lyledunn:
....I also think the tail as are undersized by some margin.
Can't argue with that.
The tripping units should be able to operate at In indefinitely (at least withing reason - a couple of decades non stop might not be good) so I doubt if that is the problem, but it is probably a good move to get confirmation from ABB. You say that the switching device is only rated at 800A which I assume means that while the tripping unit is rated at 1000A, the device it is operating is only rated at 800A (e.g. T6 800). If this is the case then the device itself will be overheating as at 900A it will generate 25% more heat than it can dissipate at its rated temperature (so as a rough guide the temperature rise will increase by 25% which will put extra heat into the undersized tails).
lyledunn:
....I also think the tail as are undersized by some margin.
Can't argue with that.
The tripping units should be able to operate at In indefinitely (at least withing reason - a couple of decades non stop might not be good) so I doubt if that is the problem, but it is probably a good move to get confirmation from ABB. You say that the switching device is only rated at 800A which I assume means that while the tripping unit is rated at 1000A, the device it is operating is only rated at 800A (e.g. T6 800). If this is the case then the device itself will be overheating as at 900A it will generate 25% more heat than it can dissipate at its rated temperature (so as a rough guide the temperature rise will increase by 25% which will put extra heat into the undersized tails).
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