ABB Relion 650 Series Applications Manual page 99

1MRK 505 287-UUS B
7.6 Negative sequence based overcurrent function DNSPTOC
(46)
7.6.1 Identification
Function description
Negative sequence based
overcurrent function
7.6.2 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.
7.6.3 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 )
SBase ).
and (
• setting
inverted negative sequence voltage for this angle during the fault
• setting
• setting
directional element will be enabled
• setting
• setting
• setting
installed in the vicinity of this power line
• setting
• setting
• setting
Busbar protection REB650
Application manual
IEC 61850
identification
DNSPTOC
RCADir to value +65 degrees , that is, the negative sequence current typically lags the
ROADir to value 90 degrees
LowVolt_VM to value 2% , that is, the negative sequence voltage level above which the
Operation_OC1 to Enabled
PickupCurr_OC1 to value between 3-10% , (typical values)
tDef_OC1 to insure proper time coordination with other ground-fault protections
DirMode_OC1 to Forward
DirPrinc_OC1 to IcosPhi&V
ActLowVolt1_VM to Block
© Copyright 2013 ABB. All rights reserved
IEC 60617 ANSI/IEEE C37.2
identification device number
46
3I2>
IEC09000132 V2 EN-US
Section 7
Current protection
GUID-66A7DE2F-EBD6-4601-B0F7-2B568968EA33 v1
GUID-F53558B3-4614-4502-82DD-B7BA07FB2723 v1
GUID-CFD34404-5934-41EE-8AAC-A5FD2B9B4E33 v5
GUID-C39F2683-E51B-4B69-B1AF-4C2EDD5C6FBE v4
93