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three phase static to rotary convertor

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  • three phase static to rotary convertor

    Hi I have a three phase from single static convertor professionaly made not home built.I asked this before but didn't get an answer that humble I could grasp. Anywaythe static convertor is 5.5 kw or 7.5 hp a good big one. I have been told it I first feed the wires into a three phase motor and then to my junction box to be taken onto the machines this will transform the static to rotary I think I was told this is basically correct, however what size motor smothing motor should I use a small one or as big as possible, I.e should it be the full 5.5kw to work or will anyone do as its just for smoothing the performance.I have a few new 3/4hp motors in three phase would they suffice Alistair I also have a large rotary convertor which I bought on Mark jones'es reccomendation it works good but a bit noisy as it has an inbuilt motor and I have housed it in an anti troom off our main central heating room so that I am not troubled by the constant din whilst I work regards Alistair excuse typing
    Please excuse my typing as I have a form of parkinsons disease

  • #2
    Hey I did warn you that the damn thing makes one hell of a row .

    It's like one of those fish tank pumps ..give it a kick and it will be quite for half an hour .then it starts again

    As regards your static Alistair ...I would leave it well alone and sell the thing.
    As you've already damaged the electrics of your lathe with the thing......experementing
    Once bitten twice shy ..etc ..think is the attitude you should take ..
    BTW did you phone GDR

    All the best..mark


    • #3
      Alistair-- I am afraid I was one of the folks who replied the first time. I apologize if I was not clear that time around.

      Most static converters are a relay and a starting capacitor. The relay is of a special type that just senses the voltage coming up in the "third leg" of that motor and then disconnects the capacitor from it (after it starts).

      To make this all work, that capacitor has to be correctly sized for the motor it will be starting. It is usually correct within some small range...maybe 3-5HP or 1-3 HP for example.

      If you wish to use the static to start an idler motor that will serve as a sort of three-phase generator, that should work, but you should pick an idler motor that is in the "rated" range of the static converter you have.

      I think I got too cought up the last time telling you how you could also add some balancing capacitors to your idler motor to make "better" three phase power etc.

      If what I wrote this time was still perceived as hogwash, write back and I would be happy to try it another way

      edit-- I went back and read some more. If you damaged something with the static converter, it could indeed be from trying to start something out of the specified range of the starter. Static converters also do not do well when other electronics are involved. A good, well balanced rotary would be better there.

      Good luck to you!
      Last edited by pcarpenter; 06-07-2006, 11:10 PM.
      Paul Carpenter
      Mapleton, IL


      • #4
        As mark said I blew up the static twice trying to run my lathe but after reading up on it I think that was because my lathe has variable speed.So it has blown again and I had to buy a timer for $50 since you were last here Mark also I know you warned me about the noise,but it is still a great rotary convertor and the way I have it configured up on top of the towels cupboard we discussed it makes no noise in the shop as I have dug through the wall well my neighbour did it actually and in return I wired up his workshop as he had it wired wrong and was let down by the electrician not turning up.I use the static for my sander sixteen inch with belt ,and my grinder, pillar drill ,etc etc all one at a time of coursein my woodshop works great but I was told by a friend it would work better without blowing anything.Iam convinced it won't do that again or should I sell it and buy a rotaryAlistair
        Please excuse my typing as I have a form of parkinsons disease


        • #5
          How many rotarys do you want ...
          Do you relise, with the one you have already you can run many machine tools all at the same time ..up to 5.5 hp total.

          and how many Alistairs are there ..........mmmmmmmmmmmmm ONE.

          So just extend the wiring ..more juction boxes, multiplug boxes, etc.

          all the best.......mark


          • #6
            Mark as you are well aware I have two workshops not one! so one in each will be required as I cannot run it satisfactorily from one place it would mean wires everywhere and running all the way down to one shop to start and then again to stop it when it was not required. This is a two convertor set up definitely.I also have to vfd invertors one for my mill and one for my woodlathe as I need variable speed for those and the static and rotary don't provide that.P.c sorry I did not mean to imply any hogwash just that I am not very conversent with these I have read a lot but praciced few times and need your type of expertise to help me. The problem was not that my static convertor was too small or not matched in fact it had more than enough power the lathe it blew both itself up on and the lathe itself was three horse power and the static was 7.5 hp so plenty of power but this would not work the lathe motor heated up and would not start. Eventually I got it started as soon as I tried to run it or alter speed it cut out immediately.The problem is as I read later static convertors don't work well with vsl lathes i.e variable speed lathes as all I do to alter the speed on my lathe is push two knobs downward one says increase and the other says decrease speed.The part that blew up in the lathe was the transformer from 440 to 110 for the starting and the lamp which needs to go down to 110 I now have removed this and have a seperate 110 supply from 220 which I wire seperately and this works fine so far no probs since I bought the rotary with Marks help as he bought one from the same company and was able to recommend it to me it now runs all my 3 phase stuff in my metal shop but as said I have a seperate 3 phase static in my wood shop made bytranswave.Hope this is clear regards every one and thanks excuse typing again Alistair
            Please excuse my typing as I have a form of parkinsons disease


            • #7
              well the only way to do it is thus
              this will make your tranwave idiot proof and turn it into a rotary .

              you got to hook up a 5hp 3 phase idle motor to your transwave somehow and come off the motor with your power requirements ..i don't know .

              AT a guess i would say you just come off the three wires going to the motor

              please ..usa guys keep out of this .because we have only 1 live for single phase not two..

              so the advice on how to do this should be coming off the English guys.......its probably a very simple hook up .....only Ive NOT done it i don't know how.



              All the best..mark


              • #8
                if I run a 5 hp motor will I not have taken up the power of the static convertor before it hits any machine I know the motor is only idling so maybe it wont drain the juice.And getting a 5hp 3ph motor will not be easy but I will try as far as the 3phase electric company I willcontact them next week as we have the builders in and the house is in turmoil regards Alistair
                Please excuse my typing as I have a form of parkinsons disease


                • #9
                  I have found that you can start up to (in your case) five hp from a five hp rpc. After one motor (in addition to the rpc) you can start and run more motors up to three times the rated rpc hp provided your source power is adequate. More motors running will have a smoothing effect on the three phase power.
                  my two cents worth
                  Herm Williams


                  • #10
                    My static convertor is 5.5kw or 7.5hpAlistair
                    Please excuse my typing as I have a form of parkinsons disease