Date Code 20020426 Loss-of-Potential, Load Encroachment, and Directional Element Logic 4-33
SEL-351-5, -6, -7 Instruction Manual
If a level direction setting (e.g., DIR1) is set:
DIR1 = N (nondirectional)
then the corresponding Level 1 directional control outputs in Figure 4.23 and Figure 4.24 assert to
logical 1. The referenced Level 1 overcurrent elements in Figure 4.23 and Figure 4.24 are then
not controlled by the directional control logic.
If group setting VNOM = OFF, then the directional control outputs in Figure 4.23 and
Figure 4.24 assert to logical 1. This effectively makes the phase and negative-sequence elements
nondirectional.
See the beginning of following subsection Directional Control Settings for a discussion of the
operation of level direction settings DIR1 through DIR4 when the directional control enable
setting E32 is set to E32 = N.
In some applications, level direction settings DIR1 through DIR4 are not flexible enough in
assigning the desired direction for certain overcurrent elements. Subsection Directional Control
Provided by Torque Control Settings at the end of this section describes how to avoid this
limitation for special cases.
Figure 4.20: Negative-Sequence Voltage-Polarized Directional Element for Negative-
Sequence and Phase Overcurrent Elements
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