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  1. #21
    Quote Originally Posted by Dwayne Dibbley View Post
    Thanks, I think i over think things to much, just one query what advantage is the latching relay over just running the 24v circuit through the contactor dc coil?
    Well think about just what would happen if you just wired 24V direct thru the E-stop to contactor with nothing else between.!! . . . . . Yes machine would stop when pressed but what would happen when E-stop released and contactor turns back on.?? . . . . . . . . . . . . . . . . Argh crash bang whollop when machine instantly takes off again with no idea where it is or where it's going.!

    Yep the drives would turn on and motors would setoff again and because you didn't inform control software E-stop happened then instantly machine would carry on but now with no idea where it is.!!

    The whole point of the Latching safety system is to allow a controlled Stop and Safe Re-start.
    Last edited by JAZZCNC; 12-04-2015 at 03:53 PM.

  2. #22
    OK, now that makes sense. So as you suggested run the software Estop loop through the 3rd loop on the contactor, then when the latch is released the contactor cuts power and triggers the software e-stop, and build it as per the first schematic i posted ( less the extra stop button ).

    second point, are the MCB's i selected of the correct rating for the intended use?

    6A C Type for the 24V/6.5A stepper driver PSU (meanwell spec states 2A/230VAC so should the breaker cover the input Amps or the 24v 6.5A? )
    16A C type for 1.5KW VFD ( 1500W @ 240V reads more to 8 AMP? )
    2A B Type for the Saftey Circuit 24V/2.5A PSU ( again link the stepper PSU should this be sized for the input A and not the output ?)

    Thanks again for your help.

  3. #23
    I Have done some digging and have come up with these as the min MCB's required based on 230V calculations:

    24V DC PSU ( Latch relay ) - 3A MCB B type- (345W 230v 1.5A)
    24V DC PSU ( Steppers ) - 3A MCB B Type - (460W 230v 2A)
    VFD - 10A MCP C type - (1500W 230v 6.5A?)

    does that sound possible or would it be more of trial and error ie buy a couple of different sizes and try the smallest that does not trip on power up?


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