3 phase motor connection

grousedogtom

Hi,i have been asked to connect a 3 phase motor on a pillar drill, now who ever disconneted it before it was sent for repair never marked anything and removed all the links so i am now left with 6 connection points and no links between any of them, is there a means of telling what to link and where to connect my 3 phases using an omh meter , if so could someone describe this method ps no wiring diagram available.

ntpm

grousedogtom wrote: »

Hi,i have been asked to connect a 3 phase motor on a pillar drill, now who ever disconneted it before it was sent for repair never marked anything and removed all the links so i am now left with 6 connection points and no links between any of them, is there a means of telling what to link and where to connect my 3 phases using an omh meter , if so could someone describe this method ps no wiring diagram available.

http://www.johnson-pump.com/Horticulture/quickstart-motor.htm


Try this link.

First trace each winding. Look for markings U1 to U2,V1 to V2,W1 to W2 or use meter.
If you have 3 cables at motor you will have one contactor and will have to choose place links in iether Star or Delta Layout.
This depends on starting amps and possible speed/ torch required etc.. Look a contactors or overload details. Hard to advise on.

if you have six cabls at motor e then you have a Star-Delta Contactors which change over the configurations of the windingsn for you.

Hope it helps.:)

Bruthal

grousedogtom wrote: »

Hi,i have been asked to connect a 3 phase motor on a pillar drill, now who ever disconneted it before it was sent for repair never marked anything and removed all the links so i am now left with 6 connection points and no links between any of them, is there a means of telling what to link and where to connect my 3 phases using an omh meter , if so could someone describe this method ps no wiring diagram available.

Do you still have the original cable end that goes into the motor, does it have 3 wires in it (not including earth)? There should be also a rating plate on the side of the drill motor telling you the motor power in watts or HP in either star or delta. If the cable has 3 wires its likely its connected in delta with the 3 links across the terminals like the second diagram in the link in ntpm`s reply. If it has 6 wires then there would of been no links and you have to conect 3 to one set of terminals and 3 to the other. If this is the case then let us know and i will try to assist how to connect. Did the cable end have any labels? U1,V1,W1 U2, V2, W2 are the winding ends usually numbered in the motor connection box.

If it is 6 wires it will be connected as in the 3rd diagram of ntpm`s reply. Its a star delta starter, its straight forward enough but might look a bit confusing. Let us know and we can try advise according to number of cores in the cable you have to re connect.

If you look at the star delta starter you notice D1 and D2 will be closed when motor is running fully in delta. The 2 wires into U1-W2, and into V1-U2 and into W1-V2 each form a loop through the 2 contactors so they are each connected to the same phase as if the 3 links were on the motor terminals, this is how you would connect if its 6 wires, if you push in the main and delta contactors manually, you will find the 3 pairs of wires to connect directly across the terminals from each other using a continuity tester. If drill goes backwards then you have to swap 2 pairs around, or swap just 2 phases into the star delta starter.

Manual pushing in of contactors may not be possible though. Let us know is it 3 or 6 wires first anyway.

grousedogtom

Thanks all for above help , the motor has no cables in connection box just 6 poles with a nut and washer on each for connection these are not marked either, I presume these are the 3 sets of windings a pair for each. I am almost sure the motor was originally connected in either star or delta but not star delta as there is links with the motor which were used when last connected. can i use an omh meter to find the 3 pairs of windings and then connect in star or delta and if so which would be most usual for a small motor, i think its only 3/4 HP.

DublinDilbert

I'd connect it in star and see how it runs. This will minimise the voltage on each winding.

Is there a 3 phase contactor controlled by a start/stop circuit?

You should be able to identify the three windings with a meter. I'm open to correction here, but the polarity of thew windings is impotant. I'd connect as star and see how it runs. If there's any roughness swap the polarity of one phase, see if it makes a difference, keep going till it runs smooth.

Bruthal

DublinDilbert wrote: »

I'd connect it in star and see how it runs. This will minimise the voltage on each winding.

Is there a 3 phase contactor controlled by a start/stop circuit?

