Sel 411L - Table 3.60 Fault Location Triggering Elements

P.3.130
SEL-411L Relay Protection Manual Date Code 20151029
Protection Functions
Fault Location
If the fault appears to be absent from any of the four-line sections adjacent to
the line terminals, each relay assumes that the fault is on the middle-line
section not directly adjacent to any of the line terminals (Section P-Q in
Figure 3.78). By knowing that each section adjacent to the line terminals is
fault-free, the relays can calculate both the voltages and currents at the P and
Q terminals. For example, the T1 relay will calculate the value at its adjacent
tap P as follows.
Equation 3.72
Equation 3.73
Of course, the relays implement Equation 3.72 to account for self-parameters
and mutual parameters of the line.
Subsequently, the T1 relay runs the double-ended fault location algorithm in
Equation 3.68, with the V
P
and I
P
currents as the local currents.
Equation 3.74
If the value from Equation 3.74 is between 0 and 1 pu, the T1 relay reports the
fault on the middle PQ section at the distance m from the P tap.
The relay computes distance to fault from data stored in the event reports for
the impedance-based fault location method. The relay calculates distance to
fault upon satisfaction of all five of the following conditions.
➤ The fault locator is enabled, setting EFLOC := Y.
➤ A single-pole open condition does not exist at the time of
trigger (i.e., Relay Word bit SPO equals logical 0).
➤ A phase distance, ground distance, residual ground
overcurrent, negative-sequence, or time-overcurrent element
picks up no later than 15 cycles after a trigger.
NOTE: The fault location calculations
trigger when either Trip (TR) or Event
Report (ER) equations assert. When
TR asserts, the letter “T” is appended
after the fault type. For example, if the
relay trips on an A-phase-to-ground
fault, the fault type is shown as AG T.
When ER asserts for the same fault
but TR does not assert, then the fault
type is shown without the letter “T,”
i.e., AG. When both TR and ER assert,
the fault type is shown as AG T.
➤ The fault duration is greater than one cycle, as determined by
the previously listed asserted protection element(s).
➤ For networks with a tap point, the relays exchange fault data to
calculate the faulted section. To ensure that all relays receive
the fault data in a timely manner, set report settings PRE, LER,
and SRATE the same in all relays. If these settings are not the
same, the relays may not calculate the faulted section correctly.
V
P
V
T1
Z
T1
I
T1
• –=
I
P
I
T1
I
T4
+=
m
Im V
P
I
DIF
*• 
Im I
P
Z
PQ
I
DIF
*• • 
------------------------------------------------------=
Table 3.60 Fault Location Triggering Elements
Fault Type Protection Element
Ground faults Z1G–Z5G
67G1–67G4
67Q1–67Q4
51S01–51S10
a
87LA, 87LB, 87LC, 87LQ, 87LG
a
Corresponding group setting 51Ok must be set to IxLFM (x = A, B, C, 1), IPLMAX, 3IA2LFM,
3I2L or 3I0L (k = 01–10), 87IxFM (x = A, B, C, 1, Q).
Phase faults Z1P–Z5P
67Q1–67Q4
51S01–51S10
b
87LA, 87LB, 87LC, 87LQ
b
Corresponding group setting 51Ok must be set to IAL, IBL, ICL, I1L, 3I2L, or IMAXL (k = 01–10),
IGLFM, 87IQFM, 87IGFM.