Technical Data
4.4 Ground Fault Differential Protection in Grounded Systems
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
299
4.4
Ground Fault Differential Protection in Grounded Systems
Pickup Values
Operating Times
Time Delays
Emergency Operation
Frequency Operating Range
Standard Precision of Operational Measured Values
Differential current;
87N L: I-DIFF>
I
Nom
= 1 A
0.10 A to 20.00 A
Increments 0.01 A
I
Nom
= 5 A
0.50 A to 100.00 A
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: I-DIFF> element at 50 Hz
or 60 Hz approx.
minimum 35 ms
typical 37 ms
maximum 40 ms
Dropout times of the I87N L: I-DIFF> element approx.
minimum
30 ms
typical 32 ms
maximum 34 ms
Differential current
5 % of setting value or 1 %
I
Nom
Delay of the 87N L: I-DIFF> element approx.
1 % of setting value or 10 ms
Frequency range
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
Tripping delay
87L Trip Delay
0.00 s to 0.10 s
Increments 0.01 s
Expiry tolerances
1 % of setting value or 10 ms
The set times are pure time delays.
Communication failure
See section „Time Overcurrent Protection“
Operating Range
0.8
≤
f/f
N
≤
1.2
stable at machine startup (f = 0 to f
N
)
The standard accuracy of the operational measured values of the ground fault differential protection of
±
0.5 % of the rated
operational current is ensured up to a transformer error adjustment of 2:1.
