ABB REG670 Applications Manual page 370

Section 9
Current protection
364
The characteristic for this OpMode when RCADir = 0° and ROADir = 80° is shown in
figure 193.
IEC06000652 V3 EN
Figure 193: Characteristic for RCADir = 0° and ROADir = 80°
DirMode is set Forward or Reverse to set the direction of the operation for the
directional function selected by the OpMode.
All the directional protection modes have a residual current release level setting
INRel> which is set in % of IBase. This setting should be chosen smaller than or equal
to the lowest fault current to be detected.
All the directional protection modes have a residual voltage release level setting
UNRel> which is set in % of UBase. This setting should be chosen smaller than or
equal to the lowest fault residual 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 earth faults
correctly. The setting shall be much shorter than the set trip delay. In case of
intermittent earth 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 tReset even though the fault current has dropped below the set value.
The characteristic angle of the directional functions RCADir is set in degrees. RCADir
is normally set equal to 0° in a high impedance earthed network with a neutral point
resistor as the active current component is appearing out on the faulted feeder only.
RCADir is set equal to -90° in an isolated network as all currents are mainly capacitive.
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
RCADir = 0º
ROADir = 80º
Operate area
3I
0
-3U
IEC06000652-3-en.vsd
1MRK 502 071-UEN -
0
Application manual