Meddings MF4 drill electrics

Well, I am not going to try to compete with John on word count, especially as he appears to have quoted most of the technical manual for us

Bottom line is I will not be fitting any contactors or NVRs but I will be fitted the EMC filter as that is required to meet EN standards on this inverter. Plus I have it and it was very little extra cost so it would be silly not to.....

Oh, and sorry Muzzer, ignore my last question, I didn't realise you had linked to the filter data sheet in your post.

ok, next quick installment. changing the motor to delta configuration.

It is a Brook Compton and the wiring info is on the terminal access cover......

So this is the original wiring in star configuration......

and this is it changed to delta (or mesh as it is called on the label)....

I noticed a few things when doing this.

First the incoming cable appears to be screened SY cable but the screen is not connected either end. Not a great problem, there is at least an earth, but silly not to do it properly.

Second, I haven't measured it but to my eyes the SY cable looks to be 0.5mm2. If it is, that would be ok in star wiring (1.7A FLA) but a bit marginal in delta (3A FLA). I need to check it properly but I might end up replacing it.

Lastly, you can see crimp terminals were used, trouble is the washers on the terminal posts were not in the right order. So it went backnut-washer-washer-crimp-nut rather than backnut-washer-crimp-washer-nut. Consequently the crimps were firmly stuck to the back of the nuts and I bent them undoing the nuts.

None of this a big deal but it does make me wonder about the competence of who wired up the motor!

Inverters come up regularly as items of confusion or requiring questions answered. I thought I would take a couple of pictures of the installation on my milling machines, they are both done the same with both all motors (Horizontal, vertical and feed) running on inverters. They are all wired with a line filter on the input supply and a load reactor (choke) on the output. They are all stuck on the wall high up and out the way so they get a good air flow. Wiring is all done properly (IE. as required in the instructions)using 24 volt signals etc.

Mark

Mark, that is a very neat installation. I am also jealous of the clean white walls and double glazed window. A world away from my garage!

On my boxford I put the inverter in an enclosure on the wall, you can just see it in the background (top left) in this picture.

On the drill though I fancy making it "self contained". ie the inverter mounted on the drill. Given this inverter is pretty compact I reckon I can put it on the left hand side where the e-stop used to be.

To this end I have spent a few hours learning sketchup and modelling what it might look like. This is the result so far:

It has a fan on top as there will be little airflow in the enclosure and the fan will have a dust filter to stop swarf etc falling through! The square block on the lower front diagonal is another fan dust filter used as an air inlet filter.

The emc filter is external on the back but there will be a cover over the top to protect the mains in terminals.

This will probably change as I build it but it was fun modelling it

First job though is to lash up the inverter on a bit of ply to check everything works!

Edited By Toby on 15/01/2017 09:52:02

One thing I haven't worked out yet with this design is how to easily make and fasten a window on the front. ideally it will be openable so I can get to the inverter buttons.

I listen to DAB radio through an ipod linked to a stereo in my workshop.......took a while to figure out why it kept turning itself off when I used the lathe or mill, then I twigged both are running from inverters........

Guess I need to invest in an EMC Filter

Nice work with the SketchUp model, Toby

First thought for your 'window' was to insert magnets ... but swarf & cast iron dust may be a problem.

... I would probably just let it slide in a couple of grooves [a bit like a portcullis]

MichaelG.

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https://en.m.wikipedia.org/wiki/Portcullis

Edited By Michael Gilligan on 15/01/2017 10:26:15

It does sound like typical EM interference. It's funny you should mention that because I've got a radio that keeps turning on, rather than off, whenever my neighbour puts the central heating on.

Michael W

I can see why Toby wants this pillar drill so badly, because it's a very nice example, you only have to look at the quality of the drilling table to know it's a good one and you'd struggle to get something just as good brand new without spending a huge amount of money on it.

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... Having recently had that PaceMaker implanted ...

I need to investigate this quite carefully !!

MichaelG.

