Schweitzer Engineering Laboratories SEL-311B, Инструкция по эксплуатации

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Date Code 20011205 Loss-of-Potential, CCVT Transient Detection, 4-11
Load-Encroachment, and Directional Element Logic
SEL-311B Instruction Manual
The channel IP current-polarized directional element does not use voltage in making direction
decisions, thus a loss-of-potential condition does not disable the element, but rather aids in
enabling it. When the internal enable 32IE is asserted, the channel IP current-polarized
directional element (Figure 4.11) is enabled if enable setting ELOP = Y or Y1 and a loss-of-
potential condition occurs (Relay Word bit ILOP asserts).
Refer to Figure 4.1 and accompanying text for more information on loss-of-potential.
Directional Element Routing
Refer to Figure 4.5 and Figure 4.12.
The directional element outputs are routed to the forward (Relay Word bit 32GF) and reverse
(Relay Word bit 32GR) logic points.
Loss-of-Potential
Note in Figure 4.12 that if all the following are true:
·
enable setting ELOP = Y,
·
a loss-of-potential condition occurs (Relay Word bit LOP asserts),
·
and internal enable 32IE (for channel IP current-polarized directional element) is not
asserted
then the forward logic point (Relay Word bit 32GF) asserts to logical 1, thus, enabling the
residual ground overcurrent elements that are set direction forward. These direction forward
overcurrent elements effectively become nondirectional and provide overcurrent protection
during a loss-of-potential condition.
As detailed in Figure 4.9 and Figure 4.10, voltage-based directional elements are disabled during
a loss-of-potential condition. Thus, the overcurrent elements that are directionally controlled by
these voltage-based directional elements are disabled also. But this disable condition is
overridden if setting ELOP = Y.
Refer to Figure 4.1 and accompanying text for more information on loss-of-potential.
As shown in Figure 3.7 through Figure 3.9, ILOP also disables all ground distance elements.