Sensitive Directional Residual Overcurrent And Power Protection Sdepsde; Identification; Application - ABB RELION 650 Series Applications Manual

1MRK 504 158-UEN A
3I
0fault 2
EQUATION1455 V2 EN-US
Where:
lowmar
highmar is a margin to assure fast fault clearance of busbar fault (typical 1.2).
Setting of step 2
The setting of the sensitive step 2 is dependent of the chosen time delay. Often a relatively
long definite time delay or inverse time delay is chosen. The current setting can be chosen very
low. As it is required to detect earth faults in the transformer winding, close to the neutral
point, values down to the minimum setting possibilities can be chosen. However, one must
consider zero-sequence currents that can occur during normal operation of the power system.
Such currents can be due to un-transposed lines.
In case to protection of transformer windings not feeding residual current at external earth
faults a fast lowcurrent step can be acceptable.
7.5 Sensitive directional residual overcurrent and power
protection SDEPSDE
7.5.1

Identification

Function description
Sensitive directional residual over
current and power protection
7.5.2

Application

In networks with high impedance earthing, the phase-to-earth fault current is significantly
smaller than the short circuit currents. Another difficulty for earth fault protection is that the
magnitude of the phase-to-earth fault current is almost independent of the fault location in
the network.
Directional residual current can be used to detect and give selective trip of phase-to-earth
faults in high impedance earthed networks. The protection uses the residual current
component 3I
voltage (-3U
to strict 3I
Directional residual power can also be used to detect and give selective trip of phase-to-earth
faults in high impedance earthed networks. The protection uses the residual power
component 3I
reference residual voltage, compensated with a characteristic angle.
A normal non-directional residual current function can also be used with definite or inverse
time delay.
Application manual
× < <
lowmar I 3I
step1 0fault1
is a margin to assure selectivity (typical 1.2) and
· cos φ, where φ is the angle between the residual current and the residual
0
), compensated with a characteristic angle. Alternatively, the function can be set
0
level with a check of angle φ.
0
· 3U · cos φ, where φ is the angle between the residual current and the
0 0
×
highmar
IEC 61850 IEC 60617
identification identification
SDEPSDE -
Section 7
Current protection
(Equation 34)
SEMOD55591-57 v4
SEMOD171436-1 v4
SEMOD172025-2 v4
ANSI/IEEE C37.2
device number
67N
SEMOD171959-4 v11
111