Miller Electric

Welding Discussion Forums

Home » Resources » Communities » Welding Discussion Forums

  • If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.


Announcement Module
No announcement yet.

New Synchro 250dx....Old question

Page Title Module
Move Remove Collapse
Conversation Detail Module
  • Filter
  • Time
  • Show
Clear All
new posts

  • New Synchro 250dx....Old question

    I ordered a new 250dx and need to know about breaker size.About the highest I will run the machine is 250amps@68En.I figure the draw will be about the same as 270 balanced or so. If I run a 100amp breaker will the machine kick off first?Or will the breaker trip in panel box.I obviously want machine to trip first,leaving fan on.My present wire is #6 TEC armoured cable which I feel will run the 100amp Ok,but if I need a 125amp breaker I will run a bigger cable.Anyone have any experience on this?


  • #2
    Don't know if you have the manual yet.

    Page 30 shows the electrical service recommendations.
    125A is the Max recommended circuit breaker for 220V input without PFC.
    Minimum input conductor is 6 AWG wire

    With PFC the breaker is smaller, 90A for 220V input and 80A for 230V input voltage.
    Minimum input conductor is 8 AWG wire

    Page 13 shows the input current for single-phase 60Hz.
    It makes a pretty good difference if your model has Power Factor Correction (PFC) built in or not.

    At 250Amps AC balanced- 40% duty cycle at 230V input the Current input is as follows:
    No PFC - 96A - (2.8A while idling)
    With PFC - 71A - (49.5A while idling)

    Hope that helps.
    Last edited by clint738; 02-15-2013, 03:25 PM.


    Special Offers: See the latest Miller deals and promotions.