Running a 4 kW motor

[SimonH2]

This is what I'm struggling with - the idea that there were enough people with 133/230V supplies to make it worthwhile to build so many motors that it then became worthwhile to make 230V 3P inverters.

I think you are probably looking at this the wrong way round. Taking a step back ...

There are LOADS of 3P to 3P inverters/speed controllers for 415V in and 415V out - I've used/worked with/programmed a few. In that situation it's fairly easy to have a 6 diode rectifier to give you the around ±340V positive and negative DC busses (or a single 680V DC bus) needed for the inverter section to generate a 415V 3P output.

If you only have a 240V 1Ph supply then things are a bit different. It is possible to get the same + & - busses, but then each bus will only have single pulse charging which means a LOT of ripple. In theory adding huge smoothing caps could get round that - but then you would have a stupidly bad crest factor on the input current.
TL;DR version - it's really hard to make a 415V 3Ph output from a 240V 1Ph input at any sort of power without upsetting the neighbours and the DNO with the effect on the supply.

Ideally (I think) you'd aim for something like 207V 3Ph output as that would allow you to use a bridge rectifier on the input (and hence get 2 pulse rectification) - and I suspect that if you measured the output of most of these 1P-3P inverters/variable speed drives you'd find that's what they put out. Since there probably aren't a lot of 207V 3P motors around, 230V 3Ph is the next best thing - as long as you allow a bit of derating (which you need to do anyway when running at variable speed).

Then I remembered that I have the manual for dad's IMO Jaguar CDS drive, and it states : The CDS (0.75-2.2kW) range is rated for current output, therefore the actual power output depends on output voltage, which in turn depends on the supply voltage.


If you want higher output voltage then you either need a step-up converter on the DC bus which adds considerable expense, or a large and heavy transformer. So they make the drives they do because that's what's practical - and motors to run from them are available. I'm sure that if suitable motors were rare (which usually means expensive) then there'd be demand for drives with 240V 1P input and 415V 3P output - though much less demand due to the extra expense.

 

[ban-all-sheds]

None of that explains anything other than a mutually-supportive environment of 3-phase converters with a P-P voltage of 230V, and motors made to match.

And it still does not address my struggle about how many people, and where, could take a 3-phase motor designed for a P-P voltage of 230 and successfully connect it to a public 3-phase supply.

 

[ban-all-sheds]

I think you are probably looking at this the wrong way round.

The way round I am looking at it is that motor makers make motors which are designed to be powered by the 3-phase supply delivered by the electricity generators/distributors in the geography where they sell the motors, and that for users who have not contracted to receive a 3-phase supply there are devices available to create a 3-phase supply for them using a single-phase input.

 

[Notch7]

I dont know much about electrics, but I do know electric 3 phase motors on woodworking machines are often dual voltage.

I believe that single 415v 3 phase can sometimes be converted to 240v 3 phase by internal modification.

Hobbyists often use such machines in their home workshop using a static converter.

 

[SimonH2]

And it still does not address my struggle about how many people, and where, could take a 3-phase motor designed for a P-P voltage of 230 and successfully connect it to a public 3-phase supply.

Leaving aside that 230 P-P isn't correct, you still seem to be missing the fundamental issue that a 3 phase motor can (as long as all the connections are made available) be wired to run at two different voltages one of which is 1.7 (√3) times the other.

So, take a motor that's 240V wired Delta, re-connect it in star, what's it's operating voltage now ?
What's the standard supply voltage for 3Ph in this country (and many others) ?

When a manufacturer designs a motor, they'll have a number of competing optimisations to consider. One is whether to make it 415V delta so it's easy to use a star-delta starter DOL to a 415V 3Ph supply, or make it 240V delta which makes it easy to use DOL to a 415V 3Ph supply or on a 1Ph input converter. The choice also affects a number of design parameters - the most obvious being the choice between fewer thicker turns for the lower voltage option vs more thinner turns for the higher voltage option. For a small low power motor, there a consideration there in terms of ease of winding and robustness of the windings where lots of turns of thin wire is less desirable.

Given that there's a distinct gap between the small motors that are practical to run of a 240V 1Ph supply, and the very much larger ones that could only be run on a 415V 3Ph supply and might want a star-delta starter, there really isn't any conflict there. Making a small motor ? make it 240/415; making a big motor ? make it 415/700 (or 680 or whatever).

Hopefully you'll now realise why there's no problem.

