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Discuss what do these 380v wiring colours mean, I want to use with a 220v vfd. it may have had speed control in the Electrical Forum area at ElectriciansForums.net

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Hello, I am a woodworker who has got a large old power feed, its 380v and i want someone to rewire to a 220v vfd for me, can someone please tell me what these old colour codes mean. I bought the machine in Scotland.I can't find any easy diagrams online.I think its a good few years old.Thank you!

1 2 3 4 5 6 7
 
TL;DR
see pic of old wiring , what do the colours mean?> typically?
1 2 3 4 5 6 7, it may have had speed control?

James

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Most likely you have a star delta wired motor. The 6 wires plus green/yellow (earth) are the ends of 3 separate windings.

It is a little to complex to explain on a forum but it is unlikley to be possible to use a single phase vsd, you will probably need a 3 phase one or a new motor.

To confirm, can you post a pic of the motor rating plate?
 
  • Thread Starter Thread Starter
  • #3
Most likely you have a star delta wired motor. The 6 wires plus green/yellow (earth) are the ends of 3 separate windings.

It is a little to complex to explain on a forum but it is unlikley to be possible to use a single phase vsd, you will probably need a 3 phase one or a new motor.

To confirm, can you post a pic of the motor rating plate?
Thank you, i will do that tommorow.
 
No you cannot just rewire a three phase motor so it will run on a single phase supply,
you can how ever get a electronic convertor / motor speed control
not cheap mind you but will work splendidly
 
  • Thread Starter Thread Starter
  • #5
Most likely you have a star delta wired motor. The 6 wires plus green/yellow (earth) are the ends of 3 separate windings.

It is a little to complex to explain on a forum but it is unlikley to be possible to use a single phase vsd, you will probably need a 3 phase one or a new motor.

To confirm, can you post a pic of the motor rating plate?
79323948_2394291114215533_5123692591656730624_n.jpg79433539_1195855287284895_7711502475890524160_n.jpg79680116_561356141317943_5203009784231493632_n.jpg

Thank you, I think i see what you mean about complicated. View: https://www.youtube.com/watch?v=h89TTwlNnpY


I will have to work out what motor to replace it with, guessing if it is a stardelta motor arrangement this would have to have a separate panel with switches and timers? and 3 phase., this is likely too expensive for me to setup. I need to figure out an alternative to closely match performance, if you could let me know what I should look for off the name plate, that would be amazing.

Iv tried to take good pics, its very shiny and hard to read.

The two pics are of the left and right sides of the plate.

If you're not able to read it, please let me know and I will write it out.

Thanks a million.
 

James

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Ok, it’s got 6 windings inside, wires star, star.
An unusual setup for such a small motor.
Y is the symbol for star and the triangle is the symbol for delta.

It is probably cheaper to replace the motor with a single phase motor.
Unless you need variable speed.
In that case I would go for a 3ph 230v motor and a vfd

I can’t see any numbers after the triangle n the voltage area of the plate.
Post automatically merged:

Something like this might do you well
You will have to check dimensions and shaft size etc

 
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  • Thread Starter Thread Starter
  • #7
Thank you very much.

These numbers read off the plate.

380yy delta

0.25kw

1370/80 rpm? I can detach from the gearbox

0,75/0,75 A
Co's 84/.62

Ip44

Have read these straight off

I'm new to motors, 3ph 3 phase 240 v motor

What horsepower or or kw.

How do I know the torque required?

It powers 9 wheels via sprockets and chains. It needs to be strong.

I might have to get a custom mounting plate made.

It's worth getting it working but is there a way I can get a suitable 240v motor at variable speed and suitable torque?






Ok, it’s got 6 windings inside, wires star, star.
An unusual setup for such a small motor.
Y is the symbol for star and the triangle is the symbol for delta.

It is probably cheaper to replace the motor with a single phase motor.
Unless you need variable speed.
In that case I would go for a 3ph 230v motor and a vfd

I can’t see any numbers after the triangle n the voltage area of the plate.
Post automatically merged:

Something like this might do you well
You will have to check dimensions and shaft size etc

 

James

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Take the original to a local industrial motor supplier and ask for a replacement to your spec. They will be able to sell you something suitable.
£100 to £150 would be my guess
 
  • Thread Starter Thread Starter
  • #9
Thanks a million for helping
Next step decide if I need variable speed control :)

Torque, can we tell what it currently is off the plate?


Will do that re supplier thanks!



