4.10
SEL-311C Relay Instruction Manual Date Code 20060320
Loss-of-Potential, CCVT Transient Detection, Load-Encroachment, and Directional Element Logic
Directional Control for Ground Distance and Residual Ground Overcurrent Elements
Directional
Element Enables
Refer to Figure 4.5, Figure 4.6, and Figure 4.7.
The directional element enables, Relay Word bits 32QGE, 32VE, and 32IE
have the following correspondence to the directional elements:
➤ 32QGE (Negative-sequence voltage-polarized directional
element)
➤ 32VE (Zero-sequence voltage-polarized directional element)
➤ 32IE (Channel IP current-polarized directional element)
Note that Figure 4.6 has extra directional element enable 32QE, which is used
in the logic that controls phase distance elements (see Figure 4.14).
The settings involved with 32QGE, 32VE, and 32IE in Figure 4.6 and
Figure 4.7 (e.g., settings a2, k2, a0) are explained in Directional Control
Settings on page 4.21.
Best Choice Ground
Directional Logic
Refer to Figure 4.5 and Figure 4.8.
Relay Word bits 32QGE, 32VE, and 32IE and setting ORDER are used in the
Best Choice Ground Directional logic in Figure 4.8. The Best Choice Ground
Directional logic determines the order in which the directional element should
be enabled to operate. The ground distance and residual ground overcurrent
elements set for directional control are then controlled by this directional
element.
Directional Elements
Refer to Figure 4.5, Figure 4.9, Figure 4.10, and Figure 4.11.
The enable output of Best Choice Ground Directional logic in Figure 4.8
determines which directional element will run.
Additionally, note that if enable setting ELOP = Y or Y1 and a loss-of-
potential condition occurs (Relay Word bit ILOP asserts), the negative-
sequence voltage-polarized and zero-sequence voltage-polarized directional
elements are disabled (see Figure 4.9 and Figure 4.10).
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:
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