Siemens siprotec SJ62 User Manual page 212

50Ns–2 Element
(Definite Time)
50Ns–1 Element
(Definite Time)
Pickup Stabilization
(Definite Time)
51Ns Element (In-
verse Time)
Logarithmic
Inverse
characteristic (In-
verse Time)
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
Similar to the time overcurrent protection function the high set element is named
50Ns-2 PICKUP (address 3113). It is delayed with 50Ns-2 DELAY (address 3114)
and may be set to generate a message or to trip. The latter is only possible if address
3101 Sens. Gnd Fault is set to ON.
The definite tripping characteristic 50Ns-1 is set with addresses 3117 and 3118 (ad-
dress 131 Sens. Gnd Fault = Definite Time).
Pickup of the definite time elements can be stabilized by means of a configurable
dropout time. This dropout time is set in 3121 50Ns T DROP-OUT.
The inverse tripping characteristic 51N-TOC is set with addresses 3119 and 3120
(address 131 Sens. Gnd Fault = User Defined PU).
The logarithmic inverse characteristic (see Figure 2-75) is set in parameters 3119
51Ns PICKUP, 3141 51Ns Tmax, 3140 51Ns Tmin, 3142 51Ns TIME DIAL and
3143 51Ns Startpoint. 51Ns Tmin and 51Ns Tmax define the tripping time
range. The slope of the curve is defined in 3142 51Ns TIME DIAL. 51Ns PICKUP
is the reference value for all current values with 51Ns Startpoint representing the
beginning of the curve, i.e. the lower operating range on the current axis (related to
51Ns PICKUP). This factor is preset to the value 1.1, analogous to the other inverse
time curves. This factor can also be set to 1.0 since in logarithmic inverse curves the
tripping time on a current value, which is identical to the specified pickup threshold,
does not go towards infinity, but has a finite time value.
Figure 2-75 Trip-time characteristics of the inverse-time ground fault protection 51Ns with
logarithmic inverse characteristic
Logarithmic inverse t = 51Ns MAX. TIME DIAL - 51Ns TIME DIAL·ln(I/51Ns PICKUP)
Note: For I/51Ns PICKUP > 35 the time applies for I/51Ns PICKUP = 35
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
210