Take the original to a local industrial motor supplier and ask for a replacement to your spec. They will be able to sell you something suitable.
£100 to £150 would be my guess
 

Simon47

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I think that motor will connect as 230V delta and run fine from a variable frequency drive - 380V Y is about 225V delta. The 240V single phase input VFDs drives only output 240V 3P, they don't step up to 415V.
I assume there's a terminal box with a cover you can remove ? Please post a photo of the inside of that showing clearly what's currently connected - and if there's a diagram inside the lid, post a photo of that as well.
 

Lucien Nunes

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I think it's a dual-speed pole-changing motor!

  • The speeds are probably 1370 / 680 rpm (not 80, which looks like it means the gearbox output but I don't think that's correct). Please could you look closely at the plate and see if it is in fact 680.
  • The configuration is shown as YYΔ I.e. there are two sets of 3-phase windings for the two speeds.
  • It gives two equal values for line current (both 0.75A) and two values for cos φ, one of which is much lower than the other (that's usually the low speed).

If it were a single-speed motor designed to run in either 230V delta / 380V star, it would show both voltages and two different line currents. If I am correct, then it requires 380V for normal running in delta and cannot be operated directly from a 230V single-to-three-phase inverter.

Let's see inside the terminal box!
 
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  • #12
Thanks all, this is great to have your input.

Opened the casted cover and found:
I can retake photo again if wires are too hard to see, seems like 3 are joined across with solder. A german friend translated for me.???
3-phase-wiring-question.png

see.3.jpg1.jpg1.jpg


I think that motor will connect as 230V delta and run fine from a variable frequency drive - 380V Y is about 225V delta. The 240V single phase input VFDs drives only output 240V 3P, they don't step up to 415V.
I assume there's a terminal box with a cover you can remove ? Please post a photo of the inside of that showing clearly what's currently connected - and if there's a diagram inside the lid, post a photo of that as well.
Post automatically merged:

I think it's a dual-speed pole-changing motor!

  • The speeds are probably 1370 / 680 rpm (not 80, which looks like it means the gearbox output but I don't think that's correct). Please could you look closely at the plate and see if it is in fact 680.
  • The configuration is shown as YYΔ I.e. there are two sets of 3-phase windings for the two speeds.
  • It gives two equal values for line current (both 0.75A) and two values for cos φ, one of which is much lower than the other (that's usually the low speed).

If it were a single-speed motor designed to run in either 230V delta / 380V star, it would show both voltages and two different line currents. If I am correct, then it requires 380V for normal running in delta and cannot be operated directly from a 230V single-to-three-phase inverter.

Let's see inside the terminal box!

Thank you
i just checked,you're right it is 680 (very hard to see), there are nine wheels with sprockets and chain, is that the speed control? the speed needed, im guessing 50 - 100 rpm
 

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Lucien Nunes

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The terminal diagram cast into the cover is a generic one, showing the normal options of star for high voltage and delta for low. However, it may not actually apply to your motor, as such a configuration would invariably also be indicated by the two voltages being stamped on the plate, whereas you only have 380V.

Do you have a multimeter? If so, please could you confirm which terminals show continuity to which others.

If you look at the black terminal block moulding there are terminal labels moulded in next to the studs. Probably something like:
U1-V1-W1
V2-W2-U2
Or its mirror image.

If you have continuity U1-U2 and V1-V2 and W1-W2 but not U1-V1 then the dual speed thing may be a red herring.

If you have continuity U1-V1-W1 and U2-V2-W2 but not U1-U2 then it is indeed a dual winding, dual speed motor. The speeds would be selected with a 3-pole changeover switch on the panel.
 
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  • #14
The terminal diagram cast into the cover is a generic one, showing the normal options of star for high voltage and delta for low. However, it may not actually apply to your motor, as such a configuration would invariably also be indicated by the two voltages being stamped on the plate, whereas you only have 380V.

Do you have a multimeter? If so, please could you confirm which terminals show continuity to which others.

If you look at the black terminal block moulding there are terminal labels moulded in next to the studs. Probably something like:
U1-V1-W1
V2-W2-U2
Or its mirror image.

If you have continuity U1-U2 and V1-V2 and W1-W2 but not U1-V1 then the dual speed thing may be a red herring.

If you have continuity U1-V1-W1 and U2-V2-W2 but not U1-U2 then it is indeed a dual winding, dual speed motor. The speeds would be selected with a 3-pole changeover switch on the panel.

