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12.8
Directional Overcurrent Protection, Phases
Stage with Definite-Time Characteristic Curve
12.8.1
Setting Values
Rotation angle of the reference voltage
Directional mode
Method of measurement
Threshold value
Dropout ratio
Time delay
Dropout delay
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
Instrument current transformer
Direction Determination
Type
Forward range
Dropout differential forward/reverse range
Directional sensitivity
51
If you have selected the method of measurement = RMS value, do not set the threshold value under 0.1 l
SIPROTEC 5, Merging Unit 6MU85, Manual
C53000-G5040-C074-1, Edition 01.2020
1 A @ 50 and 100 Irated
51
5 A @ 50 and 100 Irated
1 A @ 1.6 Irated
5 A @ 1.6 Irated
12.8 Directional Overcurrent Protection, Phases
-180° to +180°
Forward
Reverse
Fundamental component
RMS value
0.030 A to 35.000 A
0.15 A to 175.00 A
0.001 A to 1.600 A
0.005 A to 8.000 A
0.90 to 0.99
0.00 s to 60.00 s
0.00 s to 60.00 s
15 mA sec. (I
= 1 A) or
rated
75 mA sec. (I
= 5 A)
rated
0.5 mA sec. (I
= 1 A) or
rated
2.5 mA sec. (I
= 5 A)
rated
With healthy voltages
With voltage memory 2 s
V
±88°
ref,rot
1°
Unlimited for 1 and 2-phase short circuits
Dynamically unlimited, stationary for 3-phase short
circuits
Approx. 13 V phase-to-phase
Technical Data
Increments of 1°
–
–
Increments of 0.001 A
Increments of 0.01 A
Increments of 0.001 A
Increments of 0.001 A
Increments of 0.01
Increments of 0.01 s
Increments of 0.01 s
.
rated,sec
825
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