[Closed] Digi Phase Converters, 3 phase motors etc, Anyone?

Could be wrong, but line to line voltage (ie between phases) should be higher than line neutral? But probably depends what you're measuring it with.

When im testing 415v 3phase, each leg to the winding is 220v to earth and between the windings is 415v, what have you got to earth from the motor terminal?

ah ok, i'll check some things.
it's wired in delta so there's no neutral

so at 220v 3 ph what should it be between phase and earth christian? any idea?

Line to line voltage is about 1.7 times the line to neutral voltage.

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.

Can you give me a link to the manual for the unit to have a look at?

When im testing 415v 3phase, each leg to the winding is 220v to earth and between the windings is 415v, what have you got to earth from the motor terminal?

415V 3ph = 240V ph-earth I hope
400V >> 230V and so on

square root of 3 being around 1.73 and all

220v three phase should show 220v between phases, as 415 shows 415 between phases, to earth probably 120v. dont work on 220v three phase myself but principle is the same. seems like the output to the motor is low as the unit is telling you which is why it has no torque, surpised its turning at all if thats the case mate!

Not quite, the 220v is line to neutral I.e. star connection so if you could measure the voltage across the outputs you should see 380v. But a mentioned above you can't do this without a scope (the output is a square wave, so a standard RMS algorithm like virtually all multimeters use doesnt work)

My initial guess is that the inverter is current limiting its output.

ok great, thanks a lot everyone.
yes i figured it was low volts to motor giving low torque.
still haven't checked voltages cos i'm lurgied up but will do with an needle type meter if that works

dvatcmark, it's this one :
http://www.ebay.co.uk/itm/251389853828
quite q lot of info there within the listing.
i notice it says "single phase connected to any 2 phases" under [i]How to install this VFD[/i]
i've got live and neutral of supply just to one terminal each at R-S-T in diagram. should i try bridging 2 together from live? guess i should.

You can have 220v phase to phase, not just 220v to neutral bud, equalling 380 to 415v, like i said not something ive worked on but does crop up!

Looks like a nice little unit. There isn't much you can wire wrong really, just connect the single phase input between any two of r s and t and the motor across u v w, the link the motor to be star or delta as required.

Don't get hooked up on the voltages, as its current and frequency that drives motors not volts.

As its giving an output and turning the motor its unlikely to be knackered, so I would put money on it being setup wrong.

The unit has a variable output either from an external input (variable resistor) or using the keypad. In the settings I'd check this first so that a) the output is set it to be by the keypad and b) the output is set it to 100% from the keypad Also check the max output frequency is set to 50hz .

Inverters usually ask for a motor size too to limit the current to a safe value to protect the motor. This might be set too low so check that too.

If the manual is chinglish this might take some time I'm afraid.

You can have 220v phase to phase, not just 220v to neutral bud, equalling 380 to 415v, like i said not something ive worked on but does crop up

220 to neutral is 380 line to line just like the spec says.

Vfd usually have a voltage vs frequency curve. You will only get the 220 v phase to phase at 50hz (or 60 hz in N.America) do you have it at full speed?

thanks dvatmark,
yep all that's checked and good. not getting hung up on volts, just that the voltage is the only setting that's wrong that's all. and aye, i don't have the supply phase connected accross 2 of RST so that should sort it.
and i know the motor's not knackered. it has to me my wiring or a setting, and seeing as i've sorted all the settings, it's user error, as usual.
right, might go off and change that wiring...

P.s. 220 v three phase exists I north America. At work we have installed a mchaine with 480 and 220 three phase systems

that's right, and this is a 380v in y wiring or22o in delta wiring 3phase motor, made for france. they did this so partly so they could sell to america withotu any parts changes

My email is in my profile if you need any more help

Looking at the ebay page it's definitely a 220V line-line output voltage and not a 415V, so do make sure that is the kind of motor that you have, otherwise you are going to be in trouble getting it to run at the full rated speed.

Now, talking of the motor, do you have the name plate ratings? And is there anywhere in the inverter settings pages where you can enter these values? Most importantly, the rated voltage and rated speed, and also likely to be the pole number of the motor if you want any idea of how fast you are actually trying to spin the motor!

