Siemens 7SC80 Manual page 90

Functions
2.2 Overcurrent Protection 50, 51, 50N, 51N
Pickup Stabilization (Definite Time)
The configurable dropout times 1215 50 T DROP-OUT or 1315 50N T DROP-OUT can be set to implement a
uniform dropout behavior when using electromechanical relays. This is necessary for a time grading. The
dropout time of the electromechanical relay must be known to this end. Subtract the dropout time of the
device (see Technical Data) from this value and enter the result in the parameters.
51 Element (Phases) with IEC, ANSI or Recloser Characteristics
Having set address 112 Charac. Phase = TOC IEC or TOC ANSI or Recloser Curves when configuring
the protection functions (Section
will also be available.
If address 112 Charac. Phase was set to TOC IEC, you can select the desired IEC characteristic (Normal
Inverse, Very Inverse, Extremely Inv. or Long Inverse) at address 1211 51 IEC CURVE.
If address 112 Charac. Phase was set to TOC ANSI, you can select the desired ANSI characteristic (Very
Inverse, Inverse, Short Inverse, Long Inverse, Moderately Inv., Extremely Inv. or Defi-
nite Inv.) at address 1212 51 ANSI CURVE.
If address 112 Charac. Phase was set to Recloser Curves, you can select the desired Recloser charac-
teristic (Curve A (101), Curve B (117), Curve C (133), Curve D (116), Curve E (132), Curve
K (162), Curve N (104), Curve R (105), Curve W (138), Curve 2 (135), Curve 3 (140),
Curve 8 (113), Curve 8* (111), Curve 9 (131) or Curve 11 (141))) at address 1226 Recloser
Curves.
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 1210 51
Drop-out, reset will occur in accordance with the reset curve as described before. Recloser curves don't
support disk emulation.
The current value is set in address 1207 51 PICKUP. The setting is mainly determined by the maximum
anticipated operating current. Pickup due to overload should never occur since in this mode, the device oper-
ates as fault protection with correspondingly short tripping times and not as overload protection.
The corresponding time multiplier for an IEC or Recloser characteristic is set at address 1208 51 TIME DIAL
and in address 1209 51 TIME DIAL for an ANSI characteristic. It must be coordinated with the time coordi-
nation chart of the system.
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
If highly sensitive settings close to the load current are required in weak power systems or transformers, the
element can be stabilized via the undervoltage as an additional criterion for the power system fault. The oper-
ating modes can be set in address 1223 VOLT. INFLUENCE. In a voltage-controlled operation, the voltage
threshold is defined via parameter 1224 51V V< below which the current element is released.
51-1, 51-2, 51-3, 51-4 Element (Phases) with All Curves Characteristics
Having set address 112 Charac. Phase = All Curves when configuring the protection functions (Section
2.1.1.2 Setting
curve type IEC, ANSI, or Recloser indivitually. For each element, you select one of tree parameters. The other
two parameters must be set to NO.
For example, for the element 51-1 you can select:
At Address 1236 51-1 IEC Curve the desired IEC–characteristic.
At Address 1277 51-1 ANSI Curve the desired ANSI–characteristic
At Address 1278 51-1 Rec. Curve the desired Recloser–characteristic
The possoble settings for the curves are described in the sections above. If curve type is not selected correctly,
a warning message for this element would be announced.
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 were selected at address 1235
90
2.1.1.2 Setting
Notes), the elements 51-1, 51-2, 51-3, 51-4 are available. For each element, you can select the
Notes), the parameters for the inverse time characteristics
2.1.1.2 Setting
E50417-G1140-C486-A8, Edition 07.2017
Notes).
SIPROTEC Compact, 7SC80, Manual