504,214 active members
4,704 visitors online
Register for free
Login
IndustryArena Forum > CNC Electronics > Phase Converters > Phase perfect to 480v transformer help needed .
Page 1 of 2 12
Results 1 to 12 of 17
  1. #1
    Registered
    Join Date
    Oct 2011
    Posts
    19

    Phase perfect to 480v transformer help needed .

    I have a 30hp phase perfect that goes into a sub panel that feeds a haas vf2ssyt at 240v and it also feeds a 240-480v transformer that runs my haas st-10 lathe . when I have power going to the transformer the led lights in my vf2 will flicker a bit . if I turn on the st-10 the light will flicker in there too . not sure what is causing this . I checked the voltage between phases and all is good and I do not see any real fluctuation between phases . everything works fine on the lathe but the flickering light gets a bit annoying . here is a picture of the plate on the transformer .
    Attached Thumbnails Attached Thumbnails s-l1600.jpg  

  2. #2
    Junior Member
    Join Date
    May 2013
    Posts
    471

    Re: Phase perfect to 480v transformer help needed .

    no idea on the flickering lights but how is the 480v secondary grounded?

    it may not pass code but you can use some Y connected capacitors and ground the neutral point. you'll need 3 volt meters connected to an alarm so that when a ground fault occurs you will know it. resistors are also used for this type of situation, common on submarines and other mission critical systems where a single ground fault isn't a high enough priority to justify taking a system offline.

  3. #3
    Registered
    Join Date
    Oct 2011
    Posts
    19

    Re: Phase perfect to 480v transformer help needed .

    I just have it grounded to the transformer case and then back to the panel .

  4. #4
    Junior Member
    Join Date
    May 2013
    Posts
    471

    Re: Phase perfect to 480v transformer help needed .

    not clear to me what you mean. the 480v high voltage side of the transformer is delta connected. its floating relative to the transformer case, its not connected intrinsically to anything at all.


    you can ground one of the phases which will stress the MOV's in your 480v equipment (if it has any) or you can make or buy a zig zag grounding transformer (ideal) or you can use Y connected capacitors (and or resistors) to ground it.


    even just 3, 10uF capacitors should be sufficient, connected from each phase of the 480v delta coil to ground, if each phase to ground voltage is substantially different than 277 volts you have a problem

  5. #5
    Registered
    Join Date
    Oct 2011
    Posts
    19

    Re: Phase perfect to 480v transformer help needed .

    Yes , it is just floating right now .I have the ground from the panel going to the ground lug on the transformer case and then to the ground on the cnc . I have been reading up on corner grounding but it does not sound ideal . do I need any special 10up caps ? do you have to add an extra ground rod to ground it or can I connect it to the ground from the panel ?

  6. #6

    Join Date
    Jan 2005
    Posts
    10137

    Re: Phase perfect to 480v transformer help needed .

    Quote Originally Posted by billwann View Post
    Yes , it is just floating right now .I have the ground from the panel going to the ground lug on the transformer case and then to the ground on the cnc . I have been reading up on corner grounding but it does not sound ideal . do I need any special 10up caps ? do you have to add an extra ground rod to ground it or can I connect it to the ground from the panel ?
    Don't do this, if you are running both at the same time I would say that you have a supply problem, or your PP is right at it's max supply single phase supply

    Does this happen when you only run the VF2 by its self or when both are running VF2 has an amp rating of 70 amps so you are right at the 80 amp rated on your PP for this one machine

    Have you used the right size Ground conductor #7 AWG is the requirment
    Mactec54

  7. #7
    Junior Member
    Join Date
    May 2013
    Posts
    471

    Re: Phase perfect to 480v transformer help needed .

    Quote Originally Posted by billwann View Post
    Yes , it is just floating right now .I have the ground from the panel going to the ground lug on the transformer case and then to the ground on the cnc . I have been reading up on corner grounding but it does not sound ideal . do I need any special 10up caps ? do you have to add an extra ground rod to ground it or can I connect it to the ground from the panel ?
    You would ground the Y connected capacitors to the supply, the main panel, you need 480v rated capacitors.

    There should be no current through the ground wire. But you need at a minimum 3 volt meters and or an amp meter; when a ground fault occurs on the 480v side the voltages will read 0, 480, 480 instead of 277 277 277, and the current through the ground wire from the 10uf capacitors will be on the order of3 amps, instead of zero. you could run that wire through a current transformer and use the output to trigger a disconnect, or you could install a GFCI 3 phase breaker after the 480v transformer.

    the only way to meet the code though, is buy an expensive system to do exactly what i just underlined or find a zig zag grounding transformer, or corner ground.

