Technical Data
4.15 Ground Fault Detection (Sensitive/Insensitive)
SIPROTEC, 7SK80, Manual
E50417-G1140-C344-A5, Release date 11.2012
392
Ground Fault Pickup for All Types of Ground Faults (Inverse Time Characteristic)
Influencing Variables
User-defined characteristic (defined by a maximum of 20 value pairs of current and time delay in direction
measurement method "cos phi and sin phi")
Pickup current 51Ns
for sensitive 1 A transformer
for sensitive 5 A transformer
for normal 1 A transformer
for normal 5-A transformer
0.001 A to 1.400 A
0.005 A to 7.000 A
0.05 A to 4.00 A
0.25 A to 20.00 A
Increments
0.001 A
Increments
0.005 A
Increments
0.01 A
Increments
0.05 A
Time multiplier T
51Ns
0.10 s to 4.00 s or ∞ (disabled) Increments 0.01
s
Pickup threshold Approx. 1.10 · I
51Ns
Dropout ratio Approx. 1.05 · I
51Ns
for I
51Ns
> 50 mA
Measurement tolerance
sensitive
non-sensitive
3 % of setting value or 1 mA at I
Nom
= 1A or 5mA at I
Nom
=
5A
for setting values < 10 mA approx. 20 %
3 % of setting value or 15 mA for I
Nom
= 1 A or 75 mA for I
Nom
= 5 A
Operating time tolerance in linear range 7 % of reference (calculated) value for 2 ≤ I/I
51Ns
≤ 20 + 2 %
current tolerance, or 70 ms
Auxiliary DC voltage in range
0,8 ≤ V
Aux
/V
AuxNom
≤ 1.15
1%
Temperature in range
–5 °C (41 °F) ≤ Θ
amb
≤ 55 °C (131 °F)
0.5 %/10 K
Frequency in range of 25 Hz – 70 Hz
Frequency in range of 0.95 ≤ f/f
Nom
≤ 1.05 (f
Nom
= 50 Hz
or 60 Hz)
1%
Frequency outside range 0.95 ≤ f/f
Nom
≤ 1.05 Increased tolerances
Harmonics
- up to 10 % 3rd harmonic
- up to 10 % 5th harmonic
1%
1%
Note: When using the sensitive transformer, the linear range of the measuring input for sensitive ground fault
detection is from 0.001 A to 1.6 A or 0.005 A to 8.0 A, depending on parameter 205 CT SECONDARY. The
function is however still preserved for larger currents.
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