Schweitzer Engineering Laboratories SEL-311L, Инструкция по эксплуатации

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Date Code 20010625 Loss-of-Potential, CCVT Transient Detection, 4-19
Load-Encroachment, and Directional Element Logic
SEL-311L Instruction Manual
Directional Elements
Refer to Figure 4.13, Figure 4.14, and Figure 4.15.
If enable setting ELOP = Y or Y1 and a loss-of-potential condition occurs (Relay Word bit LOP
asserts), the negative-sequence voltage-polarized and positive-sequence voltage-polarized
directional elements and the phase distance elements are disabled by ILOP (see Figure 4.14 and
Figure 4.15).
Refer to Figure 4.1 and accompanying text for more information on loss-of-potential.
The negative-sequence voltage-polarized directional element operates for unbalanced faults while
the positive-sequence voltage-polarized directional element operates for three-phase faults.
Note in Figure 4.15 that the assertion of ZLOAD disables the positive-sequence voltage-polarized
directional element. ZLOAD asserts when the relay is operating in a user-defined load region
(see Figure 4.3).
Directional Element Routing
Refer to Figure 4.13 and Figure 4.14.
The directional element outputs are routed to the forward (Relay Word bit 32QF) and reverse
(Relay Word bit 32QR) logic points.
Loss-of-Potential
Note if both the following are true:
v
Enable setting ELOP = Y,
v
A loss-of-potential condition occurs (Relay Word bit LOP asserts),
then the forward logic points (Relay Word bit 32QF) assert to logical 1, thus enabling elements
that are set direction forward. These direction forward elements effectively become
nondirectional and provide protection during a loss-of-potential condition.
Refer to Figure 4.1 and accompanying text for more information on loss-of-potential.
As shown in Figure 3.29 through Figure 3.31, ILOP also disables all phase distance elements.