BS 1362 fuse standard

[Andrew Gabriel]

I was trying to work out the time/current factor for BS 1362 plug top fuses for a fault current. Figure 2 is the logarithmic graph. They've managed to plot the curves on log base 11 axes (labeled in base 10)!

It makes a difference of 100A in the answer, depending how you read the broken graphs!

[Robin]

I'll risk ridicule: is it just that they have used minor grid lines at

1.5, 15 etc? I suggest that becauSe of the way the 2nd interval in each major grid is smaller than both the 1st and 3rd intervals. And because if I draw a log-log graph in Excel using base 10 it looks like figure 2 but for the fact it don't have the (spurious? misleading?) minor grid line.

I'll go to the stocks ready to receive punsihment ;(

[Andrew Gabriel]

I think you might be right - the extra line could be 1.5

Every alternate line is labeled, and the labels run:

10^n 2 4 6 8 10^(n+1)

So the line between 10^n and 2 could be 1.5. It sure can't be 1!

If so, the axis lines are:

10^n 1.5 2 3 4 5 6 7 8 9 10^(n+1)

Thanks - I can now read the value off the graph.

[John Rumm]

You mean this one:

I think they have just added extra "half" lines on the first two divisions since they are quite large in comparison to the rest in each decade.