ABB Relion 670 Series Applications Manual page 168

Section 7
Current protection
DirMode is set Forward or Reverse to set the direction of the operation for the directional function
selected by the
All the directional protection modes have a residual current release level setting
set in % of
be detected.
All the directional protection modes have a residual voltage release level setting
set in % of
voltage to be detected.
tDef is the definite time delay, given in s, for the directional residual current protection.
tReset is the time delay before the definite timer gets reset, given in s. With a tReset time of few
cycles, there is an increased possibility to clear intermittent ground faults correctly. The setting
shall be much shorter than the set trip delay. In case of intermittent ground faults, the fault
current is intermittently dropping below the set value during consecutive cycles. Therefore the
definite timer should continue for a certain time equal to
dropped below the set value.
The characteristic angle of the directional functions
set equal to 0° in a high impedance grounded network with a neutral point resistor as the active
current component is appearing out on the faulted feeder only.
isolated network as all currents are mainly capacitive.
ROADir is Relay Operating Angle. ROADir is identifying a window around the reference direction in
order to detect directionality.
RCADir the function is blocked. The setting can be used to prevent unwanted operation for
from
non-faulted feeders, with large capacitive ground fault current contributions, due to CT phase
angle error.
INCosPhiPU is the operate current level for the directional function when OpModeSel is set
3I0Cosfi . The setting is given in % of IBase . The setting should be based on calculation of the
active or capacitive ground fault current at required sensitivity of the protection.
SN_PU is the operate power level for the directional function when OpModeSel is set 3I03V0Cosfi .
The setting is given in % of
capacitive ground fault residual power at required sensitivity of the protection.
The input transformer for the Sensitive directional residual over current and power protection
function has the same short circuit capacity as the phase current transformers. Hence, there is no
specific requirement for the external CT core, i.e. any CT core can be used.
If the time delay for residual power is chosen the delay time is dependent on two setting
parameters.
The time delay will follow the following expression:
=
t
inv
3I 3V cos (measured)
EQUATION2030-ANSI V1 EN-US
INDirPU is the operate current level for the directional function when OpModeSel is set 3I0 and fi .
The setting is given in % of
current at required sensitivity of the protection.
162
OpModeSel .
IBase . This setting should be chosen smaller than or equal to the lowest fault current to
VBase . This setting should be chosen smaller than or equal to the lowest fault residual
ROADir is set in degrees. For angles differing more than ROADir
SBase . The setting should be based on calculation of the active or
SRef is the reference residual power, given in % of SBase . TDSN is the time multiplier.
×
TDSN Sref
× × j
0 0
IBase . The setting should be based on calculation of the ground fault
tReset even though the fault current has
RCADir is set in degrees. RCADir is normally
RCADir is set equal to -90° in an
1MRK 511 358-UUS A
INRelPU which is
VNRelPU which is
(Equation 59)
Application manual