Schweitzer Engineering Laboratories SEL-311L, Instruction Manual, Page: 90 / 734

3-36 Line Current Differential, Distance, Out-of-Step, Overcurrent, Date Code 20011112
Voltage, Synchronism Check, and Frequency Elements
SEL-311L Instruction Manual
compensator distance element measures impedance through the transformer for all
phase faults and will not overreach on ground faults. See
Application Guide
AG96-16: Applying SEL Distance Relays on Lines with Power Transformers or
Open Delta VTs for more information.
•
Blocking reclose on three-phase faults. Relay Word bits MPP n (Zone/Level n phase-
to-phase compensator distance element) and MABC n (Zone/Level n three-phase
compensator distance element) may be used to discriminate between phase-to-phase
and three-phase faults in the SEL
OGIC
control equation 79DTL (drive-to-lockout).
79DTL = MABC2 * !MPP2 …
Note that both three-phase and single-phase compensator-distance elements will
operate for
Phase A-B faults within the protected zone since the three-phase element
uses V
C
mem (V
C
memorized voltage) for polarizing.
Compensator distance and positive-sequence polarized distance may not be applied at the same
time. Select compensator distance with a “C” suffix to the number of zones in the E21P setting
(e.g., 3C is three zones of compensator distance relaying). If EADVS = N and compensator
distance elements are selected, E21MG is set to “N” and hidden. If EADVS = Y, setting E21MG
is visible and the user may apply ground distance relaying along with compensator distance phase
relaying.
Mho Phase Distance Elements (Zones 1–4)
Enable Setting: E21P
Setting range for Mho Phase Distance
Elements (Z1P through Z4P):
OFF, 0.05 to 64
Ω
sec, 0.01
Ω
steps (5 A nominal)
OFF, 0.25 to 320
Ω
sec, 0.01
Ω
steps
(1 A nominal)
Minimum sensitivity is controlled by the pickup of
the supervising phase-to-phase overcurrent
elements for each zone.
Accuracy:
±
5% of setting at line angle for 30
≤
SIR
≤
60
±
3% of setting at line angle for SIR < 30
Transient Overreach: < 5% of setting plus steady state accuracy
Phase-to-Phase Current Fault Detectors (Zones 1–4)
Setting Range for Phase-to-Phase Current
Fault Detectors (50PP1–50PP4):
Note: If setting EADVS = N, settings
50PP2–50PP4 are at minimum
values and are hidden.
0.50–170.00 A
P-P
secondary, 0.01 A steps
(5 A nominal)
0.10–34.00 A
P-P
secondary, 0.01 A steps
(1 A nominal)
Accuracy:
±
0.05 A and ±3% of setting (5 A nominal)
±
0.01 A and ±3% of setting (1 A nominal)
Transient Overreach: < 5% of pickup
Max. Operating Time: See pickup and reset time curves in Figure 3.43
and Figure 3.44.