Digi Phase Converters, 3 phase motors etc, Anyone?

i won’t get 380v letween L1 and L2 etc because this is a 220v output drive, designed to give 220v in delta.

Have you measured it ?

If you have single phase input voltage of 220v ac to an inverter that can give you a 3 phase output then each pahse will be 220v output per phase, however if you then measure across 2 or more phases you will read 380v.

Hopefully this link will explain it a lot better than I can.

http://home.comcast.net/~zenkai-audio/gndtss/pages/s1_3ph.htm

On the link I have posted they have used standard US voltages however you can plainly see the relationship between single and 3 phase being a constant.

FWIW All that I am trying to explain to you is that the reason for the 2 voltages on the motor plate is due to the phase (single) and phase to phase (three) voltages for which the motor has been designed.

If you do have 220v across two phases, check across 1 phase to neutral you should read 127v (220 / root 3 = 127)

If that is the case you will have undervolts on your motor ! and as your motor is designed for 220/380 it will not perform correctly

Your motor windings can be configured via the motor terminals for star or delta depending upon the load or torque required for the application.

I give up now. Not sure if cheeky is a troll or just an idiot given he only uses selective quoting, but I still think he should connect a 230/400v motor in delta to UK 3 phase (or even via a star delta starter) and prove that we’re the clueless idiots.

Why resort to ad hom ?

Oh and please explain the star phase 😆

Just for you Cheeky, when using the term star phase, what I meant was the time period during which a star delta starter, is running the motor in a star configuration.

Perhaps Star running period would of been a better term.

nope cheeky i haven’t measured it, but i will.
trying to stay open minded and learn something.

but i btw i can’t measure accross phase to neutral in delta cos there’s no neutral, right?

but i btw i can’t measure accross phase to neutral in delta cos there’s no neutral, right?

The only place I suggest you measure is at the output terminals of the inverter, the reason I have suggested you do this is so that you will see the difference between phase to neutral and phase to phase, hopefully this will clarify things.

All this talk of phases takes me back, all we need now is a few R Y B’s and we’re back in the real world!
This is of course one advantage to the name ‘line’

so when measuring between phase and neutral at the output terminals, you suggest i measure from one output phase terminal, to the supply neutral?
when the output terminals are connected to the motor wired in delta, there’s no terminal serving as neutral, right?

so when measuring between phase and neutral at the output terminals, you suggest i measure from one output phase terminal, to the supply neutral?

That will be fine, remember AC volts on your meter

when the output terminals are connected to the motor wired in delta, there’s no terminal serving as neutral, right?

Correct !

Be careful you will have 380v across them terminals !!!

nope!

supply coming in at 230v. motor was not driving anything, just spinning with no belts on the drive pulley.

with a digital multimeter:

1st phase 225-230
2nd phase 240 ish
3rd phase 280v ish

any phase to neutral 130 ish

dvatmark did say somewhere back at the start:

Its worth noting that a digital volt meter wont read correctly as the voltage waveform will not be sinusoidal. If you want to measure the true output voltage you’ll need a oscilloscope I’m afraid.

for what it’s worth cheeky. the plate in the inverter reads
“output: 3ph 220v 7A 50hz”
given it’s wired up to the delta configed motor, designed to run on 3ph 220v in delta, i can’t see where 380v comes into it.
the point is there is no neutral being used anywhere but in the supply to the drive. between the drive and the motor, there’s just 3 lines of 220v (ish) being wired accross 3 windings at 220v. why are you trying to see 380v somewhere?

if it was in star and running on 380v 3phase supply, as it was at my neighbour’s house, we would of course see 220v from phase to neutral used accross each winding, as you say.

and thanks for the extra bit of patronising. remember AC volts on your meter. come on.

they all seem to creep up if i leave the voltmeter there. sure someone can explain that?

seems not that balanced accross the phases, normal-ish for running through an inverter from what i’ve read, but i’da thought with a digital drive they might get it more balanced than that?