Thank you very much for taking the time to explain this, I don't have a multimeter but either way I have to organise a single phase 240v motor(preferably with speed control.
I don't have access to 3 phase.

How do I work out what is a good replacement, is another generic .25 kw motor ( with correct form factor (and shaft location) with speed of
1370 / 680 rpm the way to go?
 
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  • #15
Thank you very much for taking the time to explain this, I don't have a multimeter but either way I have to organise a single phase 240v motor(preferably with speed control.
I don't have access to 3 phase.

How do I work out what is a good replacement, is another generic .25 kw motor ( with correct form factor (and shaft location) with speed of
1370 / 680 rpm the way to go?
Is this on the right track?

 

Lucien Nunes

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On the subject of the original motor, I've missed a trick. I'm convinced now it's a Dahlander consequent pole 2-speed motor, which runs in double-star at full speed and in series delta at low speed with equal torque. You won't need the low speed mode as the VSD will do that for you, so you could run it on a 230V inverter by swapping the internal interconnections between the two winding groups so that the same relative coil polarities as are currently obtained in star are obtained in delta instead. That would give you a single-speed, 230V delta motor of full power rating. If you wanted to go down this route, I would need to see very detailed pics of the internal winding leadouts, and we would have to pick through them with a continuity tester very carefully to ensure we make the right interconnections.
 
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  • #17
On the subject of the original motor, I've missed a trick. I'm convinced now it's a Dahlander consequent pole 2-speed motor, which runs in double-star at full speed and in series delta at low speed with equal torque. You won't need the low speed mode as the VSD will do that for you, so you could run it on a 230V inverter by swapping the internal interconnections between the two winding groups so that the same relative coil polarities as are currently obtained in star are obtained in delta instead. That would give you a single-speed, 230V delta motor of full power rating. If you wanted to go down this route, I would need to see very detailed pics of the internal winding leadouts, and we would have to pick through them with a continuity tester very carefully to ensure we make the right interconnections.
:)You're Brilliant! if you're up for a challenge I can follow your instructions to a tee,its a beast of a power feed, aprox 120 kg. I will need to get a mulitmeter/continuity tester, I presume I need to unmount from the gearbox and open it up and take pics of the windings?
Im a trained engineering technician but complicated electrics not my forte:)
 

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Lucien Nunes

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Disclaimer:
Some time will need to be invested to find out whether it is possible at all.
There is a high risk of accidental error with the windings as there are millions of permutations of 12 wires (six windings each with two ends). If they get mixed up or we mis-identify them, it will be slow and tricky to identify the proper phasing again without specialist equipment. Getting one winding out of phase for example, could result in poor torque, blown fuses, burnout, inverter destruction or all of the above. So proceed at your own risk.

As there only seems to be one lead from inside the motor to each terminal stud (please confirm), the connections must be within the end bell so you would have to get inside there to swap them over. If they are hidden or bound up with winding tape it could be tricky. I suppose you've nothing to lose by looking inside though.

@marconi @Marvo @darkwood and anyone else please check my logic:

a) It has to be a Dahlander connection as-is.
b) There are 6 leads in the terminal box for 12 winding ends so they must be paired internally into series delta.
c) The edges of the delta (2U, 2V, 2W) can remain connected as-is, as this gives the right relative polarity of both windings of each phase for high-speed.
d) The corners of the delta (1U, 1V, 1W) need to be split so that the two windings of each phase can be paralleled.
e) The paralleled windings can then be connected in delta to make a 3-lead 230V motor.

One snag we have now is that we don't know for certain which set of leads are the edges and which are the corners. We might assume that terminal block 1U= winding U1 = corner terminal etc but there's no guarantee because the original speed switching has been disconnected. If we can see the windings leading out from their respective coils, that's fine. Otherwise we might have to use a battery and compass in the bore, or feed in low voltage AC e.g. from a bell transformer and find coil phasing by searching with a voltmeter.

I'll post a diagram later.
 
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  • #19
Disclaimer:
Some time will need to be invested to find out whether it is possible at all.
There is a high risk of accidental error with the windings as there are millions of permutations of 12 wires (six windings each with two ends). If they get mixed up or we mis-identify them, it will be slow and tricky to identify the proper phasing again without specialist equipment. Getting one winding out of phase for example, could result in poor torque, blown fuses, burnout, inverter destruction or all of the above. So proceed at your own risk.

