ABB RET670 Applications Manual page 466

Section 3
IED application
460
ANSI06000652 V2 EN
Figure 203: 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
INRelPU 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
VNRelPU which is set in % of VBase. 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.
tReset is the reset time for definite time delay, given in s. With a tReset time of several
periods there is increased possibilities to clear intermittent ground-faults correctly. The
setting shall be much shorter than the set trip delay.
The characteristic angle of the directional functions RCADir is set in degrees. RCADir
is normally 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.
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
RCA = 0º
ROA = 80º
Operate area
3I
0
V =-3V
ref
ANSI06000652-2-en.vsd
1MRK504116-UUS C
0
Application manual