ABB REC650 User Manual

6.12.2 Functionality
Negative sequence based overcurrent function DNSPTOC is typically used as
sensitive earth-fault protection of power lines, where incorrect zero sequence
polarization may result from mutual induction between two or more parallel lines.
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 protects against all unbalanced faults including phase-to-phase faults. The
minimum start current of the function must be set to above the normal system
unbalance level in order to avoid unwanted operation.
6.12.3 Function block
DNSPTOC
I3P*
U3P*
BLOCK
BLKOC1
ENMLTOC1
BLKOC2
ENMLTOC2
TRIP
TROC1
TROC2
START
STOC1
STOC2
DIROC1
DIROC2
CURRENT
VOLTAGE
UIANGLE
IEC09000125-1-en.vsd
IEC09000125 V1 EN
Figure 67: DNSPTOC function block
6.12.4 Signals
Table 105: DNSPTOC Input signals
Name
Type Default Description
I3P GROUP
SIGNAL
- Three phase group signal for current inputs
U3P GROUP
SIGNAL
- Three phase group signal for voltage inputs
BLOCK BOOLEAN 0 Block of function
BLKOC1 BOOLEAN 0 Block of over current function OC1
ENMLTOC1 BOOLEAN 0 Enable signal for current multiplier - step1 (OC1)
BLKOC2 BOOLEAN 0 Block of over current function OC2
ENMLTOC2 BOOLEAN 0 Enable signal for current multiplier - step 2 (OC2)
1MRK 511 287-UEN A Section 6
Current protection
153
Technical manual

ABB REC650 Specifications

General

Brand	ABB
Model	REC650
Category	Control Unit
Language	English