 

[ban-all-sheds]

Leaving aside that 230 P-P isn't correct

So when a 3-phase supply is described as "X volts", isn't X the phase to phase voltage?

you still seem to be missing the fundamental issue that a 3 phase motor can (as long as all the connections are made available) be wired to run at two different voltages one of which is 1.7 (√3) times the other.

No, I'm not.

Because the fundamental issue which has been concerning me is the supply. Yes, if you connect it star then the voltage across each winding is indeed 230V not 400V. But see my question above - what is the phase to phase voltage of the 3-phase supply used for the motor?

What's the standard supply voltage for 3Ph in this country (and many others) ?

400V.

or make it 240V delta which makes it easy to use DOL to a 415V 3Ph supply or on a 1Ph input converter.

If a supply is described as 240V delta does that not mean a single-phase voltage of 139V?

Hopefully you'll now realise why there's no problem.

The only "problem" which has concerned me is not how motors are wired, it is how there can be something called "230V 3-phase" for which motors are made. Unless, as I said, what's evolved is a mutually-supportive environment of 3-phase converters with a P-P voltage of 230V, and motors made to match.

 

[SimonH2]

So when a 3-phase supply is described as "X volts", isn't X the phase to phase voltage?

Ah, I assumed you were using P-P as meaning peak-to-peak.

No, I'm not.

Actually, you go on to prove that you are still missing a fundamental concept.

Because the fundamental issue which has been concerning me is the supply. Yes, if you connect it star then the voltage across each winding is indeed 230V not 400V.

Eureka - now connect the dots ...
If each winding in a motor is designed for 230V then that motor can be used in delta on a 230V 3P supply, or in star on a 415V 3P supply as you go on to demonstrate :

But see my question above - what is the phase to phase voltage of the 3-phase supply used for the motor?

If a supply is described as 240V delta does that not mean a single-phase voltage of 139V?

NO, because a 3P supply is not STAR or DELTA, it is "just" THREE PHASE. It just has three line conductors providing sine wave voltages that are 120˚ apart - and may or may not have a neutral (some 3P systems are only 3 wires and no neutral). We'll ignore all those details as they aren't relevant - just concentrate on the 3 line connections.

Star and Delta have no meaning on the supply side - where they have meaning is in the connections for things like motors, transformers, and generators. But yes, if a supply is 240V 3P AND is a 4 wire supply with a neutral, then the neutral-phase voltage will be around 140V.

As an aside, I have worked on a true 220V 3P system. There was no neutral, 3P loads were just wired across the 3 phases, single phase loads were wired across 2 phases. This meant that all the single phase loads had two "hot" wires, and all the breakers were double pole. It was also a nominally a floating supply

The only "problem" which has concerned me is not how motors are wired, it is how there can be something called "230V 3-phase" for which motors are made. Unless, as I said, what's evolved is a mutually-supportive environment of 3-phase converters with a P-P voltage of 230V, and motors made to match.

That is down to you not understanding that a motor winding is made for a specific voltage - and it's the arrangement of connections of those windings that gives the required supply voltage for the motor. All 3 phase motors (at least of the sorts were talking about here) are inherently dual voltage - the voltage each winding is designed for (delta), and 1.7 times that (star).

Taking your diagram above. If the windings are each designed for 230V, then the star connected motor on the left will run just fine on a 415V 3P supply. If you try and connect it to the same supply connected in delta as on the right, then you'll be applying 415V to a winding designed for 230V - cue magnetic saturation, excessive currents, and if the motor doesn't have some suitable overload protection then it'll soon be an ex-motor, gone to meet it's maker, with burned out windings (if it hasn't set the place on fire first )
But, since the windings are 230V, you CAN use the delta connection on the right to run it from a 230V 3P supply - as commonly found from low power 1P -> 3P inverters/variable speed drives.

If the windings were each designed for 415V, then it would only run properly on a 415V 3P supply if connected in delta as on the right - 415V across each winding. If you tried to run it in star, then each winding will have only 240V across it - there's be much lower magnetic flux, much less torque, will run slower for a given load, and probably counter-intuitively run hotter
But where this is useful is in starting large (especially high-inertia) loads. If you connect the motor in star initially and apply power, it will start turning with reduced torque and most importantly with significantly lower current draw. When it's already turning, disconnect the supply, quickly reconnect the windings in delta, and re-connect the supply - it'll then run up to full speed. This is "star delta starting" and is often used on large loads to reduce initial current and/or mechanical stress. There are automatic and manual devices for doing this (I had to scrap a perfectly good manual one clearing out dad's garage) that don't involve fiddling with the wiring
It's not suitable for all types of loads as it relies on the load not presenting full torque during startup. So great for things like fans and centrifugal pumps, high inertia loads like rolling mills (that can be unloaded for starting). What it can't help with is things like positive displacement pumps which reach full torque more or less in the first revolution (or less) unless hydraulically unloaded.


