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4.5
Ground Fault Differential Protection in Resonant-grounded /
Isolated Systems
Pickup Values
Differential current;
87N L: IN(s)>
Operating Times
The operating times depend on the communication speed. The following data require a transmission rate of 512 kbit/s.
Pickup/trip times of the 87N L: IN(s)> element at
50 Hz or 60 Hz approx.
Dropout times of the 87N L: I-DIFF> element
approx.
Minimum current for direction determination
Delay of the 87N L: I-DIFF> element approx.
Frequency range
Time Delays
Tripping delay
Expiry tolerances
The set times are pure time delays.
Frequency Operating Range
Operating Range
SIPROTEC 4, 7SD80, Manual
E50417-G1100-C474-A2, Edition 02.2018
4.5 Ground Fault Differential Protection in Resonant-grounded / Isolated Systems
= 1 A
0.003 A to 1.000 A
Ι
Nom
minimum
minimum
0.00 s to 320 s
87N L:Trip-
Delay
1 % of setting value or 10 ms
0.8 ≤ f/f
≤ 1.2
Nom
stable at machine start-up (f = 0 to f
Increments 0.001 A
24 ms to 29 ms
35 ms to 50 ms
5% of setting value or 1 % Ι
1 % of setting value or 10 ms
45 Hz to 55 Hz at 50 Hz
55 Hz to 65 Hz at 60 Hz
25 Hz to 45 Hz at 50 Hz
30 Hz to 55 Hz at 60 Hz
Increased tolerances
Increments 0.01 s
)
Nom
Technical Data
Nom
265
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