FANOX SIL-A A Series, Руководство пользователя

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4.7 Function 51N. Inverse time calculated neutral overcurrent
This protection function can be set by using the following parameters:
Function Description Minimum Maximum Step Unit Default
51N_1 (*)
51N_2 (*)
Inverse time calculated neutral overcurrent
Function Enable - - No/Alarm/Trip/SHB Trip - No
Curve Type - - (1) -
IEC
Standard
Inverse
Time Dial (TMS) 0.05 25.00 0.01
(2)
1.00
Current Tap 0.050 20.000 0.001 xIn 5.000
Time Delay 0.000 300.000 0.001 s 0.200
(*) Optional depending on model
(1)
Definite time and 8 curves are included to be selected by the user:
TYPE NAME
DT Definite Time
IEC Standard Inverse
Very Inverse
Extremely Inverse
Long Time Inverse
Short time Inverse
IEEE Moderately Inverse
Very Inverse
Extremely Inverse
(2) The range of the time Multiplier setting will depend on the curve. The range of this setting for each
curve family is as follows:
TIME DIAL (TMS)
Description Minimum Maximum Step Unit Default
IEC Time Multiplier 0.05 1.00 0.01 - 1.00
IEEE Time Multiplier 0.10 25.00 0.01 - 1.00
If the option ‘Defined time ’ is selected for the curve setting, the unit behaves like an instantaneous
directional overcurrent unit. In this case, the unit time delay is adjusted by using the parameter ‘Time
delay’ . If a curve is selected for the curve setting, the time delay depends on the curve, dial (TMS) and
tap settings.
If the unit operates as 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.
If the unit operates as defined time, the accuracy of the Time Delay is equal to the set time delay ±35ms
or ±0.5% (whichever is greater).If a curve is selected for the curve setting, the accuracy of the time delay
is equal to the theoretical time ±30ms or ±5% (whichever is greater).
The curves used are IEC 60255-151 and IEEE, which are described in the corresponding section.