I would expect it to be a bit better balanced, but remember that that inverter is not exactly a pinnacle of engineering, so as long as things run as expected I wouldn’t be too worried.
Probably worth double checking all the wiring connections are tight, and the wiring looks ok, just in case something isn’t quite right, as bit extra resistance could cause a leg to run high/low.

You could also try swapping the probes around and see if you get the same reading between each terminal, as it could be the way the multimeter is reading the voltages (shouldn’t make any difference on a good quality meter, but cheap ones can have such quirks).

As for your previous post about having to increase boost, you might want to read this guide on setting it correctly – https://www.inverterdrive.com/HowTo/Maximum-Torque-at-Low-Speed-from-a-Simple-Inverter/

thanks mc

all quiet on the cheekyboy front?

1st phase 225-230
2nd phase 240 ish
3rd phase 280v ish

any phase to neutral 130 ish

From my previous post

If you do have 220v across two phases, check across 1 phase to neutral you should read 127v (220 / root 3 = 127)

So it appears thatyour motor is running on a reduced voltage from its design voltage.

If you had 220v per phase, ie phase to neutral you would have 380v across phases (as long as the phases are correct ie 120 degrees apart)

Your inverter is receiving 230 in from your mains, this id then converted to a 3 phase output, your voltage output appears to be set up for 220v across phases, is this adjustable can you take it up higher ?

Your motor is designed for 380v in delta, whereas you only have 222/240/280 across phases, the fact that there is such a large disparity on your third reading indicates an issue somewhere with the settings on the output voltages

all quiet on the cheekyboy front?

My bike cannot ride itself 😉

good, thought you must be out riding!
i was glued to the TdF…
but yep, i’m in agreement about phase to neutral voltage obviously, that’s what i meant to imply.

but i have to just disagree that my “motor is running on a reduced voltage from its design voltage” and ” motor is designed for 380v in delta”

it’s designd to run on 220v in delta and 380v in star.that’s what a dual voltage motor means in this case. and i’m not arguing about that anymore!!!
so there!!! 🙂

but i have to just disagree that my “motor is running on a reduced voltage from its design voltage” and ” motor is designed for 380v in delta”

it’s designd to run on 220v in delta and 380v in star.that’s what a dual voltage motor means in this case. and i’m not arguing about that anymore!!!
so there!!!

OK fair enough ! one last parting bit of advice, as you are running at a reduced voltage (130/240) you will pull more current just make sure your input cables are man enough for the job and you have adequate protection at your distribution board/consumer unit, Good luck 😉

aye no worries there. currnet is as it should be (i think), showing between 2 and 5 amps depending what i’m asking of it, and all via it’s own 16amp RCD with nice big cables.

Jamie… it all sounds fine, and unless your inverter has some good filtering on it your voltmeter won’t be too happy measuring PWM, so is probably why you get differing results.

Cheeky… can’t you just accept that some people on here might actually know more about this than you?

Cheeky… can’t you just accept that some people on here might actually know more about this than you?

Can you actually point to a statement or anything that I have said that is wrong. all that I tried to point out to Jamie initially was the fact that his motor plate said 220/380V was because 220 is line voltage and 380 is line-line voltage, if you actually knew anything about motors you would know this, the gibberish you have spouted above is pure comedy. 😉

no, you’re wrong!

i’m just being a wind-up merchant, but still, you’re wrong!

i think it might be time for some CVs from the respective contributors.
i know one’s, and i was very inclined to listen to him as a result, but he’s gone quiet, probably wisely. so, come-on, cheekyboy, funkynick, mc, therapy69 et al. what makes you so qualified? (tho i obviously agree with some of you, and not others…)
except me cos i know shit-all apart from what i’ve learned on this thread, very informative thanks, and what dual-voltage motors are, in this sense anyway 😀

Lucky I don’t do the electro-magnetics for designing motors then… oh ooops!

As I said, some people might actually know more about this than you!

Now, while you are quite correct that for a 380V 3-phase supply, the phase to neutral voltage is 220, but why would the phase-neutral voltage need to be stated on a 3-phase motor when there is no neutral connection? The phase-neutral voltage is implicit by the fact it is 3-phase.

