A-2 BE1-50/51B-235/-236
Characteristic Curves
9252000898 Rev —
Inverse Time Functions
Characteristic curves for the inverse and definite time functions are defined by the following equation:
K
BD
C
M
AD
T
N
T
+
+
−
=
Where: T
T
= time to trip in seconds
D = time dial setting
M = multiple of pickup setting
A, B, C, N, K = constants for the particular curve
Characteristic Curve Groups
Either GE IAC or ABB characteristic curve groups are selected through switch SW3-3. (Refer to Figure 2-
2 for the location of SW3.)
Characteristic Curve Constants
Tables A-1 and A-2 list the time characteristic curve constants used by the relay. Constants have been
selected to conform to the characteristics of electromechanical relays over a range of pickup multiples
from 1.3 to 40. Values of the constants are provided for use in PC relay setting applications. Timing
accuracy is
±
1 cycle
±
2% of time to trip.
Table A-1. Time Characteristic Curve Constants with Switch SW3-3 Open (Off)
Curve
Type
Constants
BE
Similar To
Figure
Number
A B C N K R
S ABB
CO-2
A-2 0.2663 0.03393 1.000 1.2969 0.028 0.500
L ABB
CO-5
A-3 5.6143 2.18592 1.000 1.0000 0.028 15.750
D ABB
CO-6
A-4 0.4794 0.21359 1.000 1.5625 0.028 0.875
M ABB
CO-7
A-5 0.3022 0.12840 1.000 0.5000 0.028 1.750
I ABB
CO-8 A-6 8.9341 0.17966 1.000 2.0938 0.028 9.000
V ABB
CO-9
A-7 5.4678 0.10814 1.000 2.0469 0.028 5.500
E ABB
CO-11 A-8 7.7624 0.02758 1.000 2.0938 0.028 7.750
B
BS142-B
∗
A-9 1.4636
0.00000
1.000 1.0469 0.028 3.250
C
BS142-C
∗
A-10 8.2506
0.00000
1.000 2.0469 0.028 8.000
F None†
None 0.0000 1.00000 0.000 0.0000 0.000 1.000
∗
Curves B and C are defined in British Standard BS142 and IEC 255-4 (International
Electrotechnical Commission).
†
Fixed time from 0.1 to 9.9 seconds.
Table A-2. Time Characteristic Curve Constants with Switch SW3-3 Closed (On)
Curve
Type
Constants
BE
Similar To
Figure
Number
A B C N K R
S
GE IAC 55
A-11
0.0286
0.0208 1.000 0.9844 0.028 0.0940
L
GE IAC 66
A-12
2.3955
0.00002 1.000 0.3125 0.028 7.8001
D ABB
CO-6
A-4 0.4797 0.21359 1.000 1.5625 0.028 0.8750
M ABB
CO-7
A-5 0.3022 0.12840 1.000 0.5000 0.028 1.7500
I
GE IAC 51
A-13
0.2747
0.1042 1.000 0.4375 0.028 0.8868
V
GE IAC 53
A-14
4.4309
0.0991 1.000 1.9531 0.028 5.8231
E
GE IAC 77
A-15
4.9883
0.0129 1.000 2.0469 0.028 4.7742
B
BS142-B
∗
A-9 1.4636
0.00000
1.000 1.0469 0.028 3.2500
C
BS142-C
∗
A-10 8.2506
0.00000
1.000 2.0469 0.028 8.0000
F None†
None 0.0000 1.00000 0.000 0.0000 0.000 1.0000
∗
Curves B and C are defined in British Standard BS142 and IEC 255-4 (International
Electrotechnical Commission).
†
Fixed time from 0.1 to 9.9 seconds.
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