My guess is that same as a couple of folks above, that the voltage/frequency settings are wrong, and so it's trying to run the motor with too little voltage for a given speed.

thanks nick and again dvatcmark.

as i said, the motor is dual voltage, ie it's designed to run ate 380v y-shape wiring, or 220v delta wiring. that's why the converter i bought is 220v 3ph out, to go with the delta option, right?

i have of course used the motor plate to get the relevant ratings and entered them in the inverter settings: max voltage, frequency, speed rpm etc. pole number i couldn't find, though am under the impression it's usually 4, and the inverter factory setting is 4

Sounds like you have wired it in star rather than delta.

Not sure if it is relevant but when I looked at a 3-phase saw my (electrician) son mentioned something about needing a 3-phase supply to the house - or the 'ability' to get 3-phase from the local electricity sub.

At this point I switched off and looked only at 240v :-), so it could be duff info.

nope it's definately wired delta twonks. and as far as i understand, in this case delta is for 220v, star, or'Y', is for 380v

just tried bridging the supply phase to the inverter over 2 of the RST terminals as described on ebay listing. made no difference whatsoever.

now i'm really stumped...

my next line of enquiry is setting 'intermediate frequency/voltage'
these values used to define start-up curve. from readin manual again it sounds like i may need to increase one or the other to get more torque as it's starting up. off to have a go...

right, so i can now get motor started while connected to the saw and runs up to speed, (though i must admit it seems very fast. rpm is set in inverter according to motor plate though)

i changed the intermediate voltage, ie the curve of the start-up (graph V against F) because in the manual it said wrong setting may result in under-torque of motor.

however it still seems lacking power/torque. and goes very fast as i said. i'd be worried about belts, and whole machine vibrates unsettlingly.

any more thoughts?

Jamie..

Can you post the name plate numbers? From those it should be possible to work out what pole number the machine is.

From what you are saying, it does sound like it could be a 2-pole machine, and not a 4 pole.

Before you start playing with the more advanced settings, go back over the basics.

Single phase should be across any two of the 3 input terminals. What ones doesn't matter, as they all go through rectifiers to provide a DC supply that is then used to generate the 3 phase. The inverter is only interested in seeing 280+VDC in it's capacitor bank.

What does the motor name plate state?
When wired in Delta, you should be using the higher of the two current ratings on the plate.

With the motor running, what frequency is shown on the drive? Provided it's saying 50Hz, the motor should be running at the correct speed (that's provided the motor plate is rated for 50Hz mains supply).
Also check to see how much current is being output (Hz, V and Current are all selectable for the display), and look to see what it maxs out at when you apply a bit load.

What's the motor driving ?

Sounds like you have the drive in the wrong mode, needs to be constant torque, it may be in V/F at the moment which will limit torque at low frequency (assuming you have a ramp accelerate program set in it)

Edit: Ignore all that, just read its a saw you are driving

Check and double check parameters !!

right, here we go

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mc, yes single phase is over 2 of RST. dc voltage reading 300 odd.
plate suggests 220v = delta and will draw 5.9A current.
according to inverter display it was drawing about this til it got up to speed, then went down to 2.9 or thereabouts

with motor running 50 Hz shown on drive

funkynick. any clues there if it's 2-pole or 4 pole?

thanks tragically1969. it's actually running a combinaton machine ie saw, spindle moulder, planer/thicknesser. quite a small one though.

anyone know what the cos and symbol spec is above the weight on plate?

Power factor.

Can you post a picture of the terminal box wiring ?

yes

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the bit of red on the black wire is just an old bit of sheathing or something.

and here's one of the box drive connections for good measure

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all looks right, right?

looking at the drawing on the Ebay page it may be a switched output, have you checked it is set up to output to voltage you require?

I'm looking at the KA,KB & FC, FA & FB switch set up.

looking at the drawing on the Ebay page it may be a switched output, have you checked it is set up to output to voltage you require?

I'm looking at the KA,KB & FC, FA & FB switch set up.

They are outputs for signalling.