Secondly, if what you believe is true, why would there be two sets of currents listed on the motor, but only one power? Are the two currents related to the two possible configurations which the motor can be run in, then how? Also, what is the rated voltage for the machine in delta? What about in star?

What makes me qualified?

I design the things… design the inverters… got a PhD…

But obviously I am talking gibberish… ;o)

good good, thanks nick. just what i was trying to say too

why would the phase-neutral voltage need to be stated on a 3-phase motor when there is no neutral connection? The phase-neutral voltage is implicit by the fact it is 3-phase.

Well its stated because that is what the phase voltage is ! its on the motor plate because that is the voltage the motor was designed to operate on.

I have never stated that there is a neutral connection on a 3 phase motor, the only reason I have mentioned neutral is for the purpose of explaining the voltage measured on a single phase

In star you have two phases over two windings, in delta you have two phases on each winding.

Secondly, if what you believe is true, why would there be two sets of currents listed on the motor, but only one power? Are the two currents related to the two possible configurations which the motor can be run in, then how? Also, what is the rated voltage for the machine in delta? What about in star?

Oh come on Nick! simple power calcs here

P=IV

In star 220volts x 5.9 Amps = 1298w

In delta 380 x 3.4 Amps = 1292w

Obviously Ive omitted the Pf but as a designer Im sure you will agree the maths never lies.

I`m just a lowly projects engineer supervising generator installations, cut my teeth on commissioning but too old for the long days and late nights nowadays 😉

I know about this because I’ve played with and wired up various bits of machinery. I certainly never claim to be an expert on the theory behind how the motors work, but I certainly know how they should be wired and at what voltage.

I’ve got one inverter running of single phase in the garage that runs a 3 phase motor wired delta for 230V 3 phase powering a two post lift, which quite happily lifts it’s rated capacity.
Initially built a rotary phase converter that ran directly of 230V single phase for powering an old tyre machine, which I had to change the motor on to 230V delta to do so.
I then bought a milling machine, which had one motor that couldn’t be swapped to 230V, so I upgraded the rotary converter by adding a 230 to 380V step-up transformer so it produced 380V 3 phase, and swapped the tyre machine motor back to star to run on the higher voltage.
Since then I’ve added a CNC lathe that uses the 380V 3 phase to power the main spindle motor VFD.
And I’ve also got a big CNC mill that will be getting run in a similar way once I get around to doing a retrofit to that. The motor is rated for 380V delta (it’s fixed internally – I had it apart in the hope it was in star, but the coil ends are in a delta connection), so my initial plan prior to getting the lathe had been to run it via a 230V inverter, and live with the reduced torque/power above 29Hz as per this guide – https://www.inverterdrive.com/HowTo/240V-Supply-to-a-400V-AC-Motor/ , but since the lathe runs happy the way it is, I’ll run the mill the same. It does however mean I’ve got a 2.2kw inverter spare, but I also have a big manual lathe to get into the workshop at some point…

So yeah, I know **** all about 3 phase, inverters, and induction motors.

fair play mc, what do you use it all for? what do you make?

Quite a wide ranging mix of stuff.

2 post ramp is for vehicle repairs, tyre machine is just because I got it for taking it away, CNC lathe is mostly for producing a bike tool, the manual mill is for a second op of the bike tool as well as for doing repairs, the big CNC mill is more of a long term project which I picked up cheap but will be handy for dealing with big lumps of steel, and the big lathe I’m still trying to figure out how to fit in the workshop.

However that’s only the 3 phase stuff. I’ve also got a small CNC mill which is one of my current projects to upgrade for some production work, a little CMM/Probing machine, a bench top injection moulder, and another single phase lathe. Then there’s a big MIG welder, a little TIG welder, a 3in1 metalworker and lots of other smaller tools.

As for what it all gets used for, last completed project was a complete strip/rebuild on a Howard 300 rotovator. I’m currently building a metal stand with drawers for the CNC lathe so I can get it moved from the middle of the workshop floor. Then I can get my kindling wood processor back in to finish making guards for it and add an extra hydraulic valve and switch to. And on the drawing board I’m trying to re-create a variable speed pulley for a vintage combine from photos and parts diagrams. The pulley is obsolete and all efforts at finding one to copy have so far failed, despite being fitted to various combines over a period of ~15 years, and I suspect in order to get the stated speed range, they’ve used non-standard V-belt angles :-/

So as I said, quite a wide range of stuff.

funkynick
What makes me qualified?

