Underfrequency Load Shedding
Setting Values for the Function
Minimum voltage 0.300 p.u. to 0.900 p.u. Increments of 0.001 p.u.
Minimum current 0.020 p.u. to 0.200 p.u. Increments of 0.001 p.u.
Power angle -30° to 30° Increments of 1°
Positive power direction inv. to CT neu.pnt sett.
acc. to CT neu.pnt sett.
Threshold value for the df/dt-rising
rate or df/dt-falling rate
0.1 Hz/s to 20.0 Hz/s Increments of 0.1 Hz/s
df/dt measuring window 2 periods to 5 periods Increments of 1 period
df/dt dropout differential 0.02 Hz/s to 0.99 Hz/s Increments of 0.10 Hz/s
f < stabilization counter 1 to 20 Increments of 1
Setting Values for the Stage
Pickup threshold 40.00 Hz to 70.00 Hz Increments of 0.01 Hz
Dropout differential 20 mHz to 2000 mHz Increments of 10 mHz
Time delay 0.00 s to 60.00 s Increments of 0.01 s
Times
Pickup times with stabilization counter = 6
Approx. 85 ms + OOT
135
at 50 Hz
Approx. 80 ms + OOT at 60 Hz
Dropout time Approx. 80 ms + OOT at 50 Hz
Approx. 75 ms + OOT at 60 Hz
Dropout
The greater dropout differential (= | pickup value – dropout value |) of the following 2 criteria
applies:
Dropout
Frequency 0.01 Hz
df/dt-rising rate and df/dt-falling rate 0.1 Hz/s
Voltage V1 105 % of the threshold value
Current I1 105 % of the threshold value at φ ≤ 0
95.23 % of the threshold value at φ > 0
Power angle 1°
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)
Voltage transformer 150 mV sec.
Tolerances
Frequency f<
f
rated
- 0.20 Hz < f < f
rated
+ 0.20 Hz ± 5 mHz at V = V
rated
12.41
135
OOT (Output Operating Time): additional time delay of the output medium used, for example, 5 ms with fast relay
Technical Data
12.41 Underfrequency Load Shedding
SIPROTEC 5, Overcurrent Protection, Manual 1525
C53000-G5040-C017-8, Edition 07.2017
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