FANOX SIL B, User Manual, Page: 32 / 311

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4.3. Functions 50N/G_1 and 50N/G_2. Instantaneous neutral overcurrent
This protection function can be set by using three parameters:
Function Description Minimum Maximum Step Unit Default
50N/G_1
50N/G_2
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 0.02
The operating time is completely independent from the operating current that flows through the
equipment, so if the neutral current exceeds its predetermined value for an equal or greater amount of
time than this preset value, the protection function activates (trips) and does not reset itself until the
average value of the phase drops below the point of current tap.
The function activates at 100% of the preset input, and deactivates at 95%. The reset is instantaneous.
The accuracy of the operation time is equal to the preset time plus a maximum of 30 ms.
4.4. Function 67N1 & 67N2. Inverse-time neutral directional overcurrent
Two neutral directional units are available: 67N1 y 67N2.
This function uses the residual voltage as a polarization magnitude and the residual current as an
operating magnitude. The intervention sector is defined in the following way: the operating angle is
rotated anticlockwise from the residual voltage, which gives us the maximum torque direction. A cone is
drawn, with the half-cone angle adjusted, over this maximum torque direction.
If the directionality option is not activated, the 67N function behaves like a 50/51N/G function.
The actuation time starts when the following conditions are met simultaneously:
•
Residual voltage higher than adjusted
•
Residual current higher than adjusted
•
The phase shift of residual current and residual voltage is such that the residual current is
inside the intervention sector.