As there only seems to be one lead from inside the motor to each terminal stud (please confirm), the connections must be within the end bell so you would have to get inside there to swap them over. If they are hidden or bound up with winding tape it could be tricky. I suppose you've nothing to lose by looking inside though.

@marconi @Marvo @darkwood and anyone else please check my logic:

a) It has to be a Dahlander connection as-is.
b) There are 6 leads in the terminal box for 12 winding ends so they must be paired internally into series delta.
c) The edges of the delta (2U, 2V, 2W) can remain connected as-is, as this gives the right relative polarity of both windings of each phase for high-speed.
d) The corners of the delta (1U, 1V, 1W) need to be split so that the two windings of each phase can be paralleled.
e) The paralleled windings can then be connected in delta to make a 3-lead 230V motor.

One snag we have now is that we don't know for certain which set of leads are the edges and which are the corners. We might assume that terminal block 1U= winding U1 = corner terminal etc but there's no guarantee because the original speed switching has been disconnected. If we can see the windings leading out from their respective coils, that's fine. Otherwise we might have to use a battery and compass in the bore, or feed in low voltage AC e.g. from a bell transformer and find coil phasing by searching with a voltmeter.

I'll post a diagram later.
Mega cool of you and the forum! I fully accept this might not be possible or work at all. I will get to work removing it from gearbox and sharing all the info depth info u need. I wanted to know more about motors, this is a premium learning exercise!
X mas is coming up fast, understand if this waits until NY. Again amazingly cool of you and the forum. :)
 

James

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wow, you are getting not beyond my understanding but certainly out of my comfort zone.

not sure if I understand correctly what you are referring to when describing the windings but have got as far as this poorly drawn representation. left (as is) right (convert to)

am I with you so far?

its been a long time since I was sat in a hall figuring out if it was the left hand or right hand that I should be putting into silly positions for the solution.
 

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marconi

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I reckon you have this motor winding set up(Dahlander/pole changing) as in the attachment.

The six wires are brought out to the 6 terminals as the triplets 1V, 1U and 1W and 2U, 2V and 2W and connected as in the diagram at attachment.

To effect pole changing one swaps the 3 lines L1, L2 and L3 between these triplets and when the lines are connected to 2U, 2V and 2W one connects 1U, 1V and 1W together.

3 Lines to the series delta is for slow speed by making an 8 pole(4 pole pairs) machine with speed of 750 rpm and 3 lines in parallel star for 4 pole (2 pole pairs) with sync speed of 1500 rpm.
Post automatically merged:

The motor terminal is:
W2 U2 V2
U1 V1 W1

but photographed upside down

W1(Blue) V1(Green) U1(Orange)
V2(Brown) U2(Black) W2(Gray/Light Brown)
 

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I reckon you have this motor winding set up(Dahlander/pole changing) as in the attachment.

The six wires are brought out to the 6 terminals as the triplets 1V, 1U and 1W and 2U, 2V and 2W and connected as in the diagram at attachment.

To effect pole changing one swaps the 3 lines L1, L2 and L3 between these triplets and when the lines are connected to 2U, 2V and 2W one connects 1U, 1V and 1W together.

3 Lines to the series delta is for slow speed by making an 8 pole(4 pole pairs) machine with speed of 750 rpm and 3 lines in parallel star for 4 pole (2 pole pairs) with sync speed of 1500 rpm.
Post automatically merged:

The motor terminal is:
W2 U2 V2
U1 V1 W1

but photographed upside down

W1(Blue) V1(Green) U1(Orange)
V2(Brown) U2(Black) W2(Gray/Light Brown)
thanks very much!

does that mean that this is not a
star delta wired motor? or that is the same as a
Dahlander/pole changing

how does the pole changing happen? is it in a fixed position by replacing physical wires or a switch of somekind?
 

marconi

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The motor terminal is:
W2 U2 V2
U1 V1 W1

but photographed upside down

W1(Blue) V1(Green) U1(Orange)
V2(Brown) U2(Black) W2(Gray/Light Brown)

SpeedtStu - As LN said and I concur, the motor windings are arranged for (Dhalinder pole change )and not star then delta for start then run operation. Could you tell us how many internal wires are attached to each terminal - it looks like only one indicating as LN said that there are internal connections between "2U-2V, 2V-2W and 2U -2W; but they may be other connections under the terminal block. Could you undo the two chrome slotted screws and have a look underneath for any more connections?

Otherwise the motor will have to opened up to access these pairings, severe them and reconnect them differently to form a parallel delta arrangement of windings able to be energised at 230V line-to-line.