  8. #8
    Registered
    Join Date
    Mar 2017
    Posts
    284

    Re: Phase perfect to 480v transformer help needed .

    Is the lathe that hard to convert to 220?

  9. #9
    Registered
    Join Date
    Oct 2011
    Posts
    19

    Re: Phase perfect to 480v transformer help needed .

    Quote Originally Posted by mactec54 View Post
    Don't do this, if you are running both at the same time I would say that you have a supply problem, or your PP is right at it's max supply single phase supply

    Does this happen when you only run the VF2 by its self or when both are running VF2 has an amp rating of 70 amps so you are right at the 80 amp rated on your PP for this one machine

    Have you used the right size Ground conductor #7 AWG is the requirment

    the leds in the lathe will flicker with out having the vf2 on at all .I am only measuring 12 amps on each phase going into the lathe so its way below the capacity of the phase perfect . I have 6 awg for a ground wire all the way back to the main panel .

  10. #10

    Join Date
    Jan 2005
    Posts
    10137

    Re: Phase perfect to 480v transformer help needed .

    Quote Originally Posted by billwann View Post
    the leds in the lathe will flicker with out having the vf2 on at all .I am only measuring 12 amps on each phase going into the lathe so its way below the capacity of the phase perfect . I have 6 awg for a ground wire all the way back to the main panel .
    What is your supply this is where the problem is how many amps is the supply for the PP and what size are your cables that feed it
    Mactec54

  11. #11
    Junior Member
    Join Date
    May 2013
    Posts
    471

    Re: Phase perfect to 480v transformer help needed .

    Quote Originally Posted by billwann View Post
    the leds in the lathe will flicker with out having the vf2 on at all .I am only measuring 12 amps on each phase going into the lathe so its way below the capacity of the phase perfect . I have 6 awg for a ground wire all the way back to the main panel .
    what makes you think the power is actually fluctuating? leds are often driven with crappy drivers. some have a hold up time as long as half a second so to actually get them to flicker requires a complete power loss for anything from several cycles to a few dozen, or more cycles.

    the led drivers that have no holdup time at all will flicker with power fluctuations, but its also those same led drivers (with no holdup time, no capacitor to store a charge) that are often crap.

  12. #12
    Registered
    Join Date
    Apr 2015
    Posts
    93

    Re: Phase perfect to 480v transformer help needed .

    I have a 30hp phase perfect that goes into a sub panel that feeds a haas vf2ssyt at 240v and it also feeds a 240-480v transformer that runs my haas st-10 lathe . when I have power going to the transformer the led lights in my vf2 will flicker a bit . if I turn on the st-10 the light will flicker in there too . not sure what is causing this . I checked the voltage between phases and all is good and I do not see any real fluctuation between phases . everything works fine on the lathe but the flickering light gets a bit annoying . here is a picture of the plate on the transformer .
    I'm having the exact same problem on my VF-2SSYT as well and a 355 Perfect phase but on a 240V machine. I thought at first maybe it was the LEDS but I got replacement lights and same problem. Then I plugged them directly to the wall outlet and no flicker at all so I ruled that out. The fact that both of your machines have this flicker is leading me to believe it has to do with the phase converter or wiring of it. My plan was to use a relay to turn the lights on and off and have the LEDs powered by 120v from the wall instead worst case. I would definitely like to know if you were able to sort this out!

Page 1 of 2 12

Similar Threads

  1. Torqcut 30 480v can it be run on 230v? and could it run on single phase?
    By A1CNC in forum Bridgeport / Hardinge Mills
    Replies: 1
    Last Post: 12-17-2016, 08:43 PM
  2. Replies: 8
    Last Post: 07-11-2013, 09:39 PM
  3. Problems with a 480V three phase rotary air compressor
    By Eric MFG in forum Maintenance DIY Discussion
    Replies: 5
    Last Post: 07-10-2012, 02:26 AM
  4. Replies: 3
    Last Post: 09-28-2007, 01:09 PM
  5. 3 phase transformer needed
    By pauluk in forum General CNC Machine Related Electronics
    Replies: 1
    Last Post: 12-26-2005, 10:02 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
  •