Overcurrent Protection, Ground
Stage with Definite-Time Characteristic Curve
Setting Values
Method of measurement Fundamental component
RMS value
–
Threshold value
50
1 A @ 50 and 100 Irated 0.010 A to 35.000 A Increments of 0.001 A
5 A @ 50 and 100 Irated 0.05 A to 175.00 A Increments of 0.01 A
1 A @ 1.6 Irated 0.001 A to 1.600 A Increments of 0.001 A
5 A @ 1.6 Irated 0.002 A to 8.000 A Increments of 0.001 A
Dropout ratio 0.90 to 0.99 Increments of 0.01
Time delay 0.00 s to 60.00 s Increments of 0.01 s
Dropout delay 0.00 s to 60.00 s Increments of 0.01 s
Dropout
The greater dropout differential (= | pickup value – dropout value |) of the following 2 criteria
applies:
Dropout differential derived from the parameter Dropout ratio
If this parameter is not available, a dropout ratio of 95 % applies for overcurrent and of 105 % for undercur-
rent functionality.
Minimum absolute dropout differential
Protection-class current transformer 15 mA sec. (I
rated
= 1 A) or
75 mA sec. (I
rated
= 5 A)
Instrument current transformer 0.5 mA sec. (I
rated
= 1 A) or
2.5 mA sec. (I
rated
= 5 A)
Times
Operate time with time delay = 0 ms
Approx. 25 ms + OOT
51
at 50 Hz
Approx. 22 ms + OOT at 60 Hz
Extension of the operate time during operation with
transformer inrush-current detection
Approx. 10 ms
Dropout time Approx. 20 ms + OOT
Frequency Operating Range
0.9 ≤ f/f
rated
≤ 1.1 According to specified tolerances
10 Hz ≤ f < 0.9 f
rated
1.1 f
rated
< f ≤ 80 Hz
Slightly expanded tolerances
f < 10 Hz
f > 80 Hz
Active
11.9
11.9.1
50
If you have selected the method of measurement = RMS value, do not set the threshold value under 0.1 l
rated,sec
.
51
OOT (Output Operating Time): additional delay of the output medium used, see Chapter 11.1.4 Relay Outputs
Technical Data
11.9 Overcurrent Protection, Ground
SIPROTEC 5, High-Voltage Bay Controller, Manual 1133
C53000-G5040-C015-A, Edition 05.2018
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