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3-phase
- Thread starter altec
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Big_Spark
Stod said:
Stod, please read it correctly, I have the information ON PAPER in front of me and it is on the website.
I will accept people disagreeing with me, but this is simply insulting. Vent Axia market the same motors as single or three phase, depending on their connections in the factory, but they are IN FACT the same motor and they cost the same price..We paid £328.54 plus VAT from CCL Veloduct for it. We needed a single phase unit URGENTLY, and Vent Axia contacted their suppliers and found that only CCL had one in stock, but it was a three phase unit, all it meant was rearranging the links to convert it to single phase use, and it was sold to us as a TP450-14, even though it had been packaged as a TP450-34.
In case your wondering,
TP = Turboprop
450 = Casing outer diameter in mm
1 or 3 = winding link configuration
4 = Poles in the motor.
here
If you find this totally baffling then perhaps you would care to phone Vent-Axia tomorrow and talk to them, they will confirm that the two models are in fact one and the same and that it is the link configuration that makes the difference.
FWL you missed the point, those examples you quote as you said above are specially wired internally at the factory and are not plain motors when i picked up on your quotes it was referring to the principles behind plain bog standard motors and not any modified types, with enough technology behind it you could get a 12v shaded pole motor running on three phase(and that's at 415volts)! but the motor will not be seeing the initial three phase supply and that is the point.
We are talking motor principles here.
We are talking motor principles here.
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Stod
FWL_Engineer said:
Insult? All I’ve said is that I do not know of any induction motors that are designed to operate on both single and three phase, so could FWL quote a url. He did so in reply to Kendor, but Vent-Axia’s specification does not support FWL’s assertion. It says that fans are available in 1 OR 3 phase and has two separate tables for the performance of single and three phase versions of the fans.
I just pointed this out. If that’s an insult, then it’s far less an insult than FWL dishes out regularly to other contributors to this forum.
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Big_Spark
Stod, please use the link in my last post and you will see the very point I was making, and you will see your previous post was incorrect.
Kendor, there is nothing special about the way in which Vent-axia manufacturers it heavy duty motors, all three phase motors will run on single phase if the windings are linked out correctly, that is a plain and simple fact.
I agree that a DEDICATED single phase motor with a single winding will never run of three phase in the normal way, although it may be able to run across two phases.
We are not talking about silly mickey mouse motors here, we are talking about quality medium to heavy duty commercial/industrial kit.
Kendor, there is nothing special about the way in which Vent-axia manufacturers it heavy duty motors, all three phase motors will run on single phase if the windings are linked out correctly, that is a plain and simple fact.
I agree that a DEDICATED single phase motor with a single winding will never run of three phase in the normal way, although it may be able to run across two phases.
We are not talking about silly mickey mouse motors here, we are talking about quality medium to heavy duty commercial/industrial kit.
no they won't! Not without some method of creating a rotating magnetic field in the stator you keep mentioning Vent Axia but i say again that is a motor that has three or more windings and you wire it accordingly and there will be a method incorporated either inside the controller or the motor/housing that will make one of those windings a start winding when the fan is used on single phase the vent axia fan in my house has a start/boost position on the controller and a run position, without taking it apart this suggests that the start position incorporates a capacitor into one of the motor windings to put it out of phase with the other windings and if the controller is left in the start position then the motor is running as a capacitor start and run motor which is ok on the smaller fan motorsFWL_Engineer said:
when you switch the controller to the run position the capacitor is removed.
FWL Ive looked around and found a good site showing motor theory, have a looksee here chapter 4 particularly the sections on rotating magnetic fields.see this
I never said that! we were talking about 3 phase motors working on single phase which as explained in posts above doesn't work on a plain standard 3 phase motor.
Your comment above suggesting that a single phase motor might run across two phases, suggests to me that you might have been on the old firewater again
(unless you are referring to my post about 230v three phase systems and the motor is a 230v single phase motor)
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Big_Spark
On the single phase issue I was referring to a limited number of motors that are designed to run on single phase or at a push across two phases at 400V. I'll admit I have not seen one for a number of years, so it is possible they are no longer manufactured, but there was a time they were popular in certain industries.
Kendor, regarding the three phase to single phase motors, if it doesn't have a capacitor on it, it is a simple matter to add one, however these days it is also possible to add electronic phase adjusters..if your budget stretches to that of course, far far cheaper to add a cap.
