Date Code 20011205
Distance and Overcurrent Elements
3-15
SEL-311A Instruction Manual
I
NSTANTANEOUS
/D
EFINITE
-T
IME
O
VERCURRENT
E
LEMENTS
Phase Instantaneous/Definite-Time Overcurrent Elements
One phase instantaneous/definite-time overcurrent element is available. It is enabled with the
E50P enable setting, as shown in Figure 3.10.
Phase instantaneous/definite-time overcurrent elements are available for use in any user-defined
tripping or control scheme.
Settings Ranges
Setting range for pickup setting 50P1P:
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)
Setting range for definite-time setting 67P1D:
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 3.10. The pickup
setting is compared to the magnitudes of the individual phase currents I
A
, I
B
, and I
C
. The logic
outputs in Figure 3.10 are Relay Word bits and operate as follows:
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
_
+
_
+
_
+
50P1P
(Setting)
|IA|
|IB|
|IC|
50P1
67P1D
0
67P1TC
(SEL
OGIC
)
67P1
67P1T
DWG: M311A012
E50P = Y
(Setting)
Enabled
Levels
Relay
Word
Bits
Figure 3.10: Phase Instantaneous/Definite-Time Overcurrent Elements
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