Schweitzer Engineering Laboratories SEL-311C - Table 4.3 First Entry in ORDER Setting if Ground Quadrilateral Distance Elements Are Used

4.23
Date Code 20060320 Instruction Manual SEL-311C Relay
Loss-of-Potential, CCVT Transient Detection, Load-Encroachment, and Directional Element Logic
Directional Control Settings
Z2F—Forward Directional Z2 Threshold
Z2R—Reverse Directional Z2 Threshold
Setting Range:
–64.00 to 64.00 Ω secondary
(5 A nominal phase current inputs, IA, IB, IC)
–320.00 to 320.00 Ω secondary
(1 A nominal phase current inputs, IA, IB, IC)
Z2F and Z2R are used to calculate the Forward and Reverse Thresholds,
respectively, for the negative-sequence voltage-polarized directional elements
(see Figure 4.9 and Figure 4.14).
If configuration setting E32 = Y, settings Z2F and Z2R (negative-sequence
impedance values) are calculated by the user and entered by the user, but
setting Z2R must be greater in value than setting Z2F by 0.1 Ω (5 A nominal)
or 0.5 Ω (1 A nominal).
Z2F and Z2R Set Automatically
If configuration setting E32 = AUTO, settings Z2F and Z2R (negative-
sequence impedance values) are calculated automatically, using the positive-
sequence line impedance magnitude setting Z1MAG as follows:
Z2F = Z1MAG/2 (Ω secondary)
Z2R = Z1MAG/2 + 0.1 (Ω secondary; 5 A nominal)
Z2R = Z1MAG/2 + 0.5 (Ω secondary; 1 A nominal)
50QFP—Forward Directional Negative-Sequence Current Pickup
50QRP—Reverse 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.
The 50QRP setting (3I
2
current value) is the pickup for the reverse fault
detector 50QR 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 reverse faults.
Table 4.3 First Entry in ORDER Setting
if Ground Quadrilateral Distance Elements Are Used
Setting
XGPOL
First Element of ORDER
IG Q or V
I2 Q