Motor is wired delta for sure, just check that the pairs are to the correct terminals, the black wires coming from the windings should be marked.

right. think wiring is all correct, thanks tragic
now a new phenomenon
turning on machine with it's own switch trips out the inverter. starting it with it's switch already on, using the run and stop buttons on the inverter, starts ok.
error message when it trips says short circuit. can't see how.

changing intermediate voltage is the only setting which makes any difference at the moment. too much or too little and the motor won't spin up. and it's not affecting running torque, only start-up.

another thing, i can change how many pole motor it is in settings. research seems to suggest it's a 2 pole due to 50 hz and 2840rpm. but it seems to behave exactly the same on either setting. is there a way to tell for sure without pulling the motor apart and looking at configurations of windings?

where do i get those emoticons? damn, there's no :bangs-head-against-wall: one. aaaarrrggghhh. Noying!

the issue's got to be with the inverter right? i bought the machine off my pal/neighbour who has 3 phase and it was working fine. and the wiring is apparently all good.

oh yeh, and it's not drawing the current it should when it's running.
2.7a when up to speed and 2 pole setting

The motor should be wired directly to the inverter, and the switching done via the inverter. Switching the load on an active inverter is pretty much guaranteed to blow the inverter up.

The motor won't draw the rated current unless running at the rated load, and it's perfectly normal for current to increase during acceleration.
What happens to the current reading when you apply some load to the cutter?

2850rpm makes it a 2 pole motor. For a basic inverter setup, the number of poles shouldn't make any difference.

As above, there should be nothing in the circuit between the motor and the inverter, they don't like being open circuit, just wire a start/stop button to the run input on the inverter if you want to stop it.

Have you checked to see that all the windings are correct, i.e same resistance and meggered them to earth to check if the insulation is still good ?

ok thanks fellas. good info.

i haven't checked the windings and don't know what meggering means.
i will you google it. unles you got a simple explanation how to do it?

finally getting somewhere then. but motor still lacks power.
guess i'll check those things then.

Megger, generic term for insulation resistance, put 500/1000V down the windings to check for resistance, or lack of it to earth, but you probably haven't got one of those then by the sounds of it......

If the motor runs its unlikely to be that to be fair, could be that the motor is in fact shot, or you haven't setup the inverter correctly, pretty hard to tell from behind a keyboard to be fair.

NOTE: Disconnect motor from inverter before doing this !!!

your motor plate states 220/380 this means phase to neutral = 220v
phase to phase = 380v
if the output from your inverter is 220 phase to phase you do not have sufficient volts

220 x 1.732=380 (root 3 x 220)

As above, definitely a 2-pole machine.

You said earlier that when you were running the motor without load, it was going faster than you thought it should be, is this still the case when you change the pole number setting to 2?

How are you setting the speed you want? Is it by setting an RPM figure, or Hz?

To me it sounds like one of the inverter parameters isn't set correctly, and that you are trying to run with too low a voltage for a given speed.

Just checking here, if you run the motor unloaded, what does the inverter say it's output voltage is at full speed? And then at half speed? (It's probably best to run this without any intermediate boost etc)

With the two voltages, the first, full speed one, should be double the voltage of the second.

Cheekyboy - the 220/380 means that it can be set up as either a 220V delta wired motor, or a 380V star wired motor. In both of these circumstances you end up with 220V being placed across each coil, because as you rightly pointed out for a star connected system running at 380V gives 220V phase to neutral, which is what the star point is.

Just checked the manual, and the pole/rpm settings are for user info only, and don't actually affect the running of the inverter.

I'd suggest doing a factory reset on the inverter in case you/somebody else had changed some setting that shouldn't of been, then change only the settings that need changed, which should only be the motor current (PD142). All the other default settings should work fine to test things, and then the only ones I'd be changing would be to configure the start/stop inputs as needed.

As for checking speed, just go by the Hz reading on the display. You can configure the poles/plate RPM so you can see the RPM on the display, but as long as the Hz is at 50, then the motor should be running at the correct speed (squirrel cage motors speed is directly related to the input frequency, so unless the frequency is wrong, the motor speed won't change).

