Sel 421 - Page 58

U.1.16
SEL-421 Relay User’s Guide Date Code 20090715
Introduction and Specifications
Specifications
Reporting Functions
High-Resolution Data
Rate: 8000 samples/second
4000 samples/second
2000 samples/second
1000 samples/second
Output Format: Binary COMTRADE
Note: Per IEEE Standard Common Format for Transient Data
Exchange (COMTRADE) for Power Systems, IEEE C37.111–
1999
Event Reports
Storage: 35 quarter-second events or
24 half-second events
Maximum Duration: Record events as long as 5 seconds
Resolution: 8- or 4-samples/cycle
Event Summary
Storage: 100 summaries
Breaker History
Storage: 128 histories
Sequential Events Recorder
Storage: 1000 entries
Trigger Elements: 250 relay elements
Processing Specifications
AC Voltage and Current Inputs
8000 samples per second, 3 dB low-pass analog filter cut-off
frequency of 3000 Hz.
Digital Filtering
Full-cycle cosine and half-cycle Fourier filters after low-pass
analog and digital filtering.
Protection and Control Processing
8 times per power system cycle
Synchrophasors
Maximum data rate in messages per second
IEEE C37.118 protocol: 60 (nominal 60 Hz system)
50 (nominal 50 Hz system)
SEL Fast Message
protocol:
20 (nominal 60 Hz system)
10 (nominal 50 Hz system)
Control Points
32 remote bits
32 local control bits
32 latch bits in protection logic
32 latch bits in automation logic
Relay Element Pickup Ranges and Accuracies
Mho Phase Distance Elements
Zones 1–5 Impedance Reach
Setting Range
5 A Model: OFF, 0.05 to 64 Ω secondary,
0.01 Ωsteps
1 A Model: OFF, 0.25 to 320 Ω secondary,
0.01 Ω steps
Sensitivity
5 A Model: 0.5 A
P-P
secondary
1 A Model: 0.1 A
P-P
secondary
(Minimum sensitivity is controlled
by the pickup of the supervising
phase-to-phase overcurrent elements
for each zone.)
Accuracy (Steady State): ±3% of setting at line angle for SIR
(source-to-line impedance ratio) < 30
±5% of setting at line angle for
30 ≤SIR ≤ 60
Zone 1 Transient
Overreach:
<5% of setting plus steady-state
accuracy
SEL-421-0 and
SEL-421-3 Maximum
Operating Time: 0.8 cycle at 70% of reach and SIR = 1
SEL-421-1 and
SEL-421-2 Maximum
Operating Time: 1.5 cycle at 70% of reach and SIR = 1
Mho Ground Distance Elements
Zones 1–5 Impedance Reach
Mho Element Reach
5 A Model: OFF, 0.05 to 64 Ω secondary,
0.01 Ω steps
1 A Model: OFF, 0.25 to 320 Ω secondary,
0.01 Ωsteps
Sensitivity
5 A Model: 0.5 A secondary
1 A Model: 0.1 A secondary
(Minimum sensitivity is controlled
by the pickup of the supervising
phase and residual overcurrent
elements for each zone.)
Accuracy (Steady State): ±3% of setting at line angle for SIR
<30
±5% of setting at line angle for
30 ≤SIR ≤ 60
Zone 1 Transient
Overreach:
<5% of setting plus steady-state
accuracy
SEL-421-0 and
SEL-421-3 Maximum
Operating Time: 0.8 cycle at 70% of reach and SIR = 1
SEL-421-1 and
SEL-421-2 Maximum
Operating Time: 1.5 cycle at 70% of reach and SIR = 1
Quadrilateral Ground Distance Elements
Zones 1–5 Impedance Reach
Quadrilateral Reactance Reach
5 A Model: OFF, 0.05 to 64 Ω secondary,
0.01 Ω steps
1 A Model: OFF, 0.25 to 320 Ω secondary,
0.01 Ω steps
Quadrilateral Resistance Reach
5 A Model: OFF, 0.05 to 50 Ω secondary, 0.01 Ω
steps
1 A Model: OFF, 0.25 to 250 Ω secondary, 0.01 Ω
steps
Courtesy of NationalSwitchgear.com