Siemens siprotec SJ62 User Manual page 214

Determination of
Ground-Faulted
Phase
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
The following must be observed:
• The value pairs should be entered in increasing sequence. Fewer than 20 pairs is
also sufficient. In most cases, about 10 pairs is sufficient to define the characteristic
accurately. A value pair which will not be used has to be made invalid by entering
"∞" for the threshold! The user must ensure the value pairs produce a clear and con-
stant characteristic.
The current values entered should be those from Table 2-3, along with the matching
times. Deviating values MofPU (multiples of PU-values) are rounded. This, howev-
er, will not be indicated.
Currents less than the smallest current value entered will not lead to an extension
of the tripping time. The pickup curve (see Figure 2-77) continues, from the smallest
current point parallel to the current axis.
Currents greater than the highest current value entered will not lead to a reduction
of the tripping time. The pickup curve (see Figure 2-77) continues, from the largest
current point parallel to the current axis.
Table 2-12 Preferential values of standardized currents for user-defined tripping curves
MofPU = 1 to 1.94
1.00 1.50 2.00
1.06 1.56 2.25
1.13 1.63 2.50
1.19 1.69 2.75
1.25 1.75 3.00
1.31 1.81 3.25
1.38 1.88
1.44 1.94
Figure 2-77 Use of a user-defined characteristic
The ground-faulted phase may be identified in an ungrounded or resonant-grounded
system, if the device is supplied by three voltage transformers connected in a ground-
ed-wye configuration. The phase in which the voltage lies below setting VPH MIN at
address 3106 is identified as the faulty phase as long as the other two phase voltages
simultaneously exceed the setting VPH MAX at address 3107. The setting VPH MIN
must be set less than the minimum expected operational phase-to-ground voltage. A
typical setting for this address would be 40 V. Setting VPH MAX must be greater than
2.12 Ground Fault Protection 64, 67N(s), 50N(s), 51N(s)
MofPU = 2 to 4.75 MofPU = 5 to 7.75
3.50 5.00
3.75 5.25
4.00 5.50
4.25 5.75
4.50 6.00
4.75 6.25
MofPU = 8 to 20
6.50 8.00 15.00
6.75 9.00 16.00
7.00 10.00 17.00
7.25 11.00 18.00
7.50 12.00 19.00
7.75 13.00 20.00
14.00
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