Electrical Protection for Machine shop in the woods
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  1. #1
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    Default Electrical Protection for Machine shop in the woods

    This is a question for myself and a buddy in a similar situation. I searched the forums but did not come up with much.

    What should be in place regarding protection to the machines from power flickers and brown outs? I live pretty far out and it can get rather windy in the winter months. Surge protection seems like a given, but is it necessary to have some form of brownout protection?

    Machines in question are modern CNC mills and Lathes. (brother speedio, nakamura lathe)

    Thank you.

  2. #2
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    My phase perfect will shut down if voltage gets too high OR too low.

  3. #3
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    First I would ask brother, they seem like the kind of company that would know things

    Second, CNC's are meant for harsh environments with other giant machines running nearby, voltage spikes, power droops etc

    While a power outage always freaks me out [my machines!!!!] it has thusfar[knock wood] never damaged a machine

  4. #4
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    Years ago I worked in a facility that had very sensitive equipment that was driven by motor generators, amplidynes, and tube based amplifiers. The system was remarkably resilient to power fluctuations due to the energy stored rotating mass of the motor generators, and the carry-on capability of a tube amplifier. We could carry through the loss of up to 70 cycles.

    When we upgraded to solid state controls, the system became extremely sensitive to power fluctuations since very little energy was actually stored in the drive system. We'd lose the entire process after 2-3 cycles.

    To overcome this problem, we installed rotary UPS equipment on the critical systems. They're basically a big flywheel that stores the energy, and electronics that use this energy to provide brief support of the incoming power. They were extremely reliable, took little maintenance, and performed flawlessly. (I won't bore you with the issues of the battery systems on other devices).

    While probably too expensive new, they do show up on the used marked occasionally. It wasn't an issue for us (we had our own power plant), but I wonder if they could be driven by single phase and run continuously outputting 3 phase....

  5. #5
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    The drive electronics and drive motors tend to be pretty robust.
    Because they must routinely absorb huge inrush currents and dumped-back emf power, and mostly the peaks are many times the rated power.

    So the whole system is built robust.

    A 2.5 kW lathe can dump 8-16 kW in an estop, or more.
    Sure, some dump some power to resistors and some to the grid, but still.
    And a 25 kW or 40 Hp continuous duty spindle motor is an excellent sink and stabiliser for maybe 5x or 120 kW for sub-second loads.

    But remote brownouts may last seconds, vs some fractions of a second in an estop.
    Depends on where you are and how much the voltage drops, I think.

    A rotary 3-phase converter 1:1 is the only cheap thing I can think of to stabilise industrial power for 2 machines.

    Surplus center, nos, dirt cheap big motors abound and can store a lot of energy for very little cost, and you dont need to run them 24x7 if you don´t want to.

    Electronics, batteries, etc will be extremely expensive for such power levels.
    You could get a tesla powerpack, 100 kW, that is the cheapest, but you wont like the price.


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