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What is the mathematical equation for long time protection curves for protection units on Compact NS /NSX breakers.

The mathematical equation is I²t = constant.
And generally the time tripping is given at 6 Ir.
For example the Micrologic 2 for NSX gives the tripping time 16s at 6Ir.
Then what’s about time tripping at 2Ir?
I²t = I’²t’
t = (2/6)² x 16 = 144 s
This mathematical relationship is available only in long time delay of course when you reach
the Isd (short circuit) threshold it is no longer available.
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