Also, what happens to the current when you apply load to the machine?
How much does it increase, or does the inverter go into current limiting mode?

your motor plate states 220/380 this means phase to neutral = 220v
phase to phase = 380v
if the output from your inverter is 220 phase to phase you do not have sufficient volts

220 x 1.732=380 (root 3 x 220)

Utter tosh, its a 3 phase motor hence the voltage is quoted in 3 phase, the Neutral doesn't even figure in it.

mc
where do you see that pole and rpm settings are for info only. i can certainly change them and when running, the display shows the max rpm i entered.
for that matter, where did you find the manual to look at?

i tried a factory reset and it didn't seems to do it.

not woried about speed any more. it's clearly going at the right speed.

funkynick: "To me it sounds like one of the inverter parameters isn't set correctly, and that you are trying to run with too low a voltage for a given speed."

it seems like that to me too, but still can't figure it out.
i'll go check current under load etc

Just on the off chance this, its not a braked motor is it ?

Does the motor just look like a motor or is there anything else bolted to it ?

Look for a torque boost parameter, I am not convinced it should be in V/F mode either more like constant torque but without seeing the exact application its a difficult one.

don't think so. no add-ons.

is V/F a changeble thing? in constant mode does it just clunk on and 'force' the motor up to speed?

Link to manual -

Although the inverter should of came with a nice thick paper version.

Did you follow the correct instructions for a factory reset?
Go to the correct PD number then enter 08?

PD141 upwards are the motor name plate settings. On a basic inverter like this, the RPM/Poles is only used to display the RPM (and pretty much says that in the manual, although not in the clearest of ways). I'm pretty sure on more advanced inverters with motor sensing (which I've totally forgotten the correct name for right now!), the settings are needed for the detection to work correctly.

Might be worth checking the key voltage values, to ensure all the voltages are indeed set to 220V.

thanks mc
yes did that for reset

aye, i'll triple check those things.

Utter tosh, its a 3 phase motor hence the voltage is quoted in 3 phase, the Neutral doesn't even figure in it.

I never said it did ...........fool ! I was stating the fact that 220v in a 3 phase config gives you 380v across phases.

I never said it did ...........fool ! I was stating the fact that 220v in a 3 phase config gives you 380v across phases.

Thanks, just have a scroll up, that's it, keep going, there you go, see your post now ?

your motor plate states 220/380 this means phase to neutral = 220v

See that word Neutral that you used, you tell me what's that got to do with a 3 phase motor ? Nothing, that's what.

Trying reading what the op originally refers to

i bought a digital 1ph 220V to 3ph 220V converter on ebay to run a dual voltage motor, ie one that can does 380v or 220v .

Its not a dual voltage motor though is it !

Or do you think it is 😆

well looks like i've got it working!

setting Pd145: Auto torque compensation
factory setting 2%, moved it up to 4% and jobsagoodun.
probably put it up a bit more cos it still struggles with rip-sawing.

intermediate voltage is still up a bit. form factory 15v. 24v i think.

speed is fine. just faster that i expected! old machine fro 1978 = quality but not super smooth!

anyway, all good. delta wiring on 220v seems to be fine as my understanding of it suggested it should be.

and stop being children! just try to put your points so celarly that there's no room for misunderstanding.

anyway thanks everyone. i've learned a lot.
jimmer

oh, and what kind of switch should/could i wire in?
the big red shut-of switches that a lot of machines have on them, they have some kind of current to them right? or are they just mechanical cutting live/neut connection?

would be nice to have something chunky and obvious.
anyone post a link to something suitable?

also, can anyone digest the circuit diagram better than me and tell me which of the control circuit terminals are for switching? is it just FOR (forward) for go and and RST (reset) to stop?

Its not a dual voltage motor though is it !

Or do you think it is

Sigh, that's EXACTLY what it is, hence the nameplate states 220/380, the delta winding being 220V the star being 380V, plenty of motors are wound like this, its used by machinery manufacturers so they can make one motor/machine for different markets.

And he hasn't bought a converter, he bought a VSD (Variable Speed Drive) which happens to take 220V single phase in and push 220V 3 phase out.

Go and have read about motors before you try spouting electrical theory again.

Cheers

also, can anyone digest the circuit diagram better than me and tell me which of the control circuit terminals are for switching? is it just FOR (forward) for go and and RST (reset) to stop?

Depends on how its programmed, could be use the RUN terminal closed for run, open it to stop it, RST is for resetting a fault generally

You can use whatever you want to really, just google Inverter or VSD wiring, plenty of examples to get you on your way

RUN ? I meant FOR....

Jamie,

Glad to hear you got it sorted, and I've heard that even some of the guys at my work just end up playing with the settings to get things to work sometimes... although I am surprised that the setting you used makes any difference when the motor is at full speed... but who knows when a manual is written so badly!

