A-2 BE1-951 Time Overcurrent Characteristic Curves 9328900990 Rev L
Table A-1. 51P, 51N, and 51Q Time Characteristic Curve Constants
Trip Characteristic Constants § Reset †
Curve
Selection
Curve Name
A B C N K R
S1
S, S1, Short Inverse 0.2663 0.03393 1.0000 1.2969 0.0280 0.5000
S2
S2, Short Inverse 0.0286 0.02080 1.0000 0.9844 0.0280 0.0940
L1
L, L1, Long Inverse 5.6143 2.18592 1.0000 1.0000 0.0280 15.750
L2
L2, Long Inverse 2.3955 0.00000 1.0000 0.3125 0.0280 7.8001
D
D, Definite Time 0.4797 0.21359 1.0000 1.5625 0.0280 0.8750
M
M, Moderately Inverse 0.3022 0.12840 1.0000 0.5000 0.0280 1.7500
I1
I, I1, Inverse Time 8.9341 0.17966 1.0000 2.0938 0.0280 9.0000
I2
I2, Inverse Time 0.2747 0.10426 1.0000 0.4375 0.0280 0.8868
V1
V, V1, Very Inverse 5.4678 0.10814 1.0000 2.0469 0.0280 5.5000
V2
V2, Very Inverse 4.4309 0.09910 1.0000 1.9531 0.0280 5.8231
E1
E, E1, Extremely Inverse 7.7624 0.02758 1.0000 2.0938 0.0280 7.7500
E2
E2, Extremely Inverse 4.9883 0.01290 1.0000 2.0469 0.0280 4.7742
A
A, Standard Inverse 0.01414 0.00000 1.0000 0.0200 0.0280 2.0000
B
B, Very Inverse (I
2
t)
1.4636 0.00000 1.0000 1.0469 0.0280 3.2500
C
C, Extremely Inverse (I
2
t)
8.2506 0.00000 1.0000 2.0469 0.0280 8.0000
G
G, Long Time Inverse (I
2
t)
12.1212 0.00000 1.0000 1.0000 0.0280 29.0000
F
Fixed Time ∗
0.0000 1.00000 0.0000 0.0000 0.0280 1.0000
P
Programmable 0 to 600 0 to 25 0 to 1 0.5 to 2.5 0.0280 0 to 30
46
Neg.-Seq. Overcurrent
‡
0 0 2 0.0280 100
∗ Curve F has a fixed delay of one second times the Time Dial setting.
† For integrated reset, append R to the curve name. For example, curve S1 has instantaneous reset.
Curve S1R has integrated reset.
‡ Constant A is variable for the 46 curve and is determined, as necessary, based on system full-load
current setting, minimum pickup, and K factor settings.
§ The programmable curve allows for four significant digits after the decimal place for every variable.
TIME OVERCURRENT CHARACTERISTIC CURVE GRAPHS
Figures A-1 through A-16 illustrate the characteristic curves of the BE1-951 relay. Table A-2 cross-
references each curve to existing electromechanical relay characteristics. Equivalent time dial settings
were calculated at a value of five times pickup. A drawing number is provided in the caption of each
graph.
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