ABB RET670 - Setting Guidelines

In the pilot channel blocking scheme a fault inception detected by a fast acting change
detector is used to send a block signal to the remote end in order to block an
overreaching zone. If the fault is later detected as a forward fault the earlier sent
blocking signal is stopped.
The blocking scheme is very dependable because it will operate for faults anywhere on
the protected line if the communication channel is out of service. Conversely, it is less
secure than permissive schemes because it will trip for external faults within the reach
of the tripping function if the communication channel is out of service. Inadequate
speed or dependability can cause spurious tripping for external faults. Inadequate
security can cause delayed tripping for internal faults.
ZSMGAPC function also includes functionality for blocking the sample based distance
protection due to high SIR. SIR directly influences the fault voltage level for a given
voltage level, and this is the major factor that affects the severity of CVT transients.
Therefore, in cases where the SIR value is too high, further filtering of the measured
signals will be needed.
3.6.7.2 Setting guidelines
IBase: IBase is normally set to the current value of the primary winding of the CT, but
can also be set to the rated current of the bay. IBase shall be adapted to the actual
application.
VBase: VBase is set to the voltage value of the primary winding of the VT. It is by
default set to 400 kV and shall be adapted to the actual application.
PilotMode: Set PilotMode to On when pilot scheme is to be used. In this mode fault
inception function will send a block signal to remote end to block the overreaching
zones, when operated.
DeltaI: The setting of DeltaI for fault inception detection is by default set to 10% of
IBase, which is suitable in most cases.
Delta3I0: The setting of the parameter Delta3I0 for fault inception detection is by
default set to 10% of VBase, which is suitable in most cases.
DeltaV: The setting of DeltaV for fault inception detection is by default set to 5% of
IBase, which is suitable in most cases.
Delta3V0: The setting of Delta3V0 for fault inception detection is by default set to 5%
of VBase, which is suitable in most cases.
Zreach: The setting of Zreach must be adopted to the specific application. The setting
is used in the SIR calculation for detection of high SIR.
Section 3 1MRK504116-UUS C
IED application
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Application manual