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  • #16
    UL mandated assumption of current for 1/2 HP at 120V is 9.8A. If the LRA is "only" 5x that, it would be almost 50A. In the case of the OP, the UL (I know, not applicable in Switzerland) assumed current would be 4.9A, and almost 25A draw at 5x for LRA.

    The 5x may be an underestimate, so even of the actual full load current is lower, the LRA may be around the same level.

    The OP could provide a bit more info to assist in finding a solution.
    1601

    Keep eye on ball.
    Hashim Khan

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    • #17
      If this is a universal motor, starting and stall (locked rotor) current can be 4-10 times nominal, and it may be even higher if used on 50 Hz or DC.
      http://pauleschoen.com/pix/PM08_P76_P54.png
      Paul , P S Technology, Inc. and MrTibbs
      USA Maryland 21030

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      • #18
        Originally posted by J Tiers View Post

        Not if it also shuts off other devices like the router and other electronics. The OP has been "very economical" with specifics and information.

        It would help to get a simple, straight answer as to where the RCD is located, and, in fact, what breakers and other overcurrent devices are in-line between the incoming power source and the saw, along with their ratings and the order in which they are put...
        Excellent point.

        I know that due to the wiring in this place I'm in now when I put a sink in the laundry room little did I know that the GFCI outlet I put in to cover the closeness to the sink also covered the outlet on the patio and two outlets in the family room.... It's always a big comfort to know that I'm OK if I come down to the room being flooded and want to watch TV... But yeah, he did mention some other stuff was on the feed through side of the plug didn't he....
        Chilliwack BC, Canada

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        • #19
          o.k., its one of the common 350w asynchronous bandsaws. as mentioned above the gi device is in the main box (i have never seen one in the wall socket).

          so i understand the actual ground has nothing to do with it. its the imbalance between the phase and neutral, right? still curiour as to where this would come from, disregarding the power draw, because that seems not to be the problem. its on a 10 amp breaker, btw.

          Edit: the saw is 15 meters from the main box. no electronics on the saw. i have a 32 amp breaker in the box, so i assume overcurrent is not the problem, although they are slow breakers ("b" from memory). i can weld with 250 amps on a 16 amp breaker.

          Click image for larger version  Name:	0 119.jpg Views:	0 Size:	2.91 MB ID:	1863821
          Last edited by dian; 03-25-2020, 05:33 AM.

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          • #20
            Click image for larger version  Name:	0 120.jpg Views:	0 Size:	2.74 MB ID:	1863829
            Last edited by dian; 03-25-2020, 05:07 AM.

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            • #21
              OK... that's helpful.

              The breaker seems to be a combined type, non-delay (short time delayed type.......No), rated 40A overcurrent or 30 mA imbalance/ground fault, and set up for 3 phase.

              I don't get much from the picture of the breaker box, but a 40A would have a number of smaller breakers (such as your 10A breaker) connected to it for individual circuits, which your statements seems to confirm.

              The 30 mA ground fault rating, which is correct and common for an "upstream" breaker, tend to suggest that there is not a single ground fault with the saw that is causing the problem. It is difficult to see how such a fault could exist only when the saw is stalled, so it is probable that there is no actual ground fault with the saw. Maybe there is so much leakage current due to other electronic devices that just a little extra could trigger the breaker. That's a long shot.

              The alternative is that the saw pulls enough current when stalled that when added to the normal draw of other loads, the total trips the breaker. If the smaller (10A) breaker is a time-delay, and the 40A is not, as implied by the spec of "short time delayed type.......No", then such an action is possible.

              That would mean that the breakers were not properly "co-ordinated" to ensure that the one closest to the "fault" opens first. That is the condition that one normally wants, to avoid the problem that you have, where one circuit fault shuts off a lot of unrelated equipment.

              If a smaller breaker is put with the saw itself, with that breaker being sized to the saw current, then the stalling of the saw should only trip that nearby breaker, and all the others would remain on.

              Data sheet:
              https://translate.google.com/transla...tm&prev=search
              Last edited by J Tiers; 03-25-2020, 11:31 AM.
              1601

              Keep eye on ball.
              Hashim Khan

              Comment


              • #22
                That beaker in particular will not trip on an overload. 40A is the contact carrying capacity. 0.03A on the other end is too sensitive and most input filters will cause it to trip especially VFD and SMPSUs
                Helder Ferreira
                Setubal, Portugal

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                • #23
                  When more than one GF breaker is used in a distribution board you must make sure that you don't mix the neutral wires otherwise you can get it to trip without any apparent reason.
                  Helder Ferreira
                  Setubal, Portugal

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                  • #24
                    Originally posted by Noitoen View Post
                    That beaker in particular will not trip on an overload. 40A is the contact carrying capacity. 0.03A on the other end is too sensitive and most input filters will cause it to trip especially VFD and SMPSUs
                    Larger VFD yes but household switch mode power supplies hardly ever trigger 30mA A-type GFCI.

