[kennlinie-amz-log-invers-050803, 1, en_US]
Figure 2-94 Trip time characteristics of the inverse time ground fault protection with logarithmic-inverse
time characteristic
Logarithmic inverse
t = 51Ns MAX. TIME DIAL - 51Ns TIME DIAL·ln (Ι/51Ns PICKUP)
Note:
For Ι/51Ns PICKUP > 35 the time applies for Ι/51Ns PICKUP = 35
Logarithmic Inverse Time characteristic with Knee Point (inverse time)
The logarithmic inverse time characteristic with knee point is only used for the standard measurement method
cos φ / sin φ (address 130 S.Gnd.F.Dir.Ch).
The curve (see Figure 2-95) is set by parameters 3119 51Ns PICKUP, 3127 51Ns I T min, 3128 51Ns I
T knee, 3132 51Ns TD, 3140 51Ns T min and 3141 51Ns T max. 51Ns T min and 51Ns T max deter-
mine the range of the tripping time, whereby 51Ns T max of current threshold 51Ns PICKUP and 51Ns T
min of current threshold 51Ns I T min are assigned. In configuration with knee point 51Ns T knee, the
tripping time is determined at transition of the two curve sections with different slopes. The transition point is
defined by current threshold 51Ns T knee. 51Ns PICKUP represents the minimum pickup limit for the
ground fault pickup current of the overcurrent element. As of a maximum secondary current of 1.4 A, the trip-
ping time takes on a constant value. Parameter 51Ns TD serves as a time multiplier for multiplication of the
tripping time.
Functions
2.13 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
214 SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
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