If there has been any mutual development, I think it'll have been in only two areas :
1) Using 230V windings instead of 415V.
2) Making all the connections available.
Going back some time, all decent manufacturers brought out the 6 winding ends to 6 terminals. When the "budget" manufacturers got into the race to the bottom of the pond, one way of shaving a few pence off the price is to leave out 3 of the terminals and hardwire the arrangement of windings - giving a single voltage motor.
Since there's a lot of uses for driving 3P motors from 230/240V single phase supplies, there's a market for 230/240V 3P motors. Thus an incentive for a manufacturer to spend the extra few pence needed to make the motor dual voltage - it'll still ship as a "415V 3P motor", but by moving links in the terminal box a user can use that same motor as a "230/240V 3P motor".

 

[JohnW2]

Ah, I assumed you were using P-P as meaning peak-to-peak.

For what it's worth, so did I - since that's what (at least, in my experience) that abbreviation is usually used to mean.

Kind Regards, John

 

[ban-all-sheds]

I won't reply to all of your points.

I am not missing a fundamental concept - you are still missing what my fundamental question was about.

If you have a 230V 3-phase supply then you have 3 phases, 120° apart, each with a phase to neutral voltage of 133V. My question was, always was, and still is, where in the world is there a distribution network supplying 230V 3-phase to its customers?

If there are none, then why did people start making motors for such a supply? How motors are wired, and how they are connected is of no relevance. Either the supply is 230V 3-phase, i.e. 133V single phase, or it is not. Either a converter/inverter/whateverer takes a single-phase 230V supply and creates 3 x 133V waveforms 120° apart, and thus can be said to be creating 230V 3-phase, or it does not, in which case it cannot.

 

[SimonH2]

I am not missing a fundamental concept - you are still missing what my fundamental question was about.

No I'm not. I understand exactly what you are getting at - but there does NOT need to be such a supply ANYWHERE for there to be made motors which can run on it. As I said, a "415V 3P" motor may have 415V windings in delta - or it may have 240V windings in star. If the only requirement a motor manufacturer has is to make a "415V 3P motor" then the choice between those option will be down to whatever priorities the designer puts on the various parameters. However ...

If you have a 230V 3-phase supply then you have 3 phases, 120° apart

Yes

, each with a phase to neutral voltage of 133V.

Not necessarily - there are 3P systems without a neutral. You have to relax and open your mind, and understand that not all electrical systems look just like the ones you are used to dealing with - clearly all 4 wire with a neutral since you continue to fail to grasp the concept.

My question was, always was, and still is, where in the world is there a distribution network supplying 230V 3-phase to its customers?

As I mentioned, I have in fact worked with one if you look at the "As an aside" para above.
This particular installation was on a ship (and 60Hz), with all 3P loads having to be 220V (or thereabouts). There was no neutral ANYWHERE in this system - all single phase circuits were wired across two phases meaning that there were two "lives" in a similar way to 110V site supplies.
I recall the Chief Electrician moaning about how careful they had to be in buying (especially portable) equipment to make sure it was really 3 wire and did NOT require a neutral - since a lot of people (including, it seems, equipment designers) seem to assume that one will always be present.
The system wasn't as built - back in the early 50s it was built as all DC. It was later updated by upgrading one of the DGs (Diesel Generators) to AC and connecting the previously DC circuits in the hotel load across two phases. 3 phase equipment was 220 (or 230 or 240, forget the detail now), and the single phase equipment was also 220V. The system was nominally floating, but had there been a neutral for reference, each line of a single phase circuit would have looked like a 130V (or whatever) waveform - and looked at together, there'd be 120˚ between them.
I have to assume it was a standard arrangement somewhere otherwise they'd have had to have custom equipment built to produce and use it.
Most of the big equipment stayed on DC - there's an awful lot of motors to make a ship of that age run, and some of them were "quite big", and of course the control systems (such as variable speed and reversible for cranes) would have had to be replaced had they converted everything to AC. Any new equipment was AC - even by the 80s and 90s it was getting hard to find DC equipment.
Sometime after I had any involvement they installed air conditioning, and to power it converted another DG to AC - which involved changing the camshaft and turbo disks to cope with the speed change needed (fixed speed diesels, highly optimised for that single speed).