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                    • #25
                      Originally posted by Noitoen View Post
                      When more than one GF breaker is used in a distribution board you must make sure that you don't mix the neutral wires otherwise you can get it to trip without any apparent reason.
                      Ground and neutral connected somewhere after the circuit panel would also cause GFCI tripping and it would be depend on load current.

                      I'm not sure about Swiss requirements but at least in here it was allowed earlier to do neutral+live wiring to sockets and connect jump wire between neutral and ground in the socket.
                      Causes all kind of funny problems like tripping GFCI's and putting 2A current trough television antenna coax cable.

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                      • #26
                        Originally posted by Noitoen View Post
                        That beaker in particular will not trip on an overload. 40A is the contact carrying capacity. 0.03A on the other end is too sensitive and most input filters will cause it to trip especially VFD and SMPSUs
                        If it is a non-time delay breaker, which the specs on the 40A seem to suggest, and a smaller one following it is a time-delay type, then it CAN open right through the smaller breaker. The time delay on the smaller breaker can allow a larger current for enough time to open even the larger rated one, IF the larger one is not a time delay.

                        If, as seems to be the case, there are other things on the circuits supplied by the 40A combination breaker, then the amount of added current from an overload would not need to be as much. The "base amount" of current for the other devices subtracts from the amount the 40A breaker can carry, so that it is easier to cause it to open on some sort of overload.

                        Per the RCD function.....The 30 mA type is about 10x LESS sensitive as an RCD than the standard "outlet mounted" type in the US, which trips on a mismatch of 0.0035A (3.5 mA). So it should be difficult to cause it to open due to a "leakage" current, or whatever is drawn by one or more input filters, etc. Most normal devices do not cause the US type to open, although they can be a problem if there are a number of computers, etc plugged in. That is one reason why they are used on individual outlets.
                        1601

                        Keep eye on ball.
                        Hashim Khan

                        Comment


                        • #27
                          I had been under the impression that a residential GFCI or RCD outlet would be set to trip at about 30 mA, but that may be the maximum current through the human body that is considered "safe". But the references I found indicate that it is usually 5 mA. Here is a fairly detailed analysis of GFCI design, including a circuit diagram. A few years ago I had a problem with a laundry appliance tripping the GFCI outlet, and IIRC I determined the trip point to be about 20 mA, using a resistor decade box from line to earth ground. I posted a thread here, but I haven't searched for it yet. Another thing to consider is that the differential current transformer is not perfect, and may output a small percentage of the total current due to unequal coupling of the windings to the core, and this may cause an increase of sensor current at higher currents.
                          http://pauleschoen.com/pix/PM08_P76_P54.png
                          Paul , P S Technology, Inc. and MrTibbs
                          USA Maryland 21030

                          Comment


                          • #28
                            Originally posted by J Tiers View Post

                            If it is a non-time delay breaker, which the specs on the 40A seem to suggest, and a smaller one following it is a time-delay type, then it CAN open right through the smaller breaker. The time delay on the smaller breaker can allow a larger current for enough time to open even the larger rated one, IF the larger one is not a time delay.

                            If, as seems to be the case, there are other things on the circuits supplied by the 40A combination breaker, then the amount of added current from an overload would not need to be as much. The "base amount" of current for the other devices subtracts from the amount the 40A breaker can carry, so that it is easier to cause it to open on some sort of overload.

                            .
                            Like Noitoen mentioned this is not a combination breaker, only RCD without overcurrent function. Really common way to install things here in Europe.

                            For example we have
                            powerco-->3x35A ceramic fuses -->30mA RCB(40A)s --> 16/10A branch circuit breakers

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                            • #29
                              Originally posted by MattiJ View Post
                              Like Noitoen mentioned this is not a combination breaker, only RCD without overcurrent function. Really common way to install things here in Europe.

                              For example we have
                              powerco-->3x35A ceramic fuses -->30mA RCB(40A)s --> 16/10A branch circuit breakers
                              OK, I'll believe that as you seem to know it for sure.

                              The specs in translation appeared to show the combo, which we have commonly in US. (the constant 40A over temp can be consistent with that also, most overcurrent breakers have a temperature dependence, although a magnetic type has much less than a thermal type, and tends to be a fast trip unless a delay feature is added. German perfection=magnetic better)

                              That only makes the mystery worse. Now you must explain how it trips with no fault.

                              The only explanations seem to be

                              1) there IS a ground fault

                              2) The breaker is defective

                              3) There IS a (possibly unintended) combi feature through the excess current actually triggering the imbalance function through inherent imperfection in the balance.
                              1601

                              Keep eye on ball.
                              Hashim Khan

                              Comment


                              • #30
                                4. part of the return current on neutral wire goes to somewhere it shouldn't. (some fool connecting ground and neutral)

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