Dropout
The greater dropout differential (= | pickup value – dropout value |) of the following 2 criteria
applies:
Dropout 95 % of 1.1 ⋅ threshold value
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)
Reset of the Integration Timer
Instantaneous With dropout
Disk emulation Approx. < 0.90 ⋅ threshold value
Operate Curves and Dropout-Time Characteristic Curves according to IEC
Normal inverse: type A See Figure 11-1 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Very inverse: type B
Extremely inverse: type C See Figure 11-2 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Long-time inverse: type B
Short-time inverse
(Only in the advanced stage)
See Figure 11-3 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Operate Curves and Dropout-Time Characteristic Curves according to ANSI/IEEE
Inverse: type C
See Figure 11-4 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Short inverse
Long inverse See Figure 11-5 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Moderately inverse
Very inverse See Figure 11-6 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Extremely inverse
Definite inverse See Figure 11-7 in chapter 11.15.2 Stage with
Inverse-Time Characteristic Curve
Direction Determination
Type
With healthy voltages
With voltage memory 2 s
Forward range V
ref,rot
±88°
Dropout differential forward/reverse range 1°
Directional sensitivity For 1 and 2-phase short circuits: unlimited
For 3-phase short circuits: dynamically unlimited,
stationary
Approx. 13 V phase-to-phase
Technical Data
11.17 Directional Overcurrent Protection, Phases
950 SIPROTEC 5, Low-Impedance Busbar Protection, Manual
C53000-G5040-C019-C, Edition 04.2021
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