Just a thought though, how long is the cable to the motor? If it is too long then this might be why it wasn't working well, and that the extra voltage is enough to get it running.

As for an emergency stop button, we always use normally closed switches which break on operation of the big red mushroom, but looking at the circuit for this it doesn't look like there are any contacts for one of those. Couldn't see anything which gave a description of what the reset does either... so in this case I'd think about having an external e-stop which cut the power to the unit instead.

Cheekyboy, I was trying to explain earlier, but obviously not well enough...

The motor has 3 windings, which can be arranged in a star or delta configuration, and to get the motor to run at it's rated speed and torque it requires 220V across these windings.

Now, in the delta configuration this simply gives us a phase-phase voltage of 220V, and this is the situation we have here.

However, if the motor was connected in a star configuration you now don't have a single winding directly connected between the phases, so to be able to generate 220V across each of the coils, it would now require the 380V phase-phase voltage as you said before.

So, yes, in this case, the motor is designed to be able to run in two different configurations, with two different phase-phase voltages, but both providing 220V across each winding at full speed.

For wiring in switches, I'd wire in E-stop and Start buttons as per the top example on page 37 (page 21 in adobe) ignoring the reverse button bits.
That way you get push button starting, and a failsafe E-stop button/circuit.

There's a few suitable start/stop stations on ebay if you search for "start stop station". Make sure you get one with a raised/unshrouded stop or proper E-stop button, as you just want to be able to hit it, rather than push a recessed button. Also just double check the Stop button comes with a NC (Normally Closed) contact, and the start a NO (Normally open) contact.

I'm assuming this is for personal use, as for commercial use you would have to brake the motor so it stops within 2 seconds (at least I think it's 2) to meet regulations, as well as ensuring the correct guards and spindle heads (i.e. modern safety heads) are fitted.

mc, thanks for bothering to read the manual for me 😳

so like this one then?
http://www.ebay.fr/itm/START-STOP-STATION-2-PUSH-BUTTON-REMOTE-STARTER-CONTROL-PB-STS-/271914921516?pt=LH_DefaultDomain_3&hash=item3f4f646e2c

and yeh, so it is those terminals with their settings selected for correct functions. looks simpl enough

i'm using it for work, but only me using in my workshop in my house.
safety inspection not big in france too.

That control should work nicely.

French do seem to a bit more lax in their safety inspections, regardless if the spindle has the old style heads (whitehill?) you'll probably struggle to get cutters for them. The problem with the old heads is if the blades aren't tightened they can be ejected at great speed, and if you get a limb caught in the blade/head, the nature of them will pull you in. Modern heads the blade bolts have to physically come out before the blade can be ejected (you should notice it rattling long before then), and have a kickback that should knock any limbs away from the cutter rather than pull them in.

I do know somebody who still uses the old style heads, as they've got a large selection of profile blades, but they know if H&S see them, they'll have a lot of explaining to do.
I happen to have a twin head spindle moulder buried in the shed for about 10 years now. Only came to get the spindle bearings changed, and was never collected.

thanks mc,
it only came with 2 heads, neither seems up to much.
i'll get new ones from axminster/wherever as an when i need them. will be mostly saw and planer/thicknesser it get used for initially

Sigh, that's EXACTLY what it is, hence the nameplate states 220/380, the delta winding being 220V the star being 380V, plenty of motors are wound like this, its used by machinery manufacturers so they can make one motor/machine for different markets.

Star and delta are configurations that are arranged via the connection terminals and are used depending upon the torque requirements, it has nothing to do with the winding configuration within the motor and has absolutely nothing to do with differing markets Sigh 🙄

Cheekyboy, do you want to get out hole just now, or do you want to keep digging?

it does have to do with different markets historically achly, so i've read.
3 ph in the states being 220v.

people say winding configuration to [i]describe[/i] star and delta, because [i]in effect[/i] you are changing the winding configuration when you flip between the 2.

not sure sure about torque requirments but on this machine, and many other it is used for EXACTLY that purpose, as stated on name plate. it's a dual voltage motor; you can change between star and delta [i]winding configurations[/i] in order to be able to change between voltages.

