Schweitzer Engineering Laboratories SEL-311L, Instruction Manual, Page: 112 / 734

3-58 Line Current Differential, Distance, Out-of-Step, Overcurrent, Date Code 20011112
Voltage, Synchronism Check, and Frequency Elements
SEL-311L Instruction Manual
Settings Ranges
Setting range for pickup settings 50G1P through 50G4P:
OFF, 0.25–100.00 A secondary (5 A nominal phase current inputs, IA, IB, IC)
OFF, 0.05–20.00 A secondary (1 A nominal phase current inputs, IA, IB, IC)
Setting range for definite-time settings 67G1D through 67G4D:
0.00–16000.00 cycles, in 0.25-cycle steps
Accuracy
Pickup:
±
0.05 A secondary and
±
3% of setting (5 A nominal phase current inputs, IA, IB, IC)
±
0.01 A secondary and
±
3% of setting (1 A nominal phase current inputs, IA, IB, IC)
Timer:
±
0.25 cycles and
±
0.1% of setting
Transient Overreach:
±
5% of setting
Pickup and Reset Time Curves
See Figure 3.43 and Figure 3.44.
Negative-Sequence Instantaneous/Definite-Time Overcurrent Elements
IMPORTANT : See Appendix F for information on setting negative-sequence overcurrent
elements.
Four levels of negative-sequence instantaneous/definite-time overcurrent elements are available.
The different levels are enabled with the E50Q enable setting, as shown in Figure 3.46.
To understand the operation of Figure 3.46, follow the explanation given for Figure 3.42 in the
preceding
Phase Instantaneous/Definite-Time Overcurrent Elements subsection, substituting
negative-sequence current 3I
2
[3I
2
= I
A
+ a
2
• I
B
+ a • I
C
(ABC rotation), 3I
2
= I
A
+ a
2
• I
C
+ a • I
B
(ACB rotation), where a = 1
∠
120° and a
2
= 1
∠
-120°] for phase currents and substituting like
settings and Relay Word bits.
In Figure 3.46, Levels 1 and 2 67Q n elements have directional controls fixed forward. Levels 3
and 4 have selectable forward and reverse directional controls. See Figure 4.14 in Section 4:
Loss-of-Potential, CCVT Transient Detection, Load-Encroachment, and Directional Element
Logic
for more information on this optional directional control.
In cases where the SEL-311L Relay is applied without potentials VA, VB, and VC, use the
Negative-sequence instantaneous/definite-time overcurrent elements in nondirectional mode by
setting ORDER = OFF. For more details, refer to Figure 3.46 and
Section 4: Loss-of-Potential,
CCVT Transient Detection, Load-Encroachment, and Directional Element Logic .