3.26
SEL-311C Relay Instruction Manual Date Code 20060320
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Instantaneous/Definite-Time Overcurrent Elements
Instantaneous/Definite-Time Overcurrent Elements
Phase Instantaneous/
Definite-Time
Overcurrent Elements
Three levels of phase instantaneous/definite-time overcurrent elements are
available. The different levels are enabled with the E50P enable setting, as
shown in Figure 3.19.
All phase instantaneous/definite-time overcurrent elements are available for
use in any user-defined tripping or control scheme.
Settings Ranges
Accuracy
Pickup Operation
See the phase instantaneous/definite-time overcurrent element logic in
Figure 3.19. The pickup settings for each level (50P1P through 50P3P) are
compared to the magnitudes of the individual phase currents I
A
, I
B
, and I
C
.
The logic outputs in Figure 3.19 are Relay Word bits and operate as follows
(Level 1 example shown):
50P1 = 1 (logical 1), if at least one phase current exceeds the 50P1P setting
50P1 = 0 (logical 0), if no phase current exceeds the 50P1P setting
Ideally, set 50P1P > 50P2P > 50P3P so that overcurrent elements will display
in an organized fashion in event reports (see Figure 3.19 and Table 12.4).
Settings Range Description
Pickup Settings 50P1P–50P3P
OFF, 0.25–100.00 A secondary 5 A nominal phase current inputs, IA, IB, IC
OFF, 0.05–20.00 A secondary 1 A nominal phase current inputs, IA, IB, IC
Definite-Time Settings 67P1D–67P3D
0.00–16000.00 cycles, in 0.25-cycle steps
Pickup
±0.05 A secondary and ±3% of setting
(5 A nominal phase current inputs, IA, IB, IC)
±0.01 A secondary and ±3% of setting
(1 A nominal phase current inputs, IA, IB, IC)
Timer
±0.25 cycles and ±0.1% of setting
Transient Overreach
<5% of setting
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