You should be able to identify the three windings with a meter. I'm open to correction here, but the polarity of thew windings is impotant. I'd connect as star and see how it runs. If there's any roughness swap the polarity of one phase, see if it makes a difference, keep going till it runs smooth.

There should be no need to identify the winding ends as i think 6 terminals would show us its a standard U1 V1 W1-W2 U2 V2 setup, and without any doubt only the standard setup allows the star or delta configuration using the links. If there are 3 link connectors then it was a delta setup, a star setup with links only requires 2 links, but that would not be a definitive method to sort it, and the windings will have no polarity, but i would of thought the drill had some sort of in-built control to switch on and off the motor at least rather than just a 3 phase supply straight from an isolator on the wall into the drill motor and as such should have a flex somewhere to connect into motor.

But im open to correction also

Bruthal

grousedogtom wrote: »

Thanks all for above help , the motor has no cables in connection box just 6 poles with a nut and washer on each for connection these are not marked either, I presume these are the 3 sets of windings a pair for each. I am almost sure the motor was originally connected in either star or delta but not star delta as there is links with the motor which were used when last connected. can i use an omh meter to find the 3 pairs of windings and then connect in star or delta and if so which would be most usual for a small motor, i think its only 3/4 HP.

How many links are there, if there are only 2 then it was star probably, but check the motor rating plate if there is one, and see does it tell you the power ratings in both star and delta and/or the winding voltage ratings.

For a 3/4 HP motor it was probably delta direct on which needs 3 links. If the windings are rated 400v then connect the motor in delta, if 220-230v then it would have to be connected in star.

grousedogtom

3 links robbie so i,ll connect delta direct, many thanks for all the above help , great site for useful info.

Bruthal

grousedogtom wrote: »

3 links robbie so i,ll connect delta direct, many thanks for all the above help , great site for useful info.

Just have a look for motor rating plate though, as in star only 2 links are needed but we would double one link up so as to still have the 3 links in the terminal box and as such, 3 links would`t certainly mean it was delta, but it probably was. In delta the windings each have 400v across them but in star its only 230v across them. If the windings are only 230v windings then it would have to be connected in star to a 400v 3 phase supply

2011

+1 Robbie

I'm open to correction here, but the polarity of thew windings is impotant

This is not correct. Once the motor is rotating in the correct direction the polarity is not an issue.

ll connect delta direct

If unsure connect in star first. Then it will not draw too much current (only too little if connected incorrectly). The person that uses the drill will know if it is under powered the moment it is switched on.

Bruthal

2011 wrote: »

If unsure connect in star first. Then it will not draw too much current (only too little if connected incorrectly). The person that uses the drill will know if it is under powered the moment it is switched on.

Good advice

DublinDilbert

2011 wrote: »

+m

This is not correct. Once the motor is rotating in the correct direction the polarity is not an issue.

You don't understand what I mean by polarity. I know swapping any two windings will reverse the motor. I meant each individual winding will have a polarity too, based on how it is wound on the stator

Bruthal

DublinDilbert wrote: »

You don't understand what I mean by polarity. I know swapping any two windings will reverse the motor. I meant each individual winding will have a polarity too, based on how it is wound on the stator

not really, each winding would be matched in its winding direction/polarity

Bruthal

DublinDilbert wrote: »

You don't understand what I mean by polarity. I know swapping any two windings will reverse the motor. I meant each individual winding will have a polarity too, based on how it is wound on the stator

It would actually be a considderation when connecting the 6 wires from a star delta starter, the 3 wires from the star/delta contactor would have to be connected to the 3 winding ends on the same side.

M cebee

DublinDilbert wrote: »

You don't understand what I mean by polarity. I know swapping any two windings will reverse the motor. I meant each individual winding will have a polarity too, based on how it is wound on the stator

i think you're right

the start/finish of the windings has to be identified afaik

if they're not known

Bruthal

M cebee wrote: »

i think you're right

the start/finish of the windings has to be identified afaik

if they're not known

Not if its a standard 3 phase motor that had link bars in it. On one side you have U1 V1 W1, and facing them you have
W2 U2 V2

So the 3 bars across W2-U2-V2 or across U1-V1_W1 gives star.
From U1-W2 and V1-U2 and W1-V2 gives delta. Which side is which does`t matter, but the windings will be staggered from one set of terminals to the other in any motor that had links.

