Siemens SIPROTEC 7SJ62 Manual page 49

Circuit-breaker Maintenance (Breaker)
Parameters 260 to 267 are assigned to CB maintenance. The parameters and the different procedures are
explained in the setting notes of this function (see Section 2.23.2).
Two-phase Time Overcurrent Protection (Protection Operating Quantities)
The two-phase overcurrent protection functionality is used in grounded or compensated systems where inter-
action of three-phase devices with existing two-phase protection equipment is required. Via parameter 250
50/51 2-ph prot the time overcurrent protection can be configured to two or three-phase operation. If the
parameter is set to ON, the value 0 A instead of the measured value for I
comparison so that no pickup is possible in phase B. All other functions, however, operate in three phases.
Ground Fault Protection (Protection Operating Quantities)
Parameter 613 50N/51N/67N w. defines whether ground fault protection, breaker failure protection or Fuse
Failure Monitor is either to operate using measured values (Ignd (measured)) or the quantities calculated
from the three phase currents (3I0 (calcul.)). In the first case, the measured quantity at the fourth current
input is evaluated. In the latter case, the summation current is calculated from the three phase current inputs.
If the device features a sensitive ground current input (measuring range starts at 1 mA), the ground fault pro-
tection always uses the calculated variable 3I0. In this case, parameter 613 50N/51N/67N w. is not available.
Voltage Protection (Protection Operating Quantities)
In a three-phase connection, the fundamental harmonic of the largest of the three phase-to-phase voltages
(Vphph) or phase-to-ground voltages (Vph-n) or the positive sequence voltage (V1) or the negative sequence
voltage (V2) is supplied to the overvoltage protection elements. In three-phase connection, undervoltage pro-
tection relies either on the positive sequence voltage (V1) or the smallest of the phase-to-phase voltages
(Vphph) or the phase-to-ground voltages (Vph-n). This is configured by setting the parameter value in address
614 OP. QUANTITY 59 and 615 OP. QUANTITY 27. With single-phase voltage transformer connection, a
direct comparison of the measured quantities with the threshold values is carried out and the parameterization
of the characteristic quantity switchover is ignored.
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
is used permanently for the threshold
B
Functions
2.1 General
49