I have to admit that I have not actually come across other systems like that - but then I don't generally work in environments where I would come across them. There are some "interesting" supplies used in a marine environment - but I can't talk about some of them.

How motors are wired, and how they are connected is of no relevance.

Err, it's very relevant. You are insisting that no-one would build a motor designed to run on 230V 3 phase unless there was 230V 3 phase supply commonly in use. I've pointed out than one of the options for building a 415V 3P motor will inherently create a motor that can be used on 230V 3P. If the motor isn't of a size where star-delta starting is ever likely to be a requirement, then the choice of winding voltage will be down to (among other things) whether it's easier to wind more turns of thin wire or fewer turns of thicker wire.

Either the supply is 230V 3-phase, i.e. 133V single phase, or it is not.

As above, you are still assuming 4 wire systems with a neutral. Leading on to ...

Either a converter/inverter/whateverer takes a single-phase 230V supply and creates 3 x 133V waveforms 120° apart, and thus can be said to be creating 230V 3-phase, or it does not, in which case it cannot.

Actually what they do produce is a 3 wire output, 230V 3 phase. There is, nowhere, any neutral - so nowhere will you find 133V single phases. Each of the 3 output phases would (if you synthesised a neutral*) like a 133V single phase, but there is no neutral, and so this is irrelevant.
Note - 3 phase input converters are different and it would in theory be possible to pass a neutral connection through them. The ones I worked with were all 3 wire (no neutral) since for these applications there is never any need for a neutral on the output.

* You could do this by connecting a motor or transformer wired in star to the converter and it would then give you a neutral. I suspect it would be somewhere around the DC bus midpoint (ie half way between + and - rails, probably not any physical presence) - and would be going up and down at the mains input frequency relative to the input neutral.

 

[SimonH2]

And a couple more points to consider :
APC make UPSs to work on 208 or 220V 3 phase
And I found this useful page giving a list of supplies to be found around the world. There's some interesting ones in there, such as the Bahamas. Looking at Costa Rica (110/208), and given that it's using 60Hz, I can't help wondering if the USA has had something around the 120/230 mark as a standard supply in the past ?

 

[ban-all-sheds]

there does NOT need to be such a supply ANYWHERE for there to be made motors which can run on it.

Well, theoretically that is true.

But when practicalities are introduced, I struggle to understand what would be the commercial viability of motors made for which no customer could obtain a supply.

So, back to square 1 - why were motors made which would work off a 230V 3-phase supply (no matter how they were wired) if there were no 230V 3-phase supplies available?

Not necessarily - there are 3P systems without a neutral.

Indeed there are.

And how many of them feature a phase to- phase voltage of 230V?

You have to relax and open your mind, and understand that not all electrical systems look just like the ones you are used to dealing with - clearly all 4 wire with a neutral since you continue to fail to grasp the concept.

It is not I who is failing to grasp the concept.

But it would seem that you are still failing to grasp the concept of "why would people make motors which needed a supply that was unobtainable?"

Err, it's very relevant. You are insisting that no-one would build a motor designed to run on 230V 3 phase unless there was 230V 3 phase supply commonly in use. I've pointed out than one of the options for building a 415V 3P motor will inherently create a motor that can be used on 230V 3P.

i.e. inherently create a motor which can be used on a supply with 3 phases having a phase to phase voltage of 230V.

As above, you are still assuming 4 wire systems with a neutral.

No, I'm not. I am quite aware that a 3-phase system can work with no neutral.

Actually what they do produce is a 3 wire output, 230V 3 phase. There is, nowhere, any neutral - so nowhere will you find 133V single phases. Each of the 3 output phases would (if you synthesised a neutral*) like a 133V single phase, but there is no neutral, and so this is irrelevant.

OK.

The point of them, surely, is to allow 3-phase motors to be operated from a single-phase supply when a 3-phase supply is not available from the electricity supplier to the owner of the motor.

So he has a magic box which produces a 3 wire output, 230V 3 phase, i.e. a phase to phase voltage of 230.

If the owner of the motor didn't need the magic box because he did have a 3-phase supply available from the electricity supplier, would that supply have a phase to phase voltage of 230?

 

[ban-all-sheds]

Ah, I assumed you were using P-P as meaning peak-to-peak.

