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3-18
Distance, Overcurrent, Voltage,
Date Code 20011205
and Synchronism Check Elements
SEL-311B Instruction Manual
Settings Ranges
Settings range for pickup settings 50P1P through 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)
Settings range for definite-time settings 67P1D through 67P3D:
0.00–16000.00 cycles, in 0.25-cycle steps
Accuracy
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
Pickup Operation
See the phase instantaneous/definite-time overcurrent element logic in Figure 3.13. 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 3.13 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
= 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 3.13 and Table 12.3).
Summary of Contents for SEL-311B
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