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  1. #1
    Join Date
    Feb 2013
    N.W Ontario

    Default 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. #2
    Join Date
    Dec 2012
    Sweetwater, TX


    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.

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