For what it's worth, so did I - since that's what (at least, in my experience) that abbreviation is usually used to mean.

Really?

Really?

Where had/has a 133/230V supply?

And several other posts mentioned 230/400V.

And several other posts (including ones from me) mentioned "230V 3-phase"

phase-to-phase voltage of 230V

There are LOADS of 3P to 3P inverters/speed controllers for 415V in and 415V out - I've used/worked with/programmed a few. In that situation it's fairly easy to have a 6 diode rectifier to give you the around ±340V positive and negative DC busses (or a single 680V DC bus) needed for the inverter section to generate a 415V 3P output.

i.e. using "P" as an abbreviation for "phase".

And yet despite all of that context, you two genuinely thought that I thought that "133/230" meant a peak-to-peak voltage of 230? And that I thought that "230/400" meant a peak-to-peak voltage of 400?

Really?

 

[SimonH2]

So, back to square 1 - why were motors made which would work off a 230V 3-phase supply (no matter how they were wired) if there were no 230V 3-phase supplies available?

You really do seem to have a comprehension problem here as it's been explained to you more than once.

Firstly, there are/have been 230V (or thereabouts) 3 phase supplies

Secondly, a 3 phase motor is inherently dual voltage. If you make a 415V one then it's going to be either 230/415 or 415/680 (or thereabouts) even if you don't market it as such - or even hide the capability by not bringing out the winding ends.

But it would seem that you are still failing to grasp the concept of "why would people make motors which needed a supply that was unobtainable?"

See above - such supplies are/have been available.

So far, your argument seems to be that you have never come across one and so cannot see that one might exist. From the sound of things you have worked with a larger selection of electrical supply systems than I have - but I HAVE works on a 220V 3 phase THREE WIRE system.

The point of them, surely, is to allow 3-phase motors to be operated from a single-phase supply when a 3-phase supply is not available from the electricity supplier to the owner of the motor.

So he has a magic box which produces a 3 wire output, 230V 3 phase, i.e. a phase to phase voltage of 230.

If the owner of the motor didn't need the magic box because he did have a 3-phase supply available from the electricity supplier, would that supply have a phase to phase voltage of 230?

That would depend on the nature of the supply. Just saying "X has a 230V single phase supply now, if he asks his supplier for a 3 phase supply he will get Z volts phase-phase" cannot be done without knowing the characteristics of the supply system to that customer.

IN THE UK, the answer would be that you'd get a 4 wire supply (with neutral) which you could use as a 415V 3 phase supply or as single phases of 240V, or any combination of single and three phase loads.
The answer elsewhere is "you need to know what the supplier offers" ! As I described previously, I have worked on a system where single phase loads get 220V on 2 wires, and three phase loads get 220V 3 phase on 3 wires. In some ways, it's a simpler system than a 4 wire one (one less conductor to start with) though it does require double pole breakers. And since the AC conversion was done specifically to allow "off the shelf" equipment to be used (the ship owner was based in the USA), I find it hard to imagine that what was installed didn't in some way reflect a practice which was current at the time in the USA.

After a little bit of searching I came across this thread which seem to suggest that the system was actually fairly common in Europe at one point, and still exists in some places.
In the page linked to in one post on that thread it seems clear that the USA did in fact have a 240V 3 wire 3 phase system. And somewhere down near the bottom it says : "Other special cases: There are also some special wiring used in some places. Another much rarer scheme is 230V between phases and no neutralin the supply (also called 230V delta). Houses are then fed two phase wires, neither of which is necessarily anywhere near earth potential. This is used in at least in Norway in some locations. Also in some places in Belgium three phase 220 across the phases (= 127 phase to earth/neutral, 230V Y output on transformer) is used on older domestic dwellings (new installations are 400/230V 3 phase, neutral, earth). For this reason all Belgian fuseboards (whether actual fuses orcircuit breakers) protect both current carrying wires irrespective of supply type."

So the simple answer is that the motor manufacturer make such motors because there are such supplies around - which should end the discussion.

 

[ban-all-sheds]

You really do seem to have a comprehension problem here as it's been explained to you more than once.

What's been explained to me more than once is how motors can be made to work on any voltage you like, and/or wired to work on different voltages.

None of which was an answer to my original question:

Where in the world do they have 230V 3-phase supplies, such that there would be motors made for it?​

Firstly, there are/have been 230V (or thereabouts) 3 phase supplies

Jolly good.

