.
As I said before enforcement is minimal and the likely intermittent nature of use makes it unlikely to be located.
Still does not mke it right and in particular Lidl should not be marketing them to hobbyist users.

Robert G8RPI.

13/02/2022 14:51:30

It means it's illegal to use it in a domestic or light industtrial setting. Looking at the CE declaration in the manual the EC compliance is to IEC 60974-1 This is a industrial / professional tandard that allows higher emissions.
At best it is disenginious of Lidl, it's probably illegal to sell this to the general public in a retail store (I'm a EMC expert not retail law) The only excuse they may have is if it is supplied with an industrial 16A plug fitted. As soon as a customer replaces that with a 13A plug Lidl are off the hook. If it is suppied with a european 16A plug fitted it is illegal to sell in a retail outlet.
It is noticable that the advert does not show the plug, specify what plug is fitted or what the current / power consumption is. Even the manual does not specify the input current / power.

My professional opinon is that it is illegal and possibly unsafe to use this equipment in a residential or domestic environment. Even if you have a 16A outlet or 3 phase supply in your workshop. If it is in a residential area the interference emitted make it illegal.

Robert G8RPI.

Edit: Andrew's reply came in while I was typing. While what he says is true, I hope he will agree that it is still illegal even if  enforcement is non existent.. I also doubt Andrews equipment was bought in a retail outlet. 
Driving at 33 in a 30 mph zone is illegal even if you are not stopped for it.


Edited By Robert Atkinson 2 on 13/02/2022 14:56:40

Thread: EMCO FB2 origin drift due to heat
12/02/2022 22:03:51

I once designed the electronics for some 3 axis machines that placed biological samples that were subsequently scanned. Distortion in the pattern was caused by temperature changes including diurnal. These machines were running Renishaw encoders with 1 micron (0.001mm) resolution. We had to accuratelymeaure the temperature of key part of the machine and use software compensation. We used a Renishaw laser interferometer to measure the position of the moving head for calibration. Fortunatly we did not have to do every machine.
For a simple structure it's straightforward to calculate the change in size with temperature. The structure of Concorde got so hot special measures had to be take to allow for it. Most often quoted, but not most important, was elasic carpet in the cabin.

Robert G8RPI.

Thread: Right to Repair
10/02/2022 21:32:48

On swappable batteries, unless there is a common design thre will either never be enough stations for some models or the stations will have to stock different types. And as mentioned there are issues with ownership, life and warranty. When batteries were so expensive thry were leased it might have been an option.

On Nick Clarke 3's question on chargers. If its for employees who are on site for several hours, don't install "chargers". Instead provide 13A (16A in europe) outlets and let the car owners use their 3kW "granny" chargers. You don't need a fast charge if you are parked all day. A 8 hour charge will give at least 50 mile range even on larger cars. This is enough for most commutes. A twin RCD protected 13A socket will serve two spaces and cost a lot less than a 32A 7kW charger that will only supply one car.

Robert G8RPI.

09/02/2022 17:44:29
Posted by Hopper on 09/02/2022 10:03:35:

The next generation of electric cars will have quick change battery packs that you just pull into the service station and they yank out the flat battery and drop in a charged one about as quick as filling up a petrol tank, maybe quicker. They are already doing it on long haul electric trucks in Australia, with the battery change stations at the drivers' fatigue break stops. And motorcycle manufacturers are already working on a standard changeable battery pack across all makes and models. Car manufacturers are not far behind doing the same.

But yes, will need a lot of windmills and solar panels to power it. But we are already well on the way with solar in Australia, to the point that power prices are forecast to go down in the very near future and coal power stations are closing down ahead of schedule.

But of course we have the almost limitless space and sunshine for massive solar "farms". And suburban rooftop solar is so ubiquitous it is threatening grid stability with an oversupply of power at times. If only you guys could capture rain power instead of solar!! laugh

Hmm, I don't think so. Cars need custom battery packs due to space constrints. Unless they are all going to look the same. Commercial vehiles aere a different use case.
Do you have any examples of cars with quick-change battery packs?

Robert G8RPI.

