8.8.3 Setting guidelines
GlobalBaseSel: Selects the global base value group used by the function to define IBase,
VBase and SBase as applicable.
INRelPG: The setting of INRelPG for release of the phase-to-ground loop is by default set
to 20% of IBase. The default setting is suitable in most applications.
The setting must normally be set to at least 10% lower than the setting of 3I0BLK_PPto
give priority to open phase-to-ground loop. INRelPG must be above the normal un-
balance current (3I
0
) that might exist due to un-transposed lines.
The setting must also be set higher than the 3I
0
that occurs when one pole opens in single
pole trip applications.
3I0BLK_PP: The setting of 3I0BLK_PP is by default set to 40% of IBase, which is
suitable in most applications.
I1LowLevel: The setting of the positive current threshold I1LowLevel used in the sequence
based part of the phase selector for identifying three-phase fault, is by default set to 10% of
IBase.
The default setting is suitable in most cases, but must be checked against the minimum
three-phase current that occurs at remote end of the line with reasonable fault resistance.
IMaxLoad: The setting IMaxLoad must be set higher than the maximum load current
transfer during emergency conditions including a safety margin of at least 20%. The
setting is proposed to be according to equation 225:
EQUATION1614 V2 EN
(Equation 225)
where:
1.2 is the security margin against the load current and
ILoad is the maximal load current during emergency conditions.
The current ILoad can be defined according to equation 226.
Section 8 1MRK 506 369-UUS -
Impedance protection
306 Line distance protection REL670 2.2 ANSI
Application manual
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