Functionality - ABB REB650 Technical Manual

Section 7
Current protection
7.6.2
7.6.3
7.6.4
118

Functionality

Negative sequence based overcurrent function (DNSPTOC, 46) may be used in power
line applications where the reverse zero sequence source is weak or open, the forward
source impedance is strong and it is desired to detect forward ground faults.
Additionally, it is applied in applications on cables, where zero sequence impedance
depends on the fault current return paths, but the cable negative sequence impedance is
practically constant.
The directional function is current and voltage polarized. The function can be set to
forward, reverse or non-directional independently for each step.
DNSPTOC (46) protects against all unbalanced faults including phase-to-phase faults.
The minimum pickup current of the function must be set to above the normal system
unbalance level in order to avoid unwanted tripping.
Function block
DNSPTOC (46)
I3P* TRIP
V3P* TROC1
BLOCK TROC2
BLKOC1 BFI_3P
ENMLTOC1 PU_OC1
BLKOC2 PU_OC2
ENMLTOC2 DIROC1
DIROC2
CURRENT
VOLTAGE
VIANGLE
ANSI09000125-1-en.vsd
ANSI09000125 V1 EN
Figure 49: DNSPTOC (46) function block
Signals
Table 59: DNSPTOC (46) Input signals
Name Type
I3P GROUP
SIGNAL
V3P GROUP
SIGNAL
BLOCK BOOLEAN
BLKOC1 BOOLEAN
Table continues on next page
Default Description
- Three phase group signal for current inputs
- Three phase group signal for voltage inputs
0 Block of function
0 Block of over current function OC1
1MRK 505 277-UUS C
Technical Manual