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

Section 8
Current protection
³
I 1
step3
EQUATION1204 V4 EN-US
where:
I
step2
Step 4
This step normally has non-directional function and a relatively long time delay. The task for
step 4 is to detect and initiate trip for earth faults with large fault resistance, for example tree
faults. Step 4 shall also detect series faults where one or two poles, of a breaker or other
switching device, are open while the other poles are closed.
Both high resistance earth faults and series faults give zero-sequence current flow in the
network. Such currents give disturbances on telecommunication systems and current to earth.
It is important to clear such faults both concerning personal security as well as risk of fire.
The current setting for step 4 is often set down to about 100 A (primary 3I
applications definite time delay in the range 1.2 - 2.0 s is used. In other applications a current
dependent inverse time characteristic is used. This enables a higher degree of selectivity also
for sensitive earth-fault current protection.
8.5 Sensitive directional residual overcurrent and power
protection SDEPSDE
8.5.1

Identification

Function description
Sensitive directional residual over
current and power protection
8.5.2

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.
154
3I
0
× ×
.2 I
step2
3I
02
is the chosen current setting for step 2 on the faulted line.
· 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
IEC 61850 IEC 60617
identification identification
SDEPSDE -
1MRK 505 363-UEN A
(Equation 101)
M15282-177 v4
). In many
0
SEMOD171436-1 v4
SEMOD172025-2 v4
ANSI/IEEE C37.2
device number
67N
SEMOD171959-4 v11
Application manual