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  1. #46
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    Hi Dean,

    I think I have a solution that will work with what you currently have. That picture of the terminal cover jogged a few brain cells...

    You have a Delta, DoubleY Dahlander. Which can be converted to 240V 3Ph double delta. ( some other Dahlander configurations require rewinding the motor! ) by Linking U1 to U2, V1 to V2 and W1 to W2.

    AM_Dahlander.jpg

    You can then run at 4 pole (1440 rpm) fulll power, ( or as much as your VFD can deliver ).

    What you will find is that even though it's full load current is going to be 25A or so, most of the time in normal operation you will be drawing a lot less than that.

    So If you program the current limit on the VFD to suit your power cabling, I'd guess 15A? then you'll get 4.5-5 hp, see how that goes with the machining you'll be doing before you go looking for a bigger VFD.


    Regards
    Ray

  2. #47
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    Gallegos.

    I would say the vfd you have will be fine if you are happy to limit the power and have a longish start ramp time. I would definitely recommend an ammeter on the supply to the vfd so you know whats happening... I have a combined ammeter voltmeter that was less than 10 bucks on ebay but seems to work great.

    If I find the VFD too limiting then I can upgrade it later. I can always use this one on the shaper.

    An ammeter is a great idea.

    Is the motor you converted for your mill similar to mine or a single speed motor? You are saying to cut at 2U, 2V, 2W?

    Motor Winding Circuit.jpg

    I would be interested in looking at books on this subject. Thanks.

    BaronJ.

    This motor is original for this lathe. 2 speeds to get full range of speeds for the lathe. Slow speed up to 1000rpm and high up to 2000rpm. Saves doubling up on the gearing.

    BobL was only looking for a picture of my cover. Waiting very patiently I might add.


    Keith_W.

    PDF is very useful.


    PDW.

    I know a bloke in Donald that might be able to help you out if you want to go that far. PM me for his details, he looks after the electrical stuff etc for a couple factories and I'm pretty sure he has some motors lying around as spares, might have a 5 HP unit. Very nice man to deal with and a wealth of information. Also I may be interested in buying that motor off of you if you can't use it yourself......
    Thanks. I will keep this in mind although if you read I have discarded this motor give me a reminder. In that case I would be interested in this bloke in Donald and his help.


    Dean

  3. #48
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    Ray.

    I will do this first. Thanks for this info. I have decided to try and jog my brain cells and read up on these motor some more if I get some books off Gallegos or find some myself.

    A quick check with an online calculator tells me that 6mm2 cable is capable of up to 41A. 30deg average temp, 45m run, 5% loss. I think I will put in a 32A breaker. That should cover it.

    Dean

  4. #49
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    Aug 2009
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    Quindanning, WA
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    Quote Originally Posted by Oldneweng View Post
    Gallegos.




    If I find the VFD too limiting then I can upgrade it later. I can always use this one on the shaper.

    An ammeter is a great idea.

    Is the motor you converted for your mill similar to mine or a single speed motor? You are saying to cut at 2U, 2V, 2W?

    Motor Winding Circuit.jpg

    I would be interested in looking at books on this subject. Thanks.


    Dean
    Yeah... If you only have 6 leads coming from the motor into the terminal box you will find one of the leads will go to each of these points Inside the motor and split. If you are going to open it up and modify it i would put in individual leads for each coil group so you have 12 leads to the terminal box. If you do that you will be able to choose to have it as either 4 or 8 poles by changing polarity on 3 of the coil groups. The motor will be 7.5 hp either way once its parallel delta.

    Whats the vfd current rating? I would try to limit current on the single phase side to the rating so the bridge rectifier isn' t stressed.

    My mill motor was a 4 pole single speed but i also did the same to the 3 hp power feed motor and i reckon yours could potentially be easier because the windings are already split.

    I will have a look for the books.

  5. #50
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    Quote Originally Posted by gallegos View Post
    Yeah... If you only have 6 leads coming from the motor into the terminal box you will find one of the leads will go to each of these points Inside the motor and split. If you are going to open it up and modify it i would put in individual leads for each coil group so you have 12 leads to the terminal box. If you do that you will be able to choose to have it as either 4 or 8 poles by changing polarity on 3 of the coil groups. The motor will be 7.5 hp either way once its parallel delta.

    Whats the vfd current rating? I would try to limit current on the single phase side to the rating so the bridge rectifier isn' t stressed.

    My mill motor was a 4 pole single speed but i also did the same to the 3 hp power feed motor and i reckon yours could potentially be easier because the windings are already split.