BTW..I dod not mention the capacitor before for two reasons, 90% come with a cap fitted and as it is so easy to fit one, didn't see the point in stating the obvious. Apologies if this clouded the matter.
Kendor, regarding the three phase to single phase motors, if it doesn't have a capacitor on it, it is a simple matter to add one, however these days it is also possible to add electronic phase adjusters..if your budget stretches to that of course, far far cheaper to add a cap.
BTW..I dod not mention the capacitor before for two reasons, 90% come with a cap fitted and as it is so easy to fit one, didn't see the point in stating the obvious. Apologies if this clouded the matter.
Well now that all the fuss has died down, you can all enjoy yourselves reading about rotary convertors.
http://www.nycsubway.org/tech/power/rotary.html
http://www.nycsubway.org/tech/power/rotary.html
this was the point, adding a capacitor is modifying from the original argument
One thing though the motor would still have to have an auxillary winding(making it different from a standard three phase motor which has equal windings over the 3 phases) if you were to wire it up to work on single phase) in order to use the capacitor it is this specially wired winding that starts off the initial rotating field the capacitor having put it out of phase to the other windings.
Going back to the wiring up of the 3 phase motor to run it on single phase, how would you connect the capacitor in circuit to make the "standard three phase motor" run?
btw was the link helpful?
One thing though the motor would still have to have an auxillary winding(making it different from a standard three phase motor which has equal windings over the 3 phases) if you were to wire it up to work on single phase) in order to use the capacitor it is this specially wired winding that starts off the initial rotating field the capacitor having put it out of phase to the other windings.
Going back to the wiring up of the 3 phase motor to run it on single phase, how would you connect the capacitor in circuit to make the "standard three phase motor" run?
btw was the link helpful?
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Big_Spark
The simple way is to link two of the windings as one winding, then link the capacitor in series with the third winding, which will actually be in parallel to the Primary winding (The two linked together)
I would do a drawing, but simply can't be arsed, it's been a long day
I would do a drawing, but simply can't be arsed, it's been a long day
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Big_Spark
Stod said:
Stod, it was a insult because you could not be bothered to look at Vent-Axias website properly, and you had the cheek to state that I was wrong and talking bullshit (earlier post) when your not even a qualified electrician let alone an engineer..so yes I do find your post insulting. Your link may refer to a single phase version in isolation but if you had followed the link I posted then perhaps you would have learnt something instead of going off half-cocked.
FWL_Engineer said:The simple way is to link two of the windings as one winding, then link the capacitor in series with the third winding, which will actually be in parallel to the Primary winding (The two linked together)
I would do a drawing, but simply can't be ****, it's been a long day
in principle that way you have a main winding and a seperate winding in parallel with series cap but because of the nature of the 3 phase stator setup the windings will not be physically correct, for one thing the "aux" winding will not be at 90 degrees to the main winding as in a split phase motor, if you look at the site which i gave the link to earlier you'll see this is stated there.
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Stod
Quod erat demonstrandum, FWL.
(Latin & Welsh)
touché
(Latin & Welsh)
touché
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Big_Spark
kendor said:
Kendor, why on earth are you continuing to argue this point? You are wrong and I am right, this is not me being arrogant, this is me stating a fact known to anyone who works with large motors on a regular basis. I don't give a stuff that some site says the same as you, it is a simple unadulterated fact that 3 phase motors will work on single phase with the addition, if not supplied by the manufacturer, of a capacitor of the correct rating to induce a rotating magnetic field and the six winding ends are connected a such a way as to put the cap in series with one winding and the reamining two windings connected in parallel with this winding.
It is a FACT.
Incidently, I have looked at the site. Much of what they say is correct, but you can hardly use that as a good example of an informative site, this thread contains more information on 3 phase motors that the whole of chapter 4!!
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Stod
FWL_Engineer said:
Oh yes I did. It does not support what you say.
It gives three diagrams for connection to three phase supplies and three for connection to single phase supplies. Under each diagram there is a list of the fan model numbers to which the diagram applies.
All three single phase diagrams only list single phase fans. Similarly, all the three phase connection diagrams list only three phase fans.
If what you say is correct, I would have expected the list of connections to single phase supplies to include three phase fans. They do not.
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