Siemens siprotec SJ62 User Manual page 80

User Defined Char-
acteristics (Phases
and ground)
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015
network. For ground and grounded currents with grounded network, you can often set
up a separate grading coordination chart with shorter delay times.
The time multiplier can also be set to ∞. After pickup the element will then not trip.
Pickup, however, will be signaled. If the 51N-TOC element is not required at all,
address 113 Charac. Ground should be set to Definite Time during protective
function configuration (see Section 2.1.1).
Having set address 112 Charac. Phase or 113 = Charac. Ground = User
Defined PU or User def. Reset when configuring the protective functions (Sec-
tion 2.1.1.2), the user specified curves will also be available. A maximum of 20 value
pairs (current and time) may be entered at address 1230 51/51N or 1330 50N/51N
in this case. This option allows point-by-point entry of any desired curve. If during con-
figuration of address 112 was set to User def. Reset or 113 was set to User
def. Reset, additional value pairs (current and reset time) may be entered in
address 1231 MofPU Res T/Tp or 1331 MofPU Res T/TEp to represent the reset
curve.
Since current values are rounded in a specific pattern before they are processed in the
device (see Table 2-3), we recommend to use exactly the same preferred current
values you can find in this table.
The current and time value pairs are entered as multiples of addresses 1207 51
PICKUP and 1208 51 TIME DIAL for the phase currents and 1307 and 1308 for the
ground system. Therefore, it is recommended that these addresses are initially set to
1.00 for simplicity. Once the curve is entered, the settings at addresses 1207 or 1307
and/or 1208 or 1308 may be modified later on if necessary.
The default setting of current values is ∞. They are, therefore, not enabled — and no
pickup or tripping of these protective functions will occur.
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
constant characteristic.
The current values entered should be those from the following table, along with the
matching times. Deviating values MofPU (multiples of PU-values) are rounded.
This, however, will not be indicated.
Current flows less than the smallest current value entered will not lead to an exten-
sion of the tripping time. The pickup curve (see Figure 2-13, right side) is parallel to
the current axis, up to the smallest current value point.
Current flows greater than the highest current value entered will not lead to a reduc-
tion of the tripping time. The pickup characteristic (see Figure 2-13, right side) is
parallel to the current axis, beginning with the greatest curve value point.
2.2 Overcurrent Protection 50, 51, 50N, 51N
78