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If the option "Defined time" is selected for the curve setting, the unit behaves like an instantaneous
overcurrent unit. In this case, the unit operating time is set by the parameter "Operating time".
If a curve is selected for the curve setting, the operating time depends on the curve, dial and tap
settings.
If the unit operates with defined time, the function is activated at 100% of the set tap value, and it
deactivates at 95%.
If the unit operates with a curve, the function is activated at 110% of the set tap value, and it
deactivates at 100%.
The reset is instantaneous in both cases.
The activation time is accurate to ±5% or ±30ms, whichever is greater, of the theoretical activation
time.
The curves used are IEC 60255-151 or IEEE, which are described in the "Curves" section.
4.3. 50N/G Function. Neutral instantaneous overcurrent
This protection function can be set by using three parameters:
Function Description Minimum Maximum Step Unit Default
50N/G Neutral instantaneous overcurrent
Permission - - Yes/No - No
Tap 0,10 30,00 0,01 I nominal 1,00
Operating time 0,02 300,00 0,01 s 0,2
The operating time is completely independent from the operating current that flows through the device,
so if the neutral current exceeds its predetermined value for an equal or greater amount of time than
this pre-set value, the protection function activates (trips) and does not reset itself until the value of the
phase drops below the point of current pick-up.
The function activates at 100% of the pre-set input and deactivates at 95%. The reset is
instantaneous.
The accuracy of the operation time is equal to the pre-set time ±30ms or ±0.5% (whichever is greater).