Page 4 of 5 FirstFirst 12345 LastLast
Results 46 to 60 of 69
  1. #46
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    Quote Originally Posted by RustyArc View Post
    Honestly, you'd want to be pretty brave/competent to go scoping the output of a VFD - for starters, the output is probably floating, meaning you really want to differential probe across 2 scope channels (or use a differential probe), and even with 10:1 or 100:1 you really want a decent Cat rating on the probes - having a high divider ratio on a probe does *not* mean it's therefore designed for high voltages.

    I'd expect measuring the voltage with the load attached would go some way towards dealing with the harmonic content. Also I think the DC bus is sometimes readily available for connection to a braking resistor? Again, though, I'd be really careful measuring high DC voltages with a DVM that's not properly designed for high-energy sources.
    The connection for the braking resistor can be used to access the DC bus. But not all VFD's have this connections, it may not be present on economy models. If present, they are usually labelled DC+ and DC-.

    I use a Tektronix THS730A handheld scopemeter, it has two fully insulated input channels. It is an old model (bought in 2001) but works fine for VFD measurements.

  2. #47
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Quote Originally Posted by cba_melbourne View Post
    Drives direct must have had them manufactured on order, as no one else seems to sell them.
    Mine looks nothing like that one, mine is like the ones he is currently selling.
    As I understand it he orders the standard Teco in a box thats big enough to take some sort of mains filter.......without the filter, so there is room for the doubler he adds...... again I have no idea where I got this info as I've never had the cover off mine.

    Quote Originally Posted by cba_melbourne View Post
    Given the steep price of thes Drive Direct units, I wonder if it would not be cheaper to use a normal 400V input VFD and feed it from a 240V/400V step-up transformer up front.
    Given the price of VSD's these days you're like correct. Though you still only end up with a single phase which I have know what DD has done about that. Though you would have a 400V supply for any controls if needed(I think) which could be handy.

    Thanks for the video(omg whats going on with that motor? just some strange mic thing?) and links

    Stuart

  3. #48
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    1,322

    Default

    Quote Originally Posted by Stustoys View Post
    I believe(though cant recall where I got the info from) that my VSD uses a voltage doubler* on the mains side then uses a standard 415V VSD.
    I've always associated "voltage doublers" (a bunch of caps and diodes) with high voltage but very low current circuits, but perhaps a clever engineer has made it work. By default, I'd have assumed there'd be an inductor/transformer based DC-DC converter to boost the DC bus up to a voltage suitable for switching out at 415V levels.

  4. #49
    Join Date
    Nov 2007
    Location
    Near Rockhampton
    Posts
    270

    Default

    Quote Originally Posted by Jayson View Post
    I just borrowed a mates new DSO and went to measure the voltage, turned on the VFD, hooked up the little alligator clip to one of the phases and boom, flash, #$#@....

    Pointing my friend to this thread so he can see it wasn't my fault......

    Lots of information has been given in this thread that could result in the above.

    So, lets just leave it at no VFD will give 380/415 output from 240 in, this seems to be the consensus from those that know.

    Going out to the shed to use my lathe...
    Rather than attempting to measure the voltages with an external meter are these drives capable of displaying the DC bus voltage or the output voltage on the inbuilt display.

  5. #50
    Join Date
    Nov 2007
    Location
    Near Rockhampton
    Posts
    270

    Default

    Quote Originally Posted by RustyArc View Post
    I've always associated "voltage doublers" (a bunch of caps and diodes) with high voltage but very low current circuits, but perhaps a clever engineer has made it work. By default, I'd have assumed there'd be an inductor/transformer based DC-DC converter to boost the DC bus up to a voltage suitable for switching out at 415V levels.
    There is different applications. Voltage multipliers like those used in negative ion generators produce high voltage but very little current.

    Voltage doublers were often used in PC power supplies to allow 120/240 AC input for worldwide use. When used on 240 V systems a conventional rectifier was used. When selected for 120 V operation the input diodes were reconfigured as a voltage doubler.

    These power supplies were rated at hundreds of watts so its easy to imagine the principle could be scaled up for multi horsepower VFD applications.

  6. #51
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    As mentioned earlier, VFD with voltage doubler are mass produced for the North American and Japanese markets. In those cpuntries, most residential houses only have 100 or 110 or 120V power. But their 3 phase motors are 200/400V. So there exists a huge market for 100V in and 200V out VFDs.

    Whereas in 220/240V contries, all newer 3 ph motors are 220/380V, so they can be hooked up directly to a 220V in VFD. There is only a minuscule niche market for customers owning an old motor or machine that only hooks up 380V, and are unwilling to upgrade their old motors. Drives Direct in the UK seem to cater for this very small niche market by adding a voltage doubler to 200V VFDs - at a considerable premium though.

  7. #52
    Join Date
    Dec 2007
    Location
    Melbourne
    Posts
    1,628

    Default

    Quote Originally Posted by cba_melbourne View Post
    As mentioned earlier, VFD with voltage doubler are mass produced for the North American and Japanese markets. In those cpuntries, most residential houses only have 100 or 110 or 120V power. But their 3 phase motors are 200/400V. So there exists a huge market for 100V in and 200V out VFDs.

    Whereas in 220/240V contries, all newer 3 ph motors are 220/380V, so they can be hooked up directly to a 220V in VFD. There is only a minuscule niche market for customers owning an old motor or machine that only hooks up 380V, and are unwilling to upgrade their old motors. Drives Direct in the UK seem to cater for this very small niche market by adding a voltage doubler to 200V VFDs - at a considerable premium though.

    So in summary the poor forgotten OP could have what he was told he has after all?? At a cheaper price from china.

