P.3.125
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Fault Location
Figure 3.74 Relay Exchanging TW Peak Information Via 87L
Communications Channel
NOTE:
The TW fault location is
enabled only if EFLOC = Y, ETWFL = Y,
and E87XFMR = N.
Equation 3.65 shows the fault location calculation.
Equation 3.65
The relay calculates traveling wave fault location upon satisfaction of the
following conditions:
➤ EFLOC=Y and ETWFL=Y
➤ E87XFMR = N
➤ 87L Channel configured to 2SS or 2SD
➤ Relay Word bit TSOK needs to be asserted, indicating high-
accuracy IRIG connection
➤ TWFLIF asserted
➤ Availability of the remote peak information
SEL Relay SEL Relay
PKL PKR
Table 3.59 Traveling Wave Fault Location Settings
Name Description Range Default
ETWFL Enable Traveling Wave Fault Location (Y, N) Y, N N
LLUNIT Line length units mi, km mi
TWLL Line length for TW fault location 0.20–1000 100
SCBL Secondary cable length (unit is yards when
LLUNIT is mi., else is meters), TW fault loca-
tion algorithm compensates for secondary CT
cable length
0–2000 150
LPVEL Propagation velocity in pu of speed of light 0.10000–1 0.98000
TWALTI Alternate TW current source SEL
OGIC N/A
TWCOMI Combine currents for TW (Equ. CT Cable Len.)
(Y/N)
Y, N N
TWFLIF Internal fault condition for TWFL (SEL
OGIC Eq.) SELOGIC (COMPRM
OR 87OP)
AND TRIP
where:
TWLL = the line length of the transmission line
TPKL = the time corresponding to the traveling wave captured at
local terminal
TPKR = the time corresponding to the traveling wave captured at
remote terminal
C = 186282.397 mi/sec (because the Line Length Units
[mi,km] = MI) NOTE: If Line Length Units (mi,km) =
KM, use C = 299792.458 km/sec
LPVEL = the propagation velocity in pu of speed of light
FL TWLL 2 TPKL TPKR–+ CLPVEL2=
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