P.3.209
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Selectable Time-Overcurrent Elements (51)
Figure 3.143 IEC Curves C4 and C5
The 51 overcurrent elements of the relay have dynamic pickup (51Pxx) and
time-delay (51TDxx) values. Because these settings can be programmed by
means of protection math variables (PMVs), their actual values cannot be
checked at setting time. To ensure that the pickup and time-delay values are
within their predefined limits, the relay uses a limit check to verify the validity
of setting values. Relay Word bits 51TMxx (time-dial limit check) and
51MMxx (pickup-limit check) are used to indicate a setting that is outside of
the limit check thresholds. If the maximum limit thresholds are exceeded, the
relay uses the maximum limit value. If the minimum limit thresholds are
exceeded, the relay uses the minimum limit value (see Figure 3.144).
EXAMPLE 3.5
W current channel inputs are 5 A nominal …. From relay part number
51O01 := LIMAXM
Therefore 51B101 := 0.25 (lower limit)
And 51B201 := 16.0 (upper limit)
5 A Current Terminal: (Determined by Relay part number and the
operating quantity)
B
1
:= 0.25 and B
2
:= 16.0
W current channel inputs are 1 A nominal …. From relay part number
51O01 := LIMAXM
Therefore 51B101 := 0.05 (lower limit)
And 51B201 := 3.2 (upper limit)
1 A Current Terminal: (Determined by relay part number and the
operating quantity)
B
1
:= 0.05 and B
2
:= 3.2
10
20
30
40
50
60
70
80
90
100
1
2
3
4
5
6
7
8
9
.1
.2
.3
.4
.5
.6
.7
.8
.9
.01
.02
.03
.04
.05
.06
.07
.08
.09
100
123456789.5 .6 .7 .8 .9
90
80
70
60
50
40
30
20
10
Time in Seconds
Multiples of Pickup
0.05
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.20
0.10
0.05
1.00
0.90
0.80
0.70
0.60
0.50
0.40
0.30
.7.6.5
.1
.9.8 1
.4
.2
.3
.5
.6
.8
.7
.9
1
2
3
4
5
7
6
423 765
10
98
40
20
30
70
50
60
80
90
100
50
9
8
10
20
30
40
300
200
100
80
60
70
90
1000
900
800
700
600
500
400
Time in Seconds
Multiples of Pickup
Time in Cycles 60 Hz (50 Hz)
30 (25)
60 (50)
150 (125)
300 (250)
3000 (2500)
600 (500)
1500 (1250)
6000 (5000)
15000 (12500)
30000 (25000)
60000 (50000)
Time in Cycles 60 Hz (50 Hz)
3 (2.5)
6 (5)
15 (12.5)
30 (25)
60 (50)
600 (500)
150 (125)
300 (250)
1500 (1250)
3000 (2500)
6000 (5000)
IEC Long-Time Inverse Curve: C4 IEC Short-Time Inverse Curve: C5
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