    I will have a look for the books.
    VFD current rating is 23A I think. This is interesting because I cannot find any model number or size on the unit at all. The instruction book covers all models but it does not cover single phase any higher than 2.2kW. I am hoping mine was too new to make it in.

    Dean

  6. #51
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    I thought I would have a quick look on EvilBay as It is a long time since I have checked VFD's. The following is a link to a 5.5kW (7HP) single to 3 ph which has a remote control unit supplied with a 1m cable. It seems to be a standard network cable so can be changed for any length required. This VFD is $825 +$25.

    Dean

  7. #52
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    Quote Originally Posted by A Duke View Post
    As the disclaimer suggests get someone in who knows.


    But this rough sketch will show roughly what the difference is.
    Attachment 298573
    Excuse how rough my sketches are. The easiest way to see what you have is to do a continuity test on the 6 connections. A normal 3 phase will give you a reading between A1 an A2, B1 and B2, C1 and C2 and nothing between them (A,B and C ) the 2 speed motor ( Phase shift ) will give you readings (different values) between all 6 connections.
    I hope this helps but if it just adds to the confusion I hope it does enough to convince you to call in the experts.
    Regards
    Big mistake! What I labelled low speed should be high speed. Senior's moment, it's over 30 years since I worked on one of those. You will notice although the configuration of the later drawings is a little bit different the connections are the same.
    Regards
    Hugh

    Enough is enough, more than enough is too much.

  8. #53
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    Quote Originally Posted by A Duke View Post
    Big mistake! What I labelled low speed should be high speed. Senior's moment, it's over 30 years since I worked on one of those. You will notice although the configuration of the later drawings is a little bit different the connections are the same.
    Regards
    That's ok Hugh. That part of your drawing (2 speed) was the same as the one linked (PM) in a previous thread by Simon except the coil layout was different. Same end result. Same connections. I compared them and used the one from PM as it was clearer. I have another confession to make. I looked for the same diagram on Google as your single speed one so I could see it clearer. Thanks for the diagrams as they were helpful to point me to others.

    Dean

  9. #54
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  10. #55
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    That's even better. I only had a quick look. For that price I could build a remote control unit I think. How big is the hole in the transformer for the meter. I guess it is big enough but I could not see it mentioned in the description.

    Dean
    Last edited by Oldneweng; 28th Dec 2013 at 05:35 PM. Reason: Notebook Keyboard Playing Up

  11. #56
    BobL is offline Member: Blue and white apron brigade
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    I've used 4 of those AC ammeters.
    I have two extension cords with them built in and the others are on machines.
    This one is on my DC

  12. #57
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    Quote Originally Posted by Oldneweng View Post
    A 3ph generator would be a tiny fraction of that cost tho!

    Dean
    If you are ever tempted or have the opportunity to use three phase from a generator make sure everything is wired correctly. I had a customer who did not wire things correctly and it cost him a motor rewind. Apparently just plugging it in can lead to problems as his pocket found out.
    CHRIS

  13. #58
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    Quote Originally Posted by Chris Parks View Post
    If you are ever tempted or have the opportunity to use three phase from a generator make sure everything is wired correctly. I had a customer who did not wire things correctly and it cost him a motor rewind. Apparently just plugging it in can lead to problems as his pocket found out.
    Now that would be a job for the experts. We had a pump at work that was attached to a frame with wheels, made by an apprentice we called psycho and so the pump was named psycho. It was a slow pump until some years later it was discovered that the sparky had connected it to run in reverse. It gets used more now. We use pumps that we push to the job.

    Dean

  14. #59
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    Quote Originally Posted by Oldneweng View Post
    Now that would be a job for the experts. We had a pump at work that was attached to a frame with wheels, made by an apprentice we called psycho and so the pump was named psycho. It was a slow pump until some years later it was discovered that the sparky had connected it to run in reverse. It gets used more now. We use pumps that we push to the job.

    Dean
    3phase things that get wheeled to the job need to have there direction checked every time they are plugged in, as the plug socket could be wired opposite to the last one. The sparky could have had it right where he wired it up.
    Regards
    Hugh

    Enough is enough, more than enough is too much.

  15. #60
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    Quote Originally Posted by Oldneweng View Post
    That's even better. I only had a quick look. For that price I could build a remote control unit I think. How big is the hole in the transformer for the meter. I guess it is big enough but I could not see it mentioned in the description.

    Dean
    Cant remember the size of the hole in the ammeter... They used to be slightly different with a smaller toroid attached to the back but it still it fit a 6mm2 cable comfortably. You only need to run one wire through the toroid, dont think it matters if its active or neutral.

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