Sorry rushed at the moment have to go picj the wife up from choir practice - the pole chamging is done by switching the incoming 3 lines between tge triplets I mentioned earlier and when in one of those configurations connecting together three nodes as I mentioned. If yu stare at the doagram I showed and imagined defroning it by pulling 2U, "2V and 2W in three directions angles 120 degrees apart away from the controid you can see how it can swap between series delta and parallely star and the 1U and 1W and 1U vertices come together .
 
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  • #24
The motor terminal is:
W2 U2 V2
U1 V1 W1

but photographed upside down

W1(Blue) V1(Green) U1(Orange)
V2(Brown) U2(Black) W2(Gray/Light Brown)

SpeedtStu - Could you tell us how many internal wires are attached to each terminal - it looks like only one indicating as LN said that there are internal connections between "2U-2V, 2V-2W and 2U -2W; but they may be other connections under the terminal block. Could you undo the two chrome slotted screws and have a look underneath for any more connections?

Otherwise the motor will have to opened up to access these pairings, severe them and reconnect them differently to form a parallel delta arrangement of windings able to be energised at 230V line-to-line.
i will do that tomorrow in good light, i can do all of the above with instructions. You're all superstars!
 

marconi

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See attached image first.

If one takes the transform of the star configuration to the delta configuration
and use the nomenclature u1 and u2 as the start an ends of U1 and u3 and u4 as the start and ends of winding U2 - similarly for V1, V2, W1 and W2, then for star

L1 - u1, L2 - v1, L3- w1 and star is u2 - v2 - w2.

Transforming to delta the winding ends are connected:

L1 - u1 and L2 - u2
L2 - v1 and L3 - v2
L3 - w1 and L1 -w2

If one uses the same transform for the parallel star arrangement to a parallel delta arrangement one has for star:

L1 - u4 - v1
L2 - v4 - w1
L3 - w4 - u1

and star point is u2 - u3 - v2 - v3 - w2 - w3

which transforms to a delta of:

L1/2U terminal - u2 - w3 - (u4 - v1)
L2/2V terminal - v2 - u3 - (w1 - v4)
L3/2W terminal - v3 - w2 - (u1 - w4)

where the winding ends in brackets () are already connected as required to L1, L2 or L3 but those not in brackets viz u2, u3, v2, v3, w2, w3 are not connected as required. At the moment the connections are made (u2-u3), (v2-v3) and (w2-w3) which are the corners of the low speed delta configuration. As Lucien said these pairings need to be accessed, severed and reconnected as shown above in bold.

Or I have made a complete Horlicks..... :)
 

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  • #26
See:

How to connect 3 phase motors in star and delta connection - Quora - https://www.quora.com/How-do-I-connect-3-phase-motors-in-star-and-delta-connection

If one takes the transform of the star configuration to the delta configuration
and use the nomenclature u1 and u2 as the start an ends of U1 and u3 and u4 as the start and ends of winding U2 - similarly for V1, V2, W1 and W2, then for star

L1 - u1, L2 - v1, L3- w1 and star is u2 - v2 - w2.

Transforming to delta the winding ends are connected:

L1 - u1 and L2 - u2
L2 - v1 and L2 - v2
L3 - w1 and L1 -w2

If one uses the same transform for the parallel star arrangement to a parallel delta arrangement one has for star:

L1 - u4 - v1
L2 - v4 - w1
L3 - w4 - u1

and star point is u2 - u3 - v2 - v3 - w2 - w3

which transforms to a delta of:

L1/2U terminal - u2 - w3 - (u4 - v1)
L2/2V terminal - v2 - u3 - (w1 - v4)
L3/2W terminal - v3 - w2 - (u1 - w4)

where the winding ends in brackets () are already connected as required to L1, L2 or L3 but those not in brackets viz u2, u3, v2, v3, w2, w3 are not connected as required. At the moment the connections are made (u2-u3), (v2-v3) and (w2-w3) which are the corners of the low speed delta configuration. As Lucien said these pairings need to be accessed, severed and reconnected as shown above in bold.

Or I have made a complete Horlicks..... :)
I am sorting out a multimeter as you guys wow me again, this is very cool of you all. I'll do my best to pull it off. Thanks again!
 

marconi

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Lucien: My analysis indicates that the windings (U1, V1, W1) are wound in the same way so that the same current flowing from 1 to 2 produces the same direction of magnetic field.

