ABB RELION 620 Series Technical Manual page 355

1MAC504801-IB E
620 series ANSI
Technical Manual
a negative value if operating signal IG or IN leads the polarizing quantity
–VG or –VN, respectively.
Table 285: Recommended Characteristic angle setting for different network
Type of network
Compensated network
Solidly grounded network
Isolated network
The Characteristic angle setting is adjusted to the operation according to the method of
neutral-point grounding, so that in an isolated network Characteristic angle is -90° and in
a compensated network 0°. In addition, Characteristic angle can be changed via the
control signal RCA_CTL, in which case the alternatives are -90° and 0°. The operation of
the RCA_CTL input depends on the Characteristic angle setting.
The Peterson coil or the grounding resistor may be temporarily out of operation. To keep
the protection scheme selective, it is necessary to update the Characteristic angle settings
accordingly. This is done with an auxiliary input in the relay which receives a signal from
an auxiliary switch of the disconnector of the Peterson coil in compensated networks or of
the grounding resistor in grounded network as a result the Characteristic angle is set
automatically to suit the grounding method.
Table 286: Characteristic angle control for the RCA_CTL condition
Characteristic angle Setting
-90°
0°
Low-level blocking
For a reliable operation, signal levels should be greater than the minimum level. If they are
not greater than the minimum level, Timer is blocked.
In the "Neg. seq. volt." polarization selection using Pol signal Sel, if the amplitude of the
negative-sequence current is greater than the Min trip current value and the negative-
sequence voltage amplitude is greater than the Min trip voltage value, the enabling signal
is sent to Timer.
In the "Measured VG" or "Calculated VN" polarization selection using Pol signal Sel, if
the amplitude of the residual current is greater than the Min trip current value and residual
voltage amplitude is greater than the Min trip voltage value, the enabling signal is sent to
Timer.
Characteristic angle recommended
0°
+60°
-90°
RCA_CTL=FALSE
Characteristic angle =-90°
Characteristic angle = 0°
Section 4
Protection functions
RCA_CTL=TRUE
Characteristic angle = 0°
Characteristic angle =-90°
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