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  1. #1
    I live in an remote country area where we often get 'micro blips' in the power supply.

    For my office computers I use a UPS which smooths these out and can sustain the computers for around 15 minutes, long enough to enable a proper shut-down if it is a full power cut.

    It occured to me that the CNC router I am just on the point of installing could be adversely affected by these blips, obviously a full power cut is a different thing altogether.

    Can anyone offer any advice on this issue please? What would be the likely effects on the machine and controller if a bilp or series of blips occurred mid cut?

    Any ideas how I could, cost effectively, protect my machine and any work in progress??

    As a supplementary question, what is the effect of a work piece if there is a total power cut? does it just run down nicely, or start snapping tools etc?

    All advice most welcome.

  2. #2
    Any cut in power to the PC or Controller is disaster while cutting a job due to lost signals causing positional error. Even tiny drop outs will have an effect.

    The affect of full power cut will depend on several variables and how the Control system is designed. The type of power supply for the drives, spindle type and settings, feedrate, tool size, material type, depth of cut, Axis/gantry weight etc will all play there part so not something that be predicted accurately.

    For instance toroidal PSU stores energy in it's capacitors so drives and motors will remain under power until drained so machine will run on slightly after power drops.
    Spindles will run on for so long depending on type, power rating, tooling size etc. For instance VFD's often used for spindles have capacitors which will allow spindle to run on if not commanded to stop.

    My advise would be to use UPS that can keep the PC/controller and VFD powered and allow for a Safe E-Stop in the event of power cut. This will mean the Control system will have to be designed in such away that it can detect power loss and shut down important areas quickly and safely.

  3. #3
    I live in Spain in a similar area. I still remember the first laptop i bought here, died after 10 min. From that moment on, all my computers and stuff is connected through UPS. I have a couple of them, most are 1500W. And if not through UPS, then through surge protector.

    The CNC has connected the PC and the machine to the UPS. Only the VFD goes through spike protection only. But i have a wire from the VFD to the BOB /the reset button line/ that tells the BOB if the VFD is online, when not, it resets and all stops.

    The VFD i have /Mitsubishi/ is actually protected against spikes and quite some voltage drops or rises, according to the manual.

    Its useful cause not only the spikes. Sometimes they decide to repair the electricity of a neighbor or on the street while the machine is running.

    Its possible also to connect instead to the reset line, for example to play like "pause" button on whatever input, so you can later resume, but the lag till mach3 stops the machine is so big, that i would NOT do that.
    project 1 , 2, ...

  4. #4
    OK thanks for the feedback, but as a Newcomer, what is VFD and BOB?

    Any recommendations of UPS etc.?

  5. #5
    Quote Originally Posted by racerbear02 View Post
    OK thanks for the feedback, but as a Newcomer, what is VFD and BOB?

    Any recommendations of UPS etc.?
    VFD- Variable frequency drive , the thing that controls the spindle motor
    BOB- Breakout board, the mother board of your machine

    I got my 2 x 1500W UPS from bootsale for 15euro each. New are 500euro each

    From any PC store chain 1000W should be say 50-100euro each. You will need one only. Use the single outlet/no ups but only protector/ for the VFD
    project 1 , 2, ...

  6. #6
    Thanks for that

  7. #7
    All VFD have screw terminals where they have relay contactor that switches on or off when the spindle motor is powered or not. Read the manual.

    From there you take 2 wires and wire them splitting the line of the big red button saying Estop. Read the BOB manual and be careful not to split 220VAC, cause some Estop buttons have double chain, one for the small voltage signals/5-24VDC depending on the BOB/ and one for directly cutting the 220VDC power/mine for example is made like that/
    project 1 , 2, ...

  8. #8
    Thank you yet again, I will study the manual etc when I get it

  9. #9
    OK, I now have the machine and as the spindle is 2.2 kw and it and all the electronics are wired in together and fed by one power supply, what sort of power UPS should I be looking at?? 3kw?? or is there any other solution? as a UPS of that power will cost a fortune.

    As always, thanks in advance.

  10. #10
    no need for UPS for the VFD. It will be extremely expensive
    project 1 , 2, ...

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