The windings (U2, V2, W2) are wound in the opposite direction to U1, V1, W1 which means to produce the same direction of magnetic field as U1, V1, W1 the current must flow 4 to 3.

To produce a conventional pole pairs using parallel delta, the windings (UV, UW, VW) are connected in parallel by connecting 1 to 4 and 2 to 3; this creates the same direction of magnetic field in each coil. This is what is seen in my #25 (if you draw it out - see my scribbled attachment and note #). The current flow then through say the pair V1 and W3 is in opposite directions but the coils are wound opposite way to each other so magnetic field combine. The Ampturns of V1 and W3 are in the same direction.

This is just what we want for the 230V line to line parallel delta configuration for the creation of conventional pole pairs (high speed).

As a quick check slow speed by consequent pole generation would now be series star but require 400V line to line and the coils would be connected in series as say u1 U1 u2 w3 W2 w4.

Note #: The arrows indicate the magnetic field direction for current flows 1 to 2 or 3 to 4.

I could have made a mistake though so do point it/them out to me ....
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wow, you are getting not beyond my understanding but certainly out of my comfort zone.

not sure if I understand correctly what you are referring to when describing the windings but have got as far as this poorly drawn representation. left (as is) right (convert to)

am I with you so far?




James - see attachment in my #26. LN is suggesting (cleverly) converting the 380V line to line parallel star high sync speed winding configuration as is (-you showed a series star) into a to be 230v line to line parallel delta (which you did draw).
 

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Lucien Nunes

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Crikey, I was only asking for a yes or no!
I'll look later, I have two machine breakdowns which are holding a job up.

In the meantime, I'll add a note about safety. If the original controls are missing and being replaced by the inverter, you are modifying the machine in a safety-critical way. There are all sorts of regulatory implications if you use the machine in a place of work or sell it. If the new controls and mode of operation are not compliant (and proven to be compliant), it may be a breach of various regs to install, operate or sell it. I will leave all those implications for you to work out. My only interest here is to investigate the motor and identify whether it can be reconfigured to run on 230V.
 
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  • #29
Crikey, I was only asking for a yes or no!
I'll look later, I have two machine breakdowns which are holding a job up.

In the meantime, I'll add a note about safety. If the original controls are missing and being replaced by the inverter, you are modifying the machine in a safety-critical way. There are all sorts of regulatory implications if you use the machine in a place of work or sell it. If the new controls and mode of operation are not compliant (and proven to be compliant), it may be a breach of various regs to install, operate or sell it. I will leave all those implications for you to work out. My only interest here is to investigate the motor and identify whether it can be reconfigured to run on 230V.
Thanks everything so far. To confirm this will only be used in my own private workshop :) I've ordered a multimeter today and will start getting all the pics together, it would be a very cool project to work with you all on. Great piece of machinery to have working.
 

Lucien Nunes

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Fixed my breakdowns, one was an intermittent internal break in an encoder cable, other was a configuration problem.

You are correct that star-delta pole-changing is fundamentally different from star-delta starting. Star-delta starting is a method applied to a conventional 3-phase motor, while pole-changing is a function of a specially built 2-speed motor. What they have in common is the use of switching to rearrange the winding connections.

Star-delta starting is a basic soft-start method used with regular single-speed 3-phase motors that have one group of three windings rated for the full line-line voltage. When connected in star for starting, each 400V winding receives only 230V, reducing the starting current and torque. After a sufficient run-up time, the starter reconnects the windings into delta so that each winding receives the full 400V and full torque is available.

A pole-changing motor is specially constructed to deliver two speeds at the turn of a switch. The Dahlander configuration provides a simple and convienent way to alter the phasing and the voltage per winding with the minimum of switch contacts, suitable for motors with 2:1 speed ratio and windings rated for the line-neutral voltage. It does not offer a soft-start as such, which would require a more extensive switching system and probably be redundant on a typical small pole-changing motor.

Inverter drives make both techniques obsolete, because they can provide both soft starting and selectable fixed running speeds. For use with a 400V output inverter, a motor originally wired for star-delta starting can be left in delta (full power) and a Dahlander motor can be left in star (high speed) and controlled exclusively by the VFD. The standard motor could optionally be reconfigured for 690V in star, and the Dahlander motor 230V in delta, which is what we are looking to achieve here.
 

Reply to what do these 380v wiring colours mean, I want to use with a 220v vfd. it may have had speed control in the Electrical Forum area at ElectriciansForums.net

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