Just think how many pointless posts explaining things of no relevance could have been avoided if my question "Where in the world do they have 230V 3-phase supplies, such that there would be motors made for it?" had been answered.

Firstly, there are/have been 230V (or thereabouts) 3 phase supplies

Jolly good.

Where are they, and how large a market for 230V 3-phase motors is there in those places?

Firstly, there are/have been 230V (or thereabouts) 3 phase supplies

How long ago? And at the time, whereabouts, and ditto re a market for motors?

Secondly, a 3 phase motor is inherently dual voltage. If you make a 415V one then it's going to be either 230/415 or 415/680 (or thereabouts) even if you don't market it as such - or even hide the capability by not bringing out the winding ends.

And that would be 230V 3-phase, i.e. a phase-to-phase voltage of 230?

So far, your argument seems to be that you have never come across one and so cannot see that one might exist.

No, my question was "Where in the world do they have 230V 3-phase supplies, such that there would be motors made for it?", which I asked because I had never come across one and so I was interested to know where they had them.

I HAVE works on a 220V 3 phase THREE WIRE system.

Jolly good.

Just think how many pointless posts explaining things of no relevance you could have avoided making if you had decided to answer my question "Where in the world do they have 230V 3-phase supplies, such that there would be motors made for it?" instead of making posts explaining things which did not answer it.

I HAVE works on a 220V 3 phase THREE WIRE system.

Where?

That would depend on the nature of the supply.

Indeed it would.

Just saying "X has a 230V single phase supply now, if he asks his supplier for a 3 phase supply he will get Z volts phase-phase" cannot be done without knowing the characteristics of the supply system to that customer.

Fair enough.

So where in the world, when a customer asks his supplier for a 3-phase supply, will he get 230V phase-to-phase?

IN THE UK, the answer would be that you'd get a 4 wire supply (with neutral) which you could use as a 415V 3 phase supply or as single phases of 240V, or any combination of single and three phase loads.

Jolly good. (Even if a little out of date now).

But you would not get a 230V (or 240V) 3-phase supply, would you.

The answer elsewhere is "you need to know what the supplier offers"

Indeed it is. And since the suggestion was that there are suppliers who offer 230V 3-phase, and that was not a system I remembered ever encountering, I asked the question "Where in the world do they have 230V 3-phase supplies?"

As I described previously, I have worked on a system where single phase loads get 220V on 2 wires, and three phase loads get 220V 3 phase on 3 wires.

You did.

This is 220V 3-phase - what do you connect between to get 220V single-phase?

In some ways, it's a simpler system than a 4 wire one (one less conductor to start with) though it does require double pole breakers. And since the AC conversion was done specifically to allow "off the shelf" equipment to be used (the ship owner was based in the USA), I find it hard to imagine that what was installed didn't in some way reflect a practice which was current at the time in the USA.

A 3-phase supply, 230V phase-to-phase, was not something I had ever known used in the USA, hence my question "Where in the world do they have 230V 3-phase supplies?".

After a little bit of searching I came across this thread which seem to suggest that the system was actually fairly common in Europe at one point, and still exists in some places.
In the page linked to in one post on that thread it seems clear that the USA did in fact have a 240V 3 wire 3 phase system. And somewhere down near the bottom it says : "Other special cases: There are also some special wiring used in some places. Another much rarer scheme is 230V between phases and no neutralin the supply (also called 230V delta). Houses are then fed two phase wires, neither of which is necessarily anywhere near earth potential. This is used in at least in Norway in some locations. Also in some places in Belgium three phase 220 across the phases (= 127 phase to earth/neutral, 230V Y output on transformer) is used on older domestic dwellings (new installations are 400/230V 3 phase, neutral, earth). For this reason all Belgian fuseboards (whether actual fuses orcircuit breakers) protect both current carrying wires irrespective of supply type."

Was common... still exists in some places... much rarer scheme... some places in older houses in Belgium....

None of that, to me, indicates that there would be enough people living in these places who could use a motor designed for 230V 3-phase for it to make commercial sense for manufacturers to produce them.

Hence my question "Where in the world do they have 230V 3-phase supplies, such that there would be motors made for it?"

So the simple answer is that the motor manufacturer make such motors because there are such supplies around - which should end the discussion.

I cannot dispute that there are such supplies around because I do not have an exhaustive knowledge of all the supplies there are in the world. I can say that I'm not aware of any, and therefore ask the question

Where in the world do they have 230V 3-phase supplies, such that there would be motors made for it?​

But nobody has managed to answer it yet.