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Thread: Whatsa Sixis?

  1. #21
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    Quote Originally Posted by Peter from Holland View Post
    And if the OP has 120volts only.
    In the US the standard feed is two-phase 120/240V at 60Hz. So almost certainly the OP has 220-240VAC available.

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    Uhhh, Ballen, I think you mean American standard is single phase 120/240v 60Hz...

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    Quote Originally Posted by lucky7 View Post
    Uhhh, Ballen, I think you mean American standard is single phase 120/240v 60Hz...
    Believe Bruce is correct here. 120 is single phase, but most (all?) US households supplied with ~220-240 two phase-- there are two hot legs.

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    Quote Originally Posted by sneebot View Post
    , but most (all?) US households supplied with ~220-240 two phase-- there are two hot legs.
    its not two phase. 220 or 240 into a house is single phase, i.e there is only one sine wave on the scope

    Nice looking mill. They are very similar to an Aciera F1 and i believe a lot of the parts are interchangeable. I've been told it has a better spindle design

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    Mcgyver is correct. The two hot legs are in phase. One sine wave per cycle.

    L7

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    Quote Originally Posted by lucky7 View Post
    Mcgyver is correct. The two hot legs are in phase. One sine wave per cycle.

    L7
    They're in anti-phase. If they were in phase, their difference would be zero.

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    I suspect Sigurasg means the same thing as me, single phase, not double. In phase, from my very rusty college physics too many years ago, means same direction from zero thru the whole sine wave. The amplitude is double in this case because you have two hots, each 115v in the same phase. Hope that makes sense?

    Still, single phase is norm in North America for homes, unlike much of Europe. IMHO, Europe’s choice is better.

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    I was thinking about putting the mill in a workshop that's in my house where I don't have 3 phase available now. I have a rotary phase converter in the garage that will let me use the mill in the near term.

    The smaller motor is for the x axis feed.
    00o0o_7g357ryvlux_1200x900.jpg
    There is a bit of the plumbing there for coolant but it has no reservoir or pump now.

    I think the Aciera F1 is a neat little mill but I can't think of anything that I need to make that I would use it for. This mill is probably closest to the Aciera F2. The X, Y, Z travels are 320, 120, 370 mm vs 225, 125, 225 mm for the Aciera F2. They have similar weight (250 Kg) and power (500 vs 600W). The quill and power feed aren't there on the F2 though.

    The terminology in our power system is confusing. In the US we have a split phase system, single phase that is split with a center tap transformer into two legs that are 180 degrees out of phase. By definition this is not a two phase system as there is no "rotation" between the phases.
    "Since the two phasors do not define a unique direction of rotation for a revolving magnetic field, a split single-phase is not a two-phase system." Split-phase electric power - Wikipedia
    So even though there are two legs that are 180 degrees out of phase it's not considered a 2 phase system. Historically there was a 2 phase power distribution system with the legs being 90 degrees out of phase.

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    I’m not sure if I can do any better, but this is what I understand- please correct me if wrong...


    L1——->>>——-N——->>>——-L2

    Equals single phase center tap supply. (crude diagram!)

    L1 to N is 115v. N to L2 at exactly the same time is 115v zero degrees on the sine wave related to L1 to N (ie single phase). Being AC current this reverses 60 times per second in N America. N is supposed to be neutral (ideally zero potential) with the degree of rotation/sine wave of the current flow at any one instant L1 to N and L2 to N cancelling each other out. They are 180 degrees to each other. I think this is what sigurasg is saying? I found the term anti phase to be confusing.

    Does this make sense?

    L7

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    Lucky 7: I think you've got the idea. When running a single 240V appliance the neutral isn't connected so no current flows. When L1 is at its maximum voltage, L2 is at it's minimum. So peak voltage in L1 in a 120V system will be 170V when L2 is -170V. Voltage is a relative measurement. The voltage of L1 relative to L2 will be 340V. The voltage waveforms will be mirror images relative to N.
    When an electrician wires a panel with a bunch of 120V circuits they try to put equal loads on L1 and L2. It usually wouldn't be perfectly equal so some current would flow in the Neutral lead back to the power companies transformer.
    That being said my experience is almost entirely with analog signal level electronics and digital circuits so I'm no expert in power systems. I have bad habits after working for years around low voltages and I'm a hazard around these voltage levels.

    I wired up another socket on my rotary phase converter and plugged in the Sixis. When I turned it on there was a low level hum that lasted a second or two and stopped. Then nothing. I thought oh shit. The buttons then did nothing. I checked the socket on the phase converter and the voltages looked OK. So I opened up the electrical box on the Sixis and found 3 loose wires on one of the electrical objects that I didn't recognize. So I connected them again and it worked. Most of the wiring in the box looked very professional, but these wires didn't. There were on the underside of the unknown electrical object so I don't think that whoever worked on it got on their back to look at the wires when they connected them.
    Last edited by Nice Guy; 09-17-2020 at 11:13 AM.

  11. #31
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    Thanks for the discussion.

    From the logical point of view:

    single phase: ground plus one live "phase" line
    two phase: ground plus two live "phase" lines, which differ from each other
    three phase: ground plus three live "phase" lines, which differ from each other
    four phase: ground plus four live "phase" lines, which differ from each other
    ...
    and so on.

    Traditionally, US "two phase" systems had the two live lines 90-degrees apart, not 180. So the case where the two live lines are 180 degrees apart is called "split phase" rather than two phase.

    Bottom line: use a 220-240V single phase in, three phase out VFD, and feed the input from your household split phase 240V.

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    I watched this video a while ago, I thought it explained the US system well

    The US electrical system is not 120V - YouTube

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