For a star delta starter with 6 wires the 3 from the main contactor go on one set, and facing them the 3 from the star/delta contactors go on opposite set, phases on both sets match direct across as if the link bars were straight across. Which side has which set of 3 wires from main or star/delta contactors makes no difference at all.

Having said that i would do a quick test if it was first time i had seen the said motor, But thats not really a polarity test.

If winding ends were direct across from each other then the link bars cant work for delta, they would for star however.
I never seen a motor with terminals except as above. Has anyone else?

M cebee

ya he's ok if the windings are connected into the block


and the start finish face each other

Bruthal

M cebee wrote: »

ya he's ok if the windings are connected into the block


and the start finish face each other

The start finish of windings should`t face each other in a standard 3 phase motor with the 6 terminals available, otherwise putting the 3 links across for delta would just be connectiong the ends of the same windings together. If you draw out the way the 6 terminals are and see the way the winding ends are stepped over on other set, then draw in the 3 links for delta, you can see how it forms the delta triangle of windings.

Im sure there may be motors with the windings facing each other, but then the links could`t work for a delta direct online connection.

2011

You don't understand what I mean by polarity. I know swapping any two windings will reverse the motor. I meant each individual winding will have a polarity too, based on how it is wound on the stator

I know what you mean (I think!)

For example: You mean if U1 is connected where U2 should be and U2 is connected where U1 should be? This will make no difference once the motor direction is correct.

2011

Not if its a standard 3 phase motor that had link bars in it. On one side you have U1 V1 W1, and facing them you have
W2 U2 V2

So the 3 bars across W2-U2-V2 or across U1-V1_W1 gives star.
From U1-W2 and V1-U2 and W1-V2 gives delta. Which side is which does`t matter, but the windings will be staggered from one set of terminals to the other in any motor that had links.

Exactly!

Bruthal

2011 wrote: »

I know what you mean (I think!)

For example: You mean if U1 is connected where U2 should be and U2 is connected where U1 should be? This will make no difference once the motor direction is correct.

That actually would make a difference. But that can only be wrong if the winding ends were swapped coming out of motor itself.

But its sort of a non issue that, as the motor is as it is. And there is no polarity test will tell us which actual way the winding is from one terminal to other. Its getting confusing alright

2011

That actually would make a difference.

I don't think so. What would that difference be?

IMHO the difference would be that the motor would run in the other direction, just like swapping 2 phases.

What difference do you think it would make?

But that can only be wrong if the winding ends were swapped coming out of motor itself.

Or if all 6 winding ends were all coming out at one point unmarked and you could not tell which end you were looking at.

Bruthal

2011 wrote: »

I don't think so. What would that difference be?

IMHO the difference would be that the motor would run in the other direction, just like swapping 2 phases.

What difference do you think it would make?


Or if all 6 winding ends were all coming out at one point unmarked and you could not tell which end you were looking at.

Ok well in a correct connected motor U1 V1 W1 And W2 U2 V2.
Delta would have Brown -U1 Black V1 Grey W1
And Brown W2 Black U2 Grey V2
Now swap winding U1 U2 ends around, It now has U1 connected to Black instead of brown, and the other end U2 connected to brown instead of black so that one windings polarity has been swapped with reference to the other 2.

Thats my view of it anyway, im not saying beyond all doubt its right, but i cant see it working with one winding reversed with respect to the other 2.
Or how it can happen with a 3 wire supply and 3 links.

If all 6 ends are out at one point? If its 2 rows of 3 i dont see the need to really know anything except that we have a staggered setup.

You could be right though,
In actual fact thinking about it now id say you are right, which even more shows not much testing is needed once its shown to be staggered ends.

Bruthal

2011 wrote: »

Or if all 6 winding ends were all coming out at one point unmarked and you could not tell which end you were looking at.

If its 6 wires from star delta starter, once 3 wires from one contactor are kept to one set of 3 termonals and the 3 from the other are onto the other 3 opposite terminals, there would`t be any issue with any of it once the windings are shown to be staggered.

In this case it looks like it was 3 wires DOL with links, so again winding polarity is not an issue at all,

M cebee

robbie7730 wrote: »

That actually would make a difference. But that can only be wrong if the winding ends were swapped coming out of motor itself.

But its sort of a non issue that, as the motor is as it is. And there is no polarity test will tell us which actual way the winding is from one terminal to other. Its getting confusing alright

afaik the start/finish orientation on the windings makes a difference-if they weren't marked

the motor will not run properly


this is not the same as reversing a phase for direction

i will post a link later when i find one


it's only an issue if the 6 wires are hanging out of the motor

this is what dublindilbert is referring to as 'polarity'

Bruthal

2011 wrote: »

IMHO the difference would be that the motor would run in the other direction, just like swapping 2 phases.

What difference do you think it would make?
.

I would have to say though i am not absolutely certain it does make no difference, as we are in effect reversing one windings direction completely, it would be like reversing the direction the winding is wound in compared to the other 2, i would just say im not sure on it.

Bruthal

M cebee wrote: »

afaik the start/finish orientation on the windings makes a difference-if they weren't marked

the motor will not run properly


this is not the same as reversing a phase for direction

i will post a link later when i find one


it's only an issue if the 6 wires are hanging out of the motor

this is what dublindilbert is referring to as 'polarity'

Yea im not certiain of it myself, i remember drawing this out before and from that i believed that reversing a windings direction compared to other 2 was not the same as reversing 2 phases. Reversing 2 phases always actually reverses the orientation of 2 windings at the same time. which in effect changes the position of 2 windings around with each other, where as reversing a single windings direction does not achieve this. My thought before on it was motor would not run right.

And yes if 6 wires were removed from their terminals then thats where theres a problem. Usually the wire ends have markers though. but hard to read if at all.

Bruthal

3 windings in a 3 phase motor. A,B,C

Winding A peaks first, then B then C
Swap 2 phases and so winding A and B together have now swapped direction because in star swapping 2 phases swaps 2 windings, in delta the same is true as each phase supplies 2 winding ends. Now its B,A,C direction.

If just swap winding A polarity, then winding A will still peak then B then C, but winding A magnetic field flows in opposite direction.
This was my conclusion a few years ago when it came up in a job, that the motor would not run.

Again i dont say this is certain, but in my mind it seems reversing a single windings polarity is not the same as swapping 2 phases.

Bruthal

DublinDilbert wrote: »

I'd connect it in star and see how it runs. This will minimise the voltage on each winding.

Is there a 3 phase contactor controlled by a start/stop circuit?

You should be able to identify the three windings with a meter. I'm open to correction here, but the polarity of thew windings is impotant. I'd connect as star and see how it runs. If there's any roughness swap the polarity of one phase, see if it makes a difference, keep going till it runs smooth.

If you meant polarity of windings with respect to each other then id have to say you could be right, i was assuming all along that the 6 winding ends were still connected to their terminals, if they were not then it would be an issue i would say, that would be interesting, what test could be used to sort that out without running.
With polarity of one winding wrong compared to others i think motor wont run at all but would make plenty of noise.

As i said though, if the 6 ends were still on their proper terminals, none of this is an issue.

grousedogtom

Ok i connected in delta first but switched off immediately as each phase was puling 8 amps, i then switched to star and all perfect, thanks for all replys

M cebee

robbie7730 wrote: »

If you meant polarity of windings with respect to each other then id have to say you could be right, i was assuming all along that the 6 winding ends were still connected to their terminals, if they were not then it would be an issue i would say, that would be interesting, what test could be used to sort that out without running.
With polarity of one winding wrong compared to others i think motor wont run at all but would make plenty of noise.

As i said though, if the 6 ends were still on their proper terminals, none of this is an issue.

there's a few ways of doing it with 12v ac supply etc