Siemens SIPROTEC 4 7SJ61 Manual page 63

The time multiplier can also be set to ∞. In this case, the element will not trip after pickup. However, pickup
will be signaled. If the 51 element is not required at all, address 112 Charac. Phase should be set to Defi-
nite Time during protection function configuration (see Section
51N Element (ground) with IEC or ANSI Characteristics
Having set address 113 Charac. Ground = TOC IEC when configuring the protection functions (Section
2.1.1 Functional
address 113 Charac. Ground = TOC IEC the desired IEC characteristic (Normal Inverse, Very
Inverse, Extremely Inv. or Long Inverse). If address 113 Charac. Ground = TOC ANSI, you can
select the desired ANSI characteristic (Very Inverse, Inverse, Short Inverse, Long Inverse,
Moderately Inv., Extremely Inv. or Definite Inv.) in address 1312 51N ANSI CURVE.
If the inverse time trip characteristic is selected, it must be noted that a safety factor of about 1.1 has already
been included between the pickup value and the setting value. This means that a pickup will only occur if a
current of about 1.1 times the setting value is present. If Disk Emulation was selected at address 1310 51
Drop-out, reset will occur in accordance with the reset curve as described before.
The current value is set in address 1307 51N PICKUP. The setting is mainly determined by the minimum
anticipated ground fault current.
The corresponding time multiplier for an IEC characteristic is set at address 1308 51N TIME DIAL and at
address 1309 51N TIME DIAL for an ANSI characteristic. This has to be coordinated with the grading coordi-
nation chart of the network. For ground 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 ∞. In this case, the element will not trip after pickup. However, pickup
will be signaled. If the 51N-TOC elementt is not required at all, address 113 Charac. Ground should be set
to Definite Time during configuration of the protection functions (see Section
User-defined Characteristics (phases and ground)
Having set address 112 Charac. Phase or 113 = Charac. Ground = User Defined PU or User def.
Reset when configuring the protection functions (Section
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. When setting address
112 = User def. Reset or 113 = User def. Reset, additional value pairs (current and reset time) may
be entered in address 1231 MofPU Res T/Tp or1331 MofPU Res T/TEp to represent the dropout curve.
Since current values are rounded in a specific pattern before they are processed in the device (see
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 values at addresses 1207
or 1307 or/and 1208 or 1308 can be modified later to allow moving the curve in a different direction.
The default setting of current values is ∞. They are, therefore, disabled and no pickup or tripping of these
protection functions will occur.
The following must be observed:
•
The value pairs should be entered in increasing sequence. If desired, fewer than 20 pairs can be entered.
In most cases, about 10 pairs is sufficient to define the characteristic accurately. A value pair which is not
used has to be made invalid by entering "∞" for the threshold! The user must ensure that 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.
Currents smaller than the current value of the smallest curve point will not lead to an extension of the
tripping time. The pickup curve (see
smallest current value point.
Currents larger than the largest current value entered will not lead to a reduction of the tripping time.
The pickup curve (see
greatest current value point.
SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016
Scope), the parameters for the inverse time characteristics will also be available. Specify in
Figure
Figure 2-15, right side) runs parallel to the current axis, beginning with the
2.2 Overcurrent Protection 50, 51, 50N, 51N
2.1.1.2 Setting
2.1.1.2 Setting Notes), user-defined curves will
2-15, right side) runs parallel to the current axis, up to the
Functions
Notes).
2.1.1 Functional Scope).
Table 2-3),
63