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11th Aug 2010, 09:51 PM #1I break stuff...
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Have I found the star point of this motor?
Just after opinions from those who've dug the star point out of motors before - does this (red arrow) look like a star point normally does? Definitely seems to be 3 wires going into one piece of insulation sheath...
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11th Aug 2010, 10:22 PM #2
Hi Jekyll & Hyde,
There should be 3 terminals marked U V W at the mains entry point, get a multimeter and buzz (continuity test) between each of those terminals and the star point.
I assume you want to convert to delta? for 240v 3 phase?
Mark the terminals at the mains entry point U1 V1 W1, desolder the wires at the star point and run wires from there to the mains entry. Buzz them and identify which ones are U V W coils, and label them U2 V2 W2.
Arrange the wires at the mains entry point as follows..
U1 <--- link ----> W2
V1 <--- link ----> U2
W1 <--- link ----> V2
Now it's wired delta...
Alternatively, take it to a motor rewinding place and they will do the whole thing for you, if it's a suitable motor it 's a 10 minute job, also they can re-lacquer the terminations and test it for you.
Regards
Ray
PS... Of course the disclaimer above applies to my advice as well ...
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11th Aug 2010, 10:32 PM #3I break stuff...
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Hi Ray,
Unfortunately the wires coming into the motor just connect straight to the windings, but thats fine, I can mark them and then work out the windings with a bit of head scratching, thinking and possibly a little swearing. The little description you've given there is definitely the clearest I've found so far too, so thanks very much for taking the time to write it down.
The thing I'm not sure about though (and the reason for this thread), is whether this motor is actually wired star or not. The motor plate only says 415v, no mention anywhere of it being star or delta wound. I've made an assumption based on the fact its only a little 2hp motor that it would be star, and now that I have the cover off, the point I have arrowed definitely looks like I imagine a star point should.
It just seems way too convenient that its right at the end of the motor where I can access it without even taking the motor off the machine, so I was hoping someone would look and confirm that it looks like a star should, before I went and hacked into the insulation and started adding wires in...
Cheers, Ben.
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11th Aug 2010, 10:46 PM #4
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12th Aug 2010, 08:56 AM #5Most Valued Member
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what size motor is it?
My understanding is that most smaller 3ph motors are wired standard for delta?
it should have 240/415v and may also show delta and Y symbol on the name plate...if its got thia then it can be configured externally and no need to go into the stator
do you know how to check with a resistance meter?
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12th Aug 2010, 08:41 PM #6I break stuff...
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12th Aug 2010, 09:37 PM #7
J&H, how many wires are there in the terminal box? Coming from the motor windings that is. A star connected motor will have only 3. Motors that have 6 seperate wires coming from the motor can be connected either star or delta using bridging pieces in the terminal box. The area you have highlighted may be the star point or it could be a connection point for one of the winding tails. If you are unsure, contact a motor repair/rewind business and get a quote on how much it would cost to do it for you. I don't think it would be too much.
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12th Aug 2010, 10:24 PM #8I break stuff...
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ATTENTION:
With thanks to all the well meaning replies, HOWEVER. I am well aware of the fact that having 6 terminals in my terminal box would allow me to very easily wire this motor into delta, and if that were the case this thread would NOT exist at all. I am not asking how to identify a dual voltage motor, this is NOT one. It has the 3 incoming power wires soldered straight to the 3 wires coming out from the windings.
Which is why I have removed the back of the motor, so that I can identify the star point, seperate it, bring three wires out from there, and create the 6 terminals in the terminal box.
All I was after was, as asked for the in the first post, thoughts from someone who has done this modification in the past, on whether they agreed with me that what I have arrowed in the picture attached to the first post, is likely to be the star point. And the main reason for asking that, is that I am only 95% sure that the motor is even star wound, as it does NOT specify on the motor plate.
Thank you all. And incidentally, if a moderator is reading this, feel free to delete the entire thread, unless you feel it adds useful information for someone. I was hoping that it might help others in the future identify the star points of their motors, this seems unlikely at this stage.
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12th Aug 2010, 10:58 PM #9
ATTENTION The fact that you do not know that the motor is star wound,
even though I provided this information in my post.
If there are only 3 wires coming out of the terminal box then the motor can ONLY be star wound.
Take it to someone who knows what they are doing.
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12th Aug 2010, 11:25 PM #10I break stuff...
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Really. You're going to unequivocally say that? What stops a motor manufacturer from connecting the windings internally however they feel? Its entirely possible for me to reconnect the windings to delta, and still only have 3 wires coming out to the terminal box, so why is it impossible for the motor to be manufactured that way? Its assumptions like that which make an ass out of u and me, and have caught me before now (different application, same principle).
Right back at you buddy, read my previous replies on this topic, and you will realise you didn't need to reintroduce the wonderful new information about there being 6 terminals in the terminal box - I've already told two other people that the power coming in is connected directly to the windings.
Not exactly relevant to the original question either, is it? For all you knew, I might have just been having a look to see physically how all the windings actually join together out of pure curiousity.
For the sake of example, lets pretend I've run out of petrol in my car. Its spluttered to a stop, the tank is bone dry, its out. I come and ask you if you have any petrol I could borrow/buy. Do you start looking for the jerrycan, or do you ask me if I've tried turning the ignition key?