    Thumbsucker have you made any progress?
    …..Live a Quiet Life & Work with your Hands

  8. #53
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    Quote Originally Posted by DSEL74 View Post
    So in summary the poor forgotten OP could have what he was told he has after all?? At a cheaper price from china.
    No, I do not thik so. He has a 3 phase input VFD. I am not aware of anyone making these with voltage doubler input stage (it would triple the number of input doubler capacitors and cost). Only single phase VFDs are offered by drives direct UK.

  9. #54
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Quote Originally Posted by cba_melbourne View Post
    at a considerable premium though.
    I'm not so sure about that. If you are comparing apples with apples. The cost of a new 2.2kW Teco in au would seem to be $1080. So DD isnt to bad compared to that.(anyone know the UK price of one?)

    It will be interesting to find out just what the OP has. If he has to bring out the star point its not the end of the earth. Who knows he maybe happy with half power, my camel back is.

    Stuart

  10. #55
    Join Date
    Aug 2007
    Location
    Melbourne
    Age
    68
    Posts
    1,410

    Default

    Quote Originally Posted by Stustoys View Post
    I'm not so sure about that. If you are comparing apples with apples. The cost of a new 2.2kW Teco in au would seem to be $1080. So DD isnt to bad compared to that.(anyone know the UK price of one?)

    It will be interesting to find out just what the OP has. If he has to bring out the star point its not the end of the earth. Who knows he maybe happy with half power, my camel back is.

    Stuart
    If you want to compare apples with apples, you have to compare the street prices, not the heavily inflated list prices aimed at industrial customers that anyway receive 30%+ trade discounts and do not pay GST.

    Street price for a brand new 2.2kW-3HP sensorless vector TECO is AU$261 plus AU$82 postage:
    http://www.ebay.com.au/itm/3HP-3PH-4...item1c54a30793

    A 3HP VFD from Drives Direct is 475 pounds or 950AU$ plus postage. Not sure if it is an US made TECO though, nor does it anywhere mention it is a modern sensorless vector drive. Direct Drives put their own nameplate and labels over the makers markings. And chances are you could be slugged by our customs for GST if purchase price plus postage exceeds AU$ 1k.:
    http://www.ebay.co.uk/itm/3-HP-DIGITAL-240V-415V-3-PHASE-INVERTER-CONVERTER-BRIDGEPORT-MILL-LATHE-/381284366136?pt=LH_DefaultDomain_3&hash=item58c651b738


  11. #56
    Join Date
    Mar 2006
    Location
    Melbourne
    Posts
    13

    Default

    I have made progress with the VFD and my motor. Thanks allot to NCArcher who helped me via email. The process was relatively simple thanks to plain & simple instruction from NCArcher.

    End the end the motor worked fine without need to make any changes. There was no need to add a 20 amp circuit to the house.

    All I needed to do was purchase some 400 volt rated round lugs and forked lugs and good crimper. It took about 20 minutes and the VFD started up then I simple pressed run and the motor started up. The next step is to program the VFD. Here are some photos.

    IMG_4736.jpgIMG_4737.jpg

  12. #57
    Join Date
    Aug 2011
    Location
    victoria
    Posts
    499

    Default

    Quote Originally Posted by thumbsucker View Post
    I have made progress with the VFD and my motor. Thanks allot to NCArcher who helped me via email. The process was relatively simple thanks to plain & simple instruction from NCArcher.

    End the end the motor worked fine without need to make any changes. There was no need to add a 20 amp circuit to the house.

    All I needed to do was purchase some 400 volt rated round lugs and forked lugs and good crimper. It took about 20 minutes and the VFD started up then I simple pressed run and the motor started up. The next step is to program the VFD. Here are some photos.

    IMG_4736.jpgIMG_4737.jpg

    this is great news . congratulation's.
    so they did what they said then .
    does the motor sound normal and speed up as it should ?
    regards
    Peter

  13. #58
    Join Date
    Mar 2006
    Location
    Melbourne
    Posts
    13

    Default

    The motor hums along nicely with a soft high pitch whizzing sound. It starts slowly revving up over 6 seconds as the hertz increases on the display. The VFD makes more noise in all honesty.

  14. #59
    Join Date
    Jul 2010
    Location
    Melbourne
    Posts
    9,088

    Default

    Hi Ts,
    Good to see you're up and running.

    Quote Originally Posted by thorens View Post
    so they did what they said then
    Well at least in part, it is running on 240V single phase input. But the more interesting part is what the output is, it was always going to run regardless. The question is, does it have 750W or only 300ishW.



    Stuart

  15. #60
    Join Date
    Sep 2008
    Location
    Riddells Creek, Vic.
    Posts
    831

    Default

    Quote Originally Posted by Stustoys View Post
    Hi Ts,
    Good to see you're up and running.


    Well at least in part, it is running on 240V single phase input. But the more interesting part is what the output is, it was always going to run regardless. The question is, does it have 750W or only 300ishW.



    Stuart
    I was also wondering about the power output. This thread has been a little confusing from the start, in my opinion.

Page 4 of 5 FirstFirst 12345 LastLast

Similar Threads

  1. Which way to connect a 3 phase motor?
    By Vernonv in forum METALWORK GENERAL
    Replies: 6
    Last Post: 7th Sep 2014, 07:10 PM
  2. Converting 3 phase star to delta
    By simonl in forum METALWORK GENERAL
    Replies: 36
    Last Post: 24th Oct 2012, 03:32 PM
  3. Star/Delta motor wiring
    By .RC. in forum METALWORK GENERAL
    Replies: 33
    Last Post: 3rd Mar 2012, 11:01 PM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •