Date Code 20011205
Loss-of-Potential, CCVT Transient Detection,
4-23
Load-Encroachment, and Directional Element Logic
SEL-311A Instruction Manual
then the zero-sequence voltage-polarized directional element (V = zero-sequence voltage-
polarized directional element; see Figure 4.10) provides directional control for the ground
distance and residual ground overcurrent elements all the time.
Setting ORDER can be set with any element combination (e.g., ORDER = IQV, ORDER = QVI,
ORDER = IV, ORDER = VQ, ORDER = I, ORDER = Q).
Z2F—Forward Directional Z2 Threshold
Setting Range:
-64.00 to 64.00
W
secondary (5 A nominal phase current inputs, IA, IB, IC)
-320.00 to 320.00
W
secondary (1 A nominal phase current inputs, IA, IB, IC)
Z2F is used to calculate the Forward Threshold for the negative-sequence voltage-polarized
directional elements (see Figure 4.9 and Figure 4.14).
If configuration setting E32 = Y, setting Z2F (negative-sequence impedance) is calculated by the
user and entered by the user.
Z2F Set Automatically
If configuration setting E32 = AUTO, setting Z2F (negative-sequence impedance) is calculated
automatically, using the positive-sequence line impedance magnitude setting Z1MAG as follows:
Z2F = Z1MAG/2
(
Ω
secondary)
50QFP—Forward Directional Negative-Sequence Current Pickup
Setting Range:
0.25–5.00 A secondary (5 A nominal phase current inputs, IA, IB, IC)
0.05–1.00 A secondary (1 A nominal phase current inputs, IA, IB, IC)
The 50QFP setting (3I
2
current value) is the pickup for the forward fault detector 50QF of the
negative-sequence voltage-polarized directional elements (see Figure 4.6). Ideally, the setting is
above normal load unbalance and below the lowest expected negative-sequence current
magnitude for unbalanced forward faults.
50QFP Set Automatically
If configuration setting E32 = AUTO, setting 50QFP is set automatically at:
50QFP = 0.50 A secondary (5 A nominal phase current inputs, IA, IB, IC)
50QFP = 0.10 A secondary (1 A nominal phase current inputs, IA, IB, IC)
Summary of Contents for SEL-311A
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