but funkynick and tragically have already said all that. i just wanted to say it again.
i've got some good spades if you need one

not sure sure about torque requirments but on this machine, and many other it is used for EXACTLY that purpose, as stated on name plate. it's a dual voltage motor; you can change between star and delta winding configurations in order to be able to change between voltages

Power is generated using 3 phase machines/alternators/generators, supplied to most consumers at 400v AC 50HZ - FACT

SOME PREMISES RECEIVE 11000VAC 50HZ -FACT

Industrial premises, non domestic properties are supplied with 3 phase supplies normally 400Vac 3ph 50hz - Fact

Most ac motors for industrial applications are 400vac 3 ph 50hz regardless of the wiring -Fact

Small power and lighting, domestic heating, domestic appliances use single phases 230v ac

The op has used an inverter supply to replicate the 3 phases as he only has a single phase supply at home or his premises

Again for clarity 230 x root 3 = 398.371685741 (400) the 3 phase are 120 deg apart, if you measure across any two phases you will read 400v, across 1 phase to neutral or earth 230 v. This is not dual voltage !

This is totally regardless of how you wire your motor terminals star or delta.

but here, since i'm in france, we're dealing with 3ph normally at 380v and domestic at 220v. fact

most of what you say in your last post we all know and agree with, but please explain some things for me:

[i]What is[/i] dual voltage then?

Why do these motors have delta and star options?

Cheekyboy, I suggest you get hold of a 3 phase motor with the same ratings as jamiesilos, connect it on delta configuration and then apply 400v 3 phase supply. Please let us know your findings after you have done it.

as i understand it:
when in star config. with a 380v supply, the motor is putting the 220v from each phase to neutral, across each winding.

whereas in delta, with a 220v (3ph) supply, as is the case here, the motor is putting the 220v phase to phase accross each winding.

so if the motor's only ever [i]using[/i] 220v, what's the point in giving it 380v? well it uses less current, and therefore less power, so is safer and cheaper.

right?

i think we all agree about that stuff essentially

but cheekyboy, i think that's what's commonly called a [i]dual voltage[/i] motor, even though the voltage being used across the windings to drive the motor is 220v in both configurations.

this is where i learned it:
http://www.allaboutcircuits.com/textbook/alternating-current/chpt-10/three-phase-y-delta-configurations/

What is dual voltage then?

Dual voltage normally refers to equipment that operates off two different supply voltages and normally has a switch to allow switching between the two, some domestic appliances have this to allow more varied used across countries.

Why do these motors have delta and star options?

This depends upon the load to be driven, the starting torque of a stationary motor and the resultant current draw may adversely effect other equipment, think big factories etc with lots of motors stopping and starting, often they are set up with star/delta starter controls, this will start the motor in star config and switch to delta (via a timer circuit) once the motor has started to run.

In my line of work we use inverter drives as variable speed drives on cooling fans etc, these are mainly wired in delta as the inverter will soft start the motor, this can also be used to negate the use of a star/delta starter control.

Whichever way you look at within your motor you will have 380v swilling around.

I wasnt aware you were in France hence the slight difference in voltages

Ok if you go and measure across L1 and L2 on your inverter output terminals you should read 380v ac likewise across L2 - L3, L1-L3.

This voltage is the sum of L1, L3, and L3 but due to the fact that the 3 alternating voltages are spaced 120 degrees apart it is not a simple addition hence my continued use of the root 3 (being 1.732) being the factor used to combine the 3 voltages.

The diagram halfway down the page shows what I am trying to explain.

http://electrical-engineering-portal.com/basics-of-3-phase-induction-motor-1

Cheekyboy... you are getting confused between two different things here...

a) a motor which is designed to run, as I have said at least twice before, at it's rated speed with a voltage across each winding, irrespective of the winding configuration, of 220V.

In this case, if you configure it as delta, you have a phase-phase voltage of 220V, or a star you have a phase-phase voltage of 380V. In both cases the power, torque and everything else on the machine is the same, although obviously the current is lower for the star wound machine.

b) a motor which is designed to be switched between star and delta configurations with the same voltage being applied across the terminals, irrespective of the configuration. In these cases, it's generally used in star configuration to get high torque, lower speed starting, then moving onto delta for high speed running.