Thread: Underfloor heating
06/02/2022 21:33:26

A little context would help
I assum you are talking heatpumps. Generally, yes underfloor heating heats the floor to warm underfoot and that heats the ret of the room.
We have electric underfloor heating in two areas of the house and it works well. Main heating is air-air heat pump (2 outdoor units 5 indoor) that alos pprovides air conditionng in summer.
The house was built witth "ceiling heating". This comprised foil heating elements behind the plasterboard forming the ceilings. No it does not work heat rises and white ceilings don't radiate well. The previous occupants had resorted to portable heaters....
Air-Air heat pumps are great but you don't get a grant for them because of the airconditioning capability.

I'm not sure about air-water ones when keeping existing radiators. The radiators were designed to work with hotter water than the heat pumps can create efficiently. Using underfloor heating with them seems much more reasonable. Lower temperature but larger surface area for same energy.
One disabvantage is you could loose a bit of headroom due to the thickness of pipes and insulation required.

Robert G8RPI.

Thread: Green growth on car roof rails
06/02/2022 17:29:21

I suggested benzalkonium chloride because:

A. It is safe and non-persistent. Other uses include throat lozenges and preservative in eye drops. LD50 for Rats is 2 g/kg (table salt is 2 g/kg). Just keep it out of the fish pond.
B. It isintended for use as an algicide. The Dettol product is a different application but is sold in a more useful 250 ml rather than 2.5 l for patio cleaner.
C. it does not damage paintwork or rubber seals e.g. around windows.
D. It's non staining

Robert G8RPI.

06/02/2022 16:21:47

Best treatment for this is benzalkonium chloride. A detergent and biocide. Available in several forms including patio cleaner. I use Dettol's washing machine cleaner as a source. Dilute 50:50 or 30:70 with water and spray or brush on the green stuff Leave for a few hours and wash off. Helps prevent re-growth.

Robert G8RPI.

Thread: Possible Myford 7 safety issue
03/02/2022 21:11:28

For electrical safety only exposed metalwork (conductive items) which could become live due to a failure of "basic insulation" need to be connected to the protective conductor "earth".
So if the mains cable goes directly into an enclosed (apart from ventillation holes) motor only the motor needs to be earthed. This is because the current can't come through an earthed motor housing make the lathe (or whatever) live. Note the lathe may coincidentally be earthed via the motor mounting. If the mains goes via a switch mounted on a metal stand then the stand should be earthed. Unless the switch is enclosed in a earthed metal box or a insulated box. Note enclosed includes the back of the box and having proper cable entry and exit protection by glands or approved mains connectors.
An old style "Dewhust" reversing switch is a special case in point. Many only have a single screw securing the cover. They have an earth connection for the base but the cover is floating. A credible accident scenario is screw comes loose and the operator fiddles with cover and it touches a live part. To meet sensible standards the cover needs an earth lead.
Fitting a mains powered work light to the lathe or metl stand may require additional earthing, particuarly if the lamp was not intended for this aplication.
This is of course separate from any earth requirments to prevent interference.

Robert G8RPI.

Thread: Smart TV
25/01/2022 19:31:34
Posted by Howard Lewis on 25/01/2022 14:31:38:

If you can find a cable with a HDMI connector one end and three Phono lpugs on the othere, you can feed the Audio and Video output from the player into the TV

The TV also has Phono sockets on the back. Are they for Input or Output?

If for Input, three Phono leads should do the trick.


If you find a cable with HDMI and phono donnectors don't buy it or plug it in!
HDMI is digital (Low Voltage Differential Signal at the hardware level) Phono is analog. Totally incompatible. Just because smeone in China makes it dies not mean it will work.

Cn you provide a photo of the labels by the 3 phono sockets on the back of the TV? or the full model number of the TV?
If the sockets are video (CVBS) and left right audio IN your old plyer will work with a simple phone to phono lead. Picture qulity will be poor though.
While I hate the waste, best to buy a new DVD player and ive the old one to charity (yes some do take electrical goods).

Robert G8RPI.

Thread: Another Scam
22/01/2022 10:57:52

This is a old one. It predates online market places like ebay. It used the prined autotrader and the like to identify marks.
They will end up "overpaying" you the transport agent fee and askig you to pay it in cash to the collection agent. Later the cheque is rejected by the bank and you are out the item and the cash fee.
A friend of mine had one on used car. it was identified early so police were involved nd it was worked through and resulted in prosecutions. They were even using stolen company cheques.

It's a bit differnent from the common bank details theft of today so maybe people are fallling for it again.

Robert G8RPI.

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