9-52
Setting the Relay
Date Code 20010625
SEL-311L Instruction Manual
Set both reset timers to 30 seconds or 1800 cycles.
1
Power System Protection by P.M. Anderson; IEEE Press; 1999; pg 880.
Demand Metering Settings (See Figures 8.13 and 8.15)
Time constant (5, 10, 15, 30, 60 minutes)
DMTC = 60
Phase pickup (OFF, 0.50–16.00 A secondary {5 A nom.};
0.10–3.20 A secondary {1 A nom.})
PDEMP = OFF
Residual ground pickup (OFF, 0.50–16.00 A secondary {5 A nom.};
0.10–3.20 A secondary {1 A nom.})
GDEMP = OFF
Negative-sequence pickup (OFF, 0.50–16.00 A secondary {5 A nom.};
0.10–3.20 A secondary {1 A nom.})
QDEMP = OFF
Demand metering elements are not used in this example. The settings are left at default values.
Other Settings
Minimum trip duration time (4.00–16000.00 cycles in 0.25-cycle steps)
(see Figure 5.4)
TDURD = 9.00
Close failure time delay (OFF, 0.00–16000.00 cycles in 0.25-cycle steps)
(see Figure 6.1)
CFD = 60.00
Three-pole open time delay (0.00–60.00 cycles in 0.25-cycle steps)
(usually set for no more than a cycle; see Figure 5.5)
3POD = 0.5
Open pole option (52, 27)
OPO = 52
Do not use OPO = 27 in an application that requires 87L elements for tripping. OPO = 27 can
compromise logic that manages charging current inrush when a power line is energized.
Load detection phase pickup (OFF, 0.25–100.00A{5 A nom.};
0.05–20.00 A {1 A nom.}) (see Figure 5.5)
50LP = 0.25
Trip Logic Equations (See Figure 5.1)
Direct trip conditions
TR = M1P + Z1G + M3PT + Z3GT +
51PT + 51GT + T51PT + T50P + T51GT +
T50G + OC
Set the unconditional trip equation TR with Zone1 phase and ground distance elements, phase and
ground time overcurrent elements, Zone 3 time delayed elements, and tapped load differential
elements. Zone 1 phase and ground elements provide instantaneous tripping between Stations S
and R, but do not cover the entire length of line from tap t to Station T. Phase and ground time
overcurrent elements provide backup coverage for the entire protected line. Zone 3 elements
provide overreaching time delayed tripping between Stations S and R, but do not cover the entire
length of line from tap t to Station T. T50P provides instantaneous tripping between Stations S and
R, and T. T50G provides instantaneous tripping between Stations S, R, and T. T51PT and T51GT
provide time delayed tripping between Stations S, R, and T.
Direct transfer trip conditions
DTT = 0
Unlatch trip conditions
ULTR = !(50L + 51G)
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