ABB REQ650 Applications Manual page 135

1MRK 505 291-UEN A
Application manual
IEC06000652 V3 EN
Figure 65: Characteristic for RCADir = 0° and ROADir = 80°
DirMode is set Forward or Reverse to set the direction of the trip function from the
directional residual current function.
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
if definite time delay is chosen.
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.
The relay open angle ROADir is set in degrees. For angles differing more than
ROADir fromRCADir the function from the protection is blocked. The setting can be
used to prevent unwanted function for non-faulted feeders, with large capacitive
earth-fault current contributions, due to CT phase angle error.
INCosPhi> is the operate current level for the directional function when OpMode is
set 3I0Cosfi. The setting is given in % of IBase. The setting should be based on
calculation of the active or capacitive earth-fault current at required sensitivity of the
protection.
RCADir = 0º
ROADir = 80º
Operate area
3I
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-3U
IEC06000652-3-en.vsd
Section 6
Current protection
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