Announcement

Collapse
No announcement yet.

Running VFD from step-up transformer

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Running VFD from step-up transformer

    Alright, heres the deal, i just moved into a new house and im getting my new shop space set up. My surface grinder has a 3-phase motor that I run off of a VFD that takes 220v input. New shop space has no 220v outlet.

    Now, the smart solution here is to run a new 220v circuit, but that ones tabled for now. Old electrical system, panel needs to be upgraded, wiring needs to be sorted out, yadda yadda yadda, point is running a new circuit isnt an option at the moment so i need something as a stop-gap. So, step-up transformer, something that can take 120v in and pipe out 220v, something like this, then use that to send power to the VFD. Got the wattage i need for the VFD, breaker can handle the current that it would draw, but im worried about possibly harming the VFD. Far as i know, 220v60hz is the same no matter what it comes from, but i figured id ask the hivemind

  • #2
    As long as the transformer is powerful enough, the VFD does't care.
    Helder Ferreira
    Setubal, Portugal

    Comment


    • #3
      Should be no problem at all. 2000 watts would be about 17 amps at 120 VAC, and should be enough for a 2 HP VFD and motor.
      http://pauleschoen.com/pix/PM08_P76_P54.png
      Paul , P S Technology, Inc. and MrTibbs
      USA Maryland 21030

      Comment


      • #4
        you can get a suitable vfd for a similar price.

        Comment


        • #5
          How does the transformer at the pole
          not harm your VFD ? ? ?

          -Doozer
          DZER

          Comment


          • #6
            For smaller motor sizes, they make affordable VFD's that take in 120 and put out 240. Teco and TD are two that do.

            Comment


            • #7
              Your thought is correct, "220V" 60Hz is the same no matter the source.

              So what power motor do you need to run?

              The issue with a transformer of that sort is if it is too small, there may be too much voltage drop in it, and in some cases, a "compensated" transformer may "fix" the voltage drop by increasing the no-load voltage in order that the drop should bring it to the correct voltage. VFDs do not like excessive voltage.

              With a reasonable sized transformer for the load, that should not be an issue.

              The transformer you linked to is more "fancy" than you would need, by far. But it is cheaper than many alternatives. The question is whether it is what it claims to be. The makers cannot even SPELL "transformer" correctly...... the picture shows the front labeled "trnasformer"

              An alternative is a VFD that takes in 120V and outputs 240V. They exist, and are available up to 1 HP.
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #8
                When using a step-up step-down transformer one thing to remember is to re-reference the earth GND.
                This entails selecting one of the output terminals as a neutral, and this is where the system earth is connected to, the two conductors from this single terminal is then the Earth, the other the current carrying neutral.
                (ref NFPA79).
                One source of a transformer is any local electrical supplier.
                BTW, N.A. is pretty much 120v/240vac standard.
                Max.

                Comment


                • #9
                  Originally posted by RB211 View Post
                  For smaller motor sizes, they make affordable VFD's that take in 120 and put out 240. Teco and TD are two that do.
                  I did consider that, but the problem I ran into was cost. The 1hp 110 input VFDs that I could find with a quick search were up in the $200 range, which isn't horrible but if I can get the same end result by using the drive I have with a $100 transformer, well, that's $100 I can use on other stuff. I'll have to do some more looking into alternate VFDs, if I can find on in the $100-150 range I'll probably go that route

                  Comment


                  • #10
                    I run my 600 volt Bridgeport from 220V single phase stepped up to 600V and fed to my VFD. No issues as long as the transformer is big enough. Absolute minimum transformer is 1kw per motor horsepower connected and preferrably 1.5kw. Technically 747 watts (.747kw) equals 1 hp but somewhat bigger is only common sense.

                    Comment


                    • #11
                      That thing weighs 15 lbs only- doesn't seem like enough iron to be rated at 2000 watts. Makes me wonder if it's the real deal-
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

                      Comment


                      • #12
                        Do you have 2 or more separate 110 circuits? Jump them together

                        Comment


                        • #13
                          Originally posted by no704 View Post
                          Do you have 2 or more separate 110 circuits? Jump them together
                          While that "can" result in 220V, it is very much not recommended, and is against every electrical code around.
                          1601

                          Keep eye on ball.
                          Hashim Khan

                          Comment


                          • #14
                            Another thing to keep in mind is the actual ratings of the converter. I looked around a bit and one VERY important specification was the "duty cycle" or how long it can supply the power before overheat or failure. Many converters I saw online were only rated for 30 minutes at full rating and the continuous rating was around 50%. In any case, one very telling specification actually has nothing to do with electricity. It is the weight of the unit. In basic converters it takes IRON to make a high power transformer. After many years in the electric control industry, I have NEVER seen a 20 pound transformer that can provide 2000 watts for any length of time. On the other hand, Amazon has an excellent return policy. Get one that seems the best and run it hard as soon as you get it. If it smokes, send it back at Amazons expense!!!
                            Robin

                            Happily working on my second million Gave up on the first

                            Comment


                            • #15
                              If the two 115 Volt circuits are already in ONE outlet box AND if they are on adjacent breakers in your breaker box AND if neither of those circuits went anywhere else, then that can be a viable and legal option. The wires would already be there and you could easily change the two individual breakers for one two gang breaker. That would keep you legal. And change the existing outlet(s) for a 230 V one. But that is unlikely unless someone did it deliberately, forseeing this possibility.

                              If even a single one of the conditions above is not true, then it is a bad idea, against the code, and dangerous.



                              Originally posted by no704 View Post
                              Do you have 2 or more separate 110 circuits? Jump them together
                              Paul A.
                              SE Texas

                              Make it fit.
                              You can't win and there IS a penalty for trying!

                              Comment

                              Working...
                              X