The reason for doing this is that you can then use the same inverter, generating the same maximum voltage, to overcome the lower back EMF from the motor when setup as delta as you are only having to deal with the back EMF of a single winding, and not sqrt(3) * back EMF as you would get in star.

Okay, so that's probably not very well described, but I have been sampling our homemade elderflower champagne this evening!!! Hic!

Cheeky, you really don't get the concept of the dual voltage ratings.

As has already been explained, on a typical 220/380V rated motor, each coil needs 220V. In star wiring, that's done by applying 380V to the end of each point, which due to the 120deg phasing, results in 220V across each coil. In delta mode, you only have to apply 220V to each point to achieve the same.

Connect 380V to said delta connected motor, and you'll quite quickly have a nice smouldering lump of resin/copper/iron/aluminium that used to be a functioning motor, as you've just applied nearly twice the rated voltage to each coil.
Or if you're so confident everybody is wrong, feel free to video yourself wiring a 220/380V motor in delta, wiring it up to 380V 3 phase, and switching it on for a few minutes. I'd personally quite like to see just how quickly it starts smouldering.

As for torque and power output, they're the same at both voltages provided the motor is in the correct coil configuration for the applied voltage.

As for star delta starters, the whole point of them is to reduce start up current by having the motor run in a star connection until the motor is up to speed, and then switch to delta. Now if you had ever paid attention, motors designed for star delta starting using normal UK 3 phase, are 400/690V dual voltage motors. Off course the downside to star delta starting is you reduce start up torque, because the motor coils are not receiving their rated voltage, but you greatly reduce the current surge caused by hard starting at full voltage.

Cheekyboy... you are getting confused between two different things here...

a) a motor which is designed to run, as I have said at least twice before, at it's rated speed with a voltage across each winding, irrespective of the winding configuration, of 220V.

In this case, if you configure it as delta, you have a phase-phase voltage of 220V, or a star you have a phase-phase voltage of 380V. In both cases the power, torque and everything else on the machine is the same, although obviously the current is lower for the star wound machine.

b) a motor which is designed to be switched between star and delta configurations with the same voltage being applied across the terminals, irrespective of the configuration. In these cases, it's generally used in star configuration to get high torque, lower speed starting, then moving onto delta for high speed running.

The reason for doing this is that you can then use the same inverter, generating the same maximum voltage, to overcome the lower back EMF from the motor when setup as delta as you are only having to deal with the back EMF of a single winding, and not sqrt(3) * back EMF as you would get in star.

Okay, so that's probably not very well described, but I have been sampling our homemade elderflower champagne this evening!!! Hic!

Gibberish, pure unadulterated gibberish 🙄

Connect 380V to said delta connected motor, and you'll quite quickly have a nice smouldering lump of resin/copper/iron/aluminium that used to be a functioning motor, as you've just applied nearly twice the rated voltage to each coil.

Eh ! are you saying that in France they have single phase supplies at 380 v ?

when in delta you are connecting two phases to one set of windings !

see the connection diag halfway down the page
http://www.hwl-technical-solutions.com/motorsandpumps.aspx

goodnight sweetdreams

Eh ! are you saying that in France they have single phase supplies at 380 v ?

when in delta you are connecting two phases to one set of windings !

And yes, those are a lovely set of configuration diagrams, and highlights exactly how a star delta starter gets connected. But as I mentioned above, that motor would essentially be a 400/700V rated motor. Each coil of that motor is rated at 400V, and the 230V is only shown to represent what is present at the star point during the star phase to highlight how the star phase reduces the applied voltage across each coil, it's got nothing to do with the voltage rating of that motor.

On a 230/400V motor, each coil is rated at 230V, not 400V.

Well, I tried... and if I am talking complete gibberish, I'd best hope the guys at work don't find out!

Oh, and good luck mc!

Each coil of that motor is rated at 400V, and the 230V is only shown to represent what is present at the star point during the star phase to highlight how the star phase reduces the applied voltage across each coil, it's got nothing to do with the voltage rating of that motor.

Absolute classic................star phase fantastic !

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

if i wired the motor in star the voltage would be too low, as you said earlier cos it's only a 380v supply.

this is the case here. ok, maybe this isn't what you think of as a dual voltage motor, but that is how this motor works and is intended to work

Oh, and good luck mc!