I design the things… design the inverters… got a PhD…

But obviously I am talking gibberish.

I don’t suppose you have anything lying around that would get my spindle motor running?

Cheeky…

But it’s a 3-phase motor, as I said the phase-neutral voltage is exactly defined as 220V by stating it is a 380V 3-phase motor, no further information is required.

Anyway, lets have a look at your calcs:

Oh come on Nick! simple power calcs here

P=IV

In star 220volts x 5.9 Amps = 1298w

In delta 380 x 3.4 Amps = 1292w

Obviously Ive omitted the Pf but as a designer Im sure you will agree the maths never lies.

For a star wound motor:

Electrical power = number of phases * phase-neutral voltage * phase current * power factor

So, from your interpretation we have:

Number of phases = 3
phase-neutral voltage = 220V
phase current = 5.9A
power factor = 0.85

That gives:

Electrical power = 3 * 220 * 5.9 * 0.85 = 3309W -> somewhat larger than the 1.5kW output power stated on the name plate.

Okay, how about for the delta wound motor:

Electrical power = number of phases * phase-neutral voltage * phase current * power factor

Again, from your interpretation we have:

Number of phases = 3
phase-phase voltage = 380V -> phase-neutral voltage = 380/sqrt(3)
phase current = 3.4A
power factor = 0.85

Which gives:

Electrical power = 3 * (380/sqrt(3)) * 3.4 * 0.85 = 1902W -> this is closer to the 1.5kW, but doesn’t match the value given for your configuration above.

As there is only one output power listed on the name plate, these two should be pretty much identical!

Another way of looking at your configurations would be to consider the notional motor impedances, where you consider the motor at full power to be a static load.

If you think about how a star wound motor is configured, there is more impedance between any two phases than there is in a delta wound motor, there has to be as the windings are essentially configured in serial for a star, and parallel for a delta. With the two configs you listed, you have a higher current for the star wound machine than for the delta. How is this possible if the star wound machine has a higher impedance?

However, this all works quitely nicely if you swap your star and delta machine configs… so the delta runs at 220V and the star runs at 380V…

What was it you said? The maths never lies? 😉

integerspin…

Unfortunately we build very specialist motors and inverters, designed for individual customers… nothing off the shelf and nothing really less than a few hundred kW.

Sorry about that… but it looks like a higher power unit similar to the one which Jamie bought, which started off this whole thread, would do the business.

Integerspin, what kind of machine is that on?

And are you looking to buy new or find something suitable second hand?

New secondhand, who cares, as long as I can run it.
It’s on a 1985 Matsuura milling machine. No gears the spindle ran
from 0-8,000 rpm on an inverter[an inverter the size of a fridge], but I stripped the original[all working] electronics and binned it all as the machine was so big I couldn’t squeeze it in my garage. I haven’t yet refitted the electronics, I have done part of it and may well finish it this year.

I knew it was something big, and was about to say a big wood router, but they normally use modified AC motors with direct mounted tooling. Metalworking usually involves a belt as the spindles are too big for direct mount.

I hope you’ve got a good power supply 🙂

Going by the motor voltage, I’d say it’s designed to run of a 230V 3 phase inverter (similar voltage rated servos run of 230V single phase drives).
Personally, I’d try the guys at https://www.inverterdrive.com/ as inverters are their thing. I’ve not personally used them, but seen them recommended a few times on various forums.
Other option would be to try Gary at Zapp Automation, as he’s knows his stuff, and if he can’t supply I’m sure he’ll be able to point you in the right direction.

Cheeky, you are wrong, but if you want total proof of this and your ramblings go and connect a 380VAC supply to a delta wired motor rated at 220VAC and tell us what happens, just stand back from it when you turn it on, good luck.

And I would rather not say exactly what I do for a job but it involves a lot of 400V gear at 6300A.