•
Measurement with instantaneous values
This procedure compares the instantaneous values to the set threshold. The element picks up at 2 · 2 ·
setting value (rms). It does not perform a mean-value calculation and is thus sensitive with regard to
disturbances. This measurement method should only be selected if an especially short pickup time of the
element is required. In this measurement procedure, the operating time of the element is reduced
compared to the measurement of effective values or fundamental harmonics (see “Technical Data”).
The type of the comparison values can be set under the following addresses:
50-3 element Address 1219 50-3 measurem.
50-2 element Address 1220 50-2 measurem.
50-1 element Address 1221 50-1 measurem.
51 element Address 1222 51 measurem.
51-1 element Address 1232 51-1 measurem.
51-2 element Address 1244 51-2 measurem.
51-3 element Address 1258 51-3 measurem.
51-4 element Address 1266 51-4 measurem.
50N-3 element Address 1319 50N-3 measurem.
50N-2 element Address 1320 50N-2 measurem.
50N-1 element Address 1321 50N-1 measurem.
51N element Address 1322 51N measurem.
51N-1 element Address 1332 51N-1 measure.
51N-2 element Address 1338 51N-2 measure.
51N-3 element Address 1344 51N-3 measure.
51N-4 element Address 1350 51N-4 measure.
High-Set Current Elements 50-2, 50-3 (Phases)
The pickup currents of the high-current elements 50-2 PICKUP or 50-3 PICKUP are set at address 1202
and 1217. The corresponding time delay 50-2 DELAY or 50-3 DELAY can be configured at address 1203 or
1218. It is usually used for current grading for large impedances as occur in transformers. The time delay is set
to pick up on short circuits up to this impedance.
Example of the high-set current element 50-2 PICKUP: Transformer used for busbar supply with the
following data:
Rated apparent power
S
NomT
= 16 MVA
Transformer impedance ZT = 10 %
Primary nominal voltage V
Nom1
= 110 kV
Secondary nominal voltage V
Nom2
= 20 kV
Vector groups Dy 5
Neutral point Grounded
Fault power on 110 kV-side 1 GVA
Based on the data above, the following fault currents are calculated:
Three-Phase High Voltage Side Fault Current
at 110 kV = 5250 A
Three-Phase Low Voltage Side Fault Current at 20 kV = 3928 A
On the High Voltage Side Flowing at 110 kV = 714 A
The nominal current of the transformer is:
Ι
NomT, 110
= 84 A (High Voltage Side)
Ι
NomT, 20
= 462 A (Low Voltage
Side)
Current Transformer (High Voltage Side) 100 A/1 A
Current Transformer (Low Voltage Side) 500 A/1 A
Functions
2.2 Overcurrent Protection 50, 51, 50N, 51N
88 SIPROTEC Compact, 7SC80, Manual
E50417-G1140-C486-A8, Edition 07.2017
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