Schweitzer Engineering Laboratories SEL-421-4 - Table 5.19 Fault Location Triggering Elements

5.23
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Functions
Fault Location
Fault Location
The SEL-421 computes distance to fault from data stored in the event reports.
The relay calculates distance to fault upon satisfaction of all four of the following
conditions:
➤ The fault locator is enabled, setting EFLOC := Y.
➤ A single-pole open condition does not exist (i.e., Relay Word bit
SPOA, SPOB, and SPOC equal logical 0).
➤ A phase-distance, ground-distance, residual-ground overcurrent,
negative-sequence, or time-overcurrent element picks up no later
than 15 cycles after the event report trigger.
➤ The fault duration is greater than one cycle, as determined by the
previously listed asserted protection element(s).
The relay calculates distance to fault in per unit of the positive-sequence line
impedance, Z
1
. Use the relay setting LL, Line Length, to determine the units that
the relay reports for the distance to a fault. For example, if a fault occurs at the
midpoint of the protected line and you set LL to 126 for a line length of 126 kilo-
meters, the result of the relay distance-to-fault calculation is 63.
Distance-to-fault calculation results range from –999.99 to 999.99. If the calcula-
tion cannot be determined (e.g., insufficient information) or if the result is outside
the specified range, the relay reports the fault location as
$$$$.$$.
The relay provides an analog fault location value from the most recent event
report, labeled FLOC.
The relay specifies fault type along with the distance to fault. The fault type can
be one of the types listed in Table 5.20.
Time Error Correction Preload Value
TECORR = 2.250 s
Relay Word Elements
LOADTE = 0, STALLTE = 0, FREQOK = 1
Accumulated Time Error
TE = -5.862 s
==>
Figure 5.16 Sample TEC n Command Response (Continued)
Table 5.19 Fault Location Triggering Elements
Fault Type Protection Element
Ground Faults Z1G–Z5G
67G1–67G4
67Q1–67Q4
51S1–51S3
a
a
Corresponding group setting 51S k O must be set to 3I2L or 3I0L (k = 1–3).
Phase Faults Z1P–Z5P
67Q1–67Q4
51S1–51S3
b
b
Corresponding group setting 51S k O must be set to IAL, IBL, ICL, I1L, 3I2L, or IMAXL (k = 1–3).