Date Code 20010625
Loss-of-Potential, CCVT Transient Detection,
4-27
Load-Encroachment, and Directional Element Logic
SEL-311L Instruction Manual
a0 Set Automatically
If configuration setting E32 = AUTO, setting a0 is set automatically at:
a0 = 0.1
For setting a0 = 0.1, the zero-sequence current (I
0
) magnitude has to be greater than 1/10 of the
positive-sequence current (I
1
) magnitude in order for the zero-sequence voltage-polarized and
channel IP current-polarized directional elements to be enabled (
1
0
I
•
1
.
0
I
>
).
Z0F—Forward Directional Z0 Threshold
Z0R—Reverse Directional Z0 Threshold
Setting Range:
-64.00 to 64.00
8
secondary (5 A nominal phase current inputs, IA, IB, IC)
-320.00 to 320.00
8
secondary (1 A nominal phase current inputs, IA, IB, IC)
If preceding setting ORDER does not contain V (no zero-sequence voltage-polarized directional
element is enabled), then settings Z0F and Z0R are not made or displayed.
Z0F and Z0R are used to calculate the Forward and Reverse Thresholds, respectively, for the
zero-sequence voltage-polarized directional elements (see Figure 4.10).
If configuration setting E32 = Y, settings Z0F and Z0R (zero-sequence impedance values) are
calculated by the user and entered by the user, but setting Z0R must be greater in value than
setting Z0F by 0.1
8
(5A nominal) or 0.5
8
(1A nominal).
Z0F and Z0R Set Automatically
If configuration setting E32 = AUTO, settings Z0F and Z0R (zero-sequence impedance values)
are calculated automatically, using the zero-sequence line impedance magnitude setting Z0MAG
as follows:
Z0F = Z0MAG/2
(
8
secondary)
Z0R = Z0MAG/2 + 0.1
(
8
secondary; 5A nominal)
Z0R = Z0MAG/2 + 0.5
(
8
secondary; 1A nominal)
E32IV—SEL
OGIC
Control Equation Enable
Refer to Figure 4.7.
SEL
OGIC
control equation setting E32IV must be asserted to logical 1 to enable the zero-
sequence voltage-polarized and channel IP current-polarized directional elements for directional
control of ground distance and residual ground overcurrent elements.
Most often, this setting is set directly to logical 1:
E32IV = 1
(numeral 1)
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