Negative Sequence Based Overcurrent Function Dnsptoc (46) - ABB REC650 Applications Manual

1MRK 511 286-UUS A
6.12
6.12.1
6.12.2
6.12.3
Application manual
Negative sequence based overcurrent function
DNSPTOC (46)
Identification
Function description
Negative sequence based overcurrent
function
Application
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. Both steps are provided
with a settable definite time delay.
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 inadvertent tripping.
Setting guidelines
Below is an example of Negative sequence based overcurrent function (DNSPTOC ,46)
used as a sensitive ground-fault protection for power lines. The following settings must be
done in order to ensure proper operation of the protection:
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(VBase) and (SBase).
IEC 61850 IEC 60617
identification identification
DNSPTOC
3I2>
IEC09000132 V2 EN
Section 6
Current protection
ANSI/IEEE C37.2
device number
46
149