OK Andy, is that really what they mean? Please explain.
The vertical bits? - that's how I read them at least - there's a discontinuity between the thermal and magnetic parts - so when the current is right on the boundary between the two (the tiniest fraction below 5x In for a B-type for example) the thing could operate either in thermal mode and take over 10s to open, or it could be in magnetic mode and take (anything up to) 0.1s.
I know some mathematicians who would say that the vertical bit shouldn't really be drawn at all when there's a discontinuity - better to just leave a gap.
Given in BS 7671 land we're not really interested in disconnection times of over 5s, the whole graph is seems of limited use anyway.
OK Andy, is that really what they mean? Please explain.
The vertical bits? - that's how I read them at least - there's a discontinuity between the thermal and magnetic parts - so when the current is right on the boundary between the two (the tiniest fraction below 5x In for a B-type for example) the thing could operate either in thermal mode and take over 10s to open, or it could be in magnetic mode and take (anything up to) 0.1s.
I know some mathematicians who would say that the vertical bit shouldn't really be drawn at all when there's a discontinuity - better to just leave a gap.
Given in BS 7671 land we're not really interested in disconnection times of over 5s, the whole graph is seems of limited use anyway.
