Schweitzer Engineering SEL-351P, Quick Start Manual

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Date Code 990430 Loss-of-Potential, Load Encroachment, and Directional Element Logic 4-29
SEL-351P Manual Técnico
Provided by Torque Control Settings at the end of this section describes how to avoid this
limitation for special cases.
ORDER – Ground Directional Element Priority Setting
Setting Range:
Q Negative-sequence voltage-polarized directional element
V Zero-sequence voltage-polarized, residual-current directional element and zero-
sequence voltage-polarized, neutral-current directional element
OFF No ground directional control
Setting ORDER can be set with any combination of Q and V. The order in which these
directional elements are listed in setting ORDER determines the priority in which they operate to
provide
Best Choice Ground Directional logic control. See Figure SECTION 4: .8.
For example, if setting:
ORDER = QV
then the first listed directional element (Q = negative-sequence voltage-polarized, residual-
current directional element; see Figure SECTION 4: .9) is the first priority directional element to
provide directional control for the neutral ground and residual ground overcurrent elements.
If the zero-sequence voltage-polarized directional element is not operable (i.e., it does not have
sufficient operating quantity as indicated by its internal enable, 32QGE, not being asserted), then
the second listed directional element (V = zero-sequence voltage-polarized, residual-current
directional element; see Figure SECTION 4: .10) provides directional control for the neutral
ground and residual ground overcurrent elements.
If the zero-sequence voltage-polarized, residual-current directional element is not operable (i.e.,
it does not have sufficient operating quantity as indicated by its internal enable, 32VE, not being
asserted), then 32NE asserts according to Figure SECTION 4: .7. In this case, directional
control will be provided for neutral ground overcurrent elements only.
Another example, if setting:
ORDER = V
then the zero-sequence voltage-polarized, residual-current directional element (see
Figure SECTION 4: .10) provides directional control for the neutral ground and residual ground
overcurrent elements. If the zero-sequence voltage-polarized, residual-current directional
element is not operable (i.e., it does not have sufficient operating quantity as indicated by its
internal enable, 32VE, not being asserted), then 32NE asserts according to Figure SECTION 4:
.7. In this case, directional control will be provided for neutral ground overcurrent elements
only.
Setting ORDER can be set with any element combination (e.g., ORDER = VQ, ORDER = Q).