The vertical part is a mathematical error Andy, it should certainly not be there, see the spur thread. It certainly does not mean a range of values, and essentially should not be drawn like that. You are correct in that the graph is discontinuous and the mathematical reasons are as follows:
The two axes on a graph are related to one another by an equation, which may be very curious and complex. However, there is a proviso that the slope may never be infinite, which means that the relation between the axes is no longer present. There is no equation available that gives a "range of values" as the answer, it is not possible without cheating. The error is that the magnetic part is completely separate from the thermal part and they may never join. True there is a point where one takes the place of the other, but this point is not really defined. I also do not see why the vertical lines stop at 0.1 seconds, this is completely arbitrary and does not reflect the real operation. The rest of the curve over 5 seconds is very useful, it shows (as do the fuse graphs) what happens when the fuse is operated at less than the disconnection time (which is normal operation). You depend on this in your house DNO supply every day, and probably the cutout fuse too, it is "normal" not during fault operation.
The vertical part is a mathematical error Andy, it should certainly not be there, see the spur thread. It certainly does not mean a range of values, and essentially should not be drawn like that. You are correct in that the graph is discontinuous and the mathematical reasons are as follows:
The two axes on a graph are related to one another by an equation, which may be very curious and complex. However, there is a proviso that the slope may never be infinite, which means that the relation between the axes is no longer present. There is no equation available that gives a "range of values" as the answer, it is not possible without cheating. The error is that the magnetic part is completely separate from the thermal part and they may never join. True there is a point where one takes the place of the other, but this point is not really defined. I also do not see why the vertical lines stop at 0.1 seconds, this is completely arbitrary and does not reflect the real operation. The rest of the curve over 5 seconds is very useful, it shows (as do the fuse graphs) what happens when the fuse is operated at less than the disconnection time (which is normal operation). You depend on this in your house DNO supply every day, and probably the cutout fuse too, it is "normal" not during fault operation.