MichaelG: Thanks, I think you are right, magnets and swarf will become a problem. I did think of velcro but that might have similar problems. I like the idea of the portcullis but wasn't sure how to easily stop it dropping on my fingers.

Anyway, after a bit more playing I have come up with this:

So it will lift up and rotate over the top, resting upside down on top of the fan. I need to double check my pivot points and arm lengths etc but I think it is roughly right as shown.

Michael W: Yes, so far it looks like a good one. It is certainly better cosmetically than anything else I have seen 2nd hand and way more solid than anything new in my price range.(ie up to £500). The real test will be when I get it running though......

Thanks for the compliment on my installation, there are a number of shortcomings in it but it is OK for my own purposes (it would not be acceptable for an industrial application).

I know you are only using the line in filter but I thought I would put the picture up to show what is needed for a fully filtered setup. The two large filters are the drive side chokes (drive reactors). They take out all the horrible digital synthesised waveform and turn it into a close approximation to a sine wave. I imagine that my installation would be significantly safer for Michael than an unfiltered arrangement! There are a lot of armature electronic engineers on here (and a few professionals I suspect from reading some posts), any of them with access to a oscilloscope can see for them self what the output looks like without a choke and then they can see the improvement if they buy one.

You might also notice I am using the cheap Hungyang inverters - I like them!

Mark

What are Huanyang inverters like on the range they will cover Mark. In other words min power on an inverter of a given rating?

I went for Mitsubishi as I have had it for a long time and it was early days for chinese inverters. People seemed to be happy with the cheapest they could lay their hands on not long after a changed my lathe over.

Also thought they would produce a decent manual. Worth while for if there are problems. Mine wasn't expensive. It was slightly used. Not an uncommon problem. Motor not up to what turned out to be needed so both changed. I took care of that by doubling it on my M10. x2 as they fitted lower power motor to the ME's. I didn't 'alf have some problems getting it to fit.

John

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If the vfd control panel is very close to the cut out (or in line with it) then a soft clear plastic cover should do the job. Something like the flexible plastic on a see through umbrella, or fold up map cover etc.

Steve

Mark: You are right about the noise generated on the motor side. When measuring phase voltage and noise on the system we are currently developing I need to put the signals through an R-C filter just to make something meaningful from them.

Just to give people an idea how things work, this is a trace I took of the pwm switching signals to the output transistors on a VFD. If you squint you might just work out there is a sine wave in there somewhere

put through an RC filter you something more meaningful......

Steve: I like the soft plastic idea although it might challenge my metal bending skills trying to get the panel close enough to the front of the VFD

Interesting......never realised it might be beneficial to filter the output of the VFD's

Are the chokes commercially available items Mark ?

Toby, the my output is better than that after a choke (I realise you are measuring the transistor drive voltage so it may well be different). I don't have any traces from the scope but the biggest error I saw was the shape of the wave (it was a little "stepped" and there was some offset or dwell at zero crossing).

Alan, I get them from Lamond Automation, I have not been able to get them cheaper anywhere else. The make is not important, you just need the correct amperage. These are recommended when using a non-inverter duty motor (as in the motors on our machines) and the justification is that the choke removes the damaging transients that might cause insulation breakdown on older windings and probably helps with the issue of arcing across bearings - not that I have ever seen that but I have been assured it can happen. There does seem to be an improvement in audible noise but that may be imagination.

Using soft plastic to cover the inverter panel might be OK if there are no hot chips flying about but in my workshop it would be ruined in no time!

Mark

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Looks good to me, Toby

MichaelG.

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Thanks, Mark

... It does seem that I need to take this quite seriously.

Chatting to the PaceMaker Nurse, when she checked the settings on 05-Jan, she was quite emphatic that I shouldn't use the Induction Hobs ... apparently, now that my Heart is under PaceMaker control, that magical 33bpm that my ventricles had 'on standby' has probably been lost.

Perhaps I could get 3-phase power to the workshop, on prescription

MichaelG.

You might want to stay out of our kitchen Michael, the hob draws 10 kW at full tilt... I don't know how far away from it you would need to be but I expect safe distance might be outside the house!

Mark