GE 750 User Manual

12-
4
750/760 Feeder Management Relay GE Power Management
12.1 TIME OVERCURRENT CURVE CHARACTERISTICS 12 S5 PROTECTION
12
12.1.4 IAC CURVES
The curves for the General Electric type IAC relay family are derived from the formula:
where T = Trip Time (seconds)
M = Multiplier Setpoint
I = Input Current
I
pu
= Pickup Current Setpoint
A, B, C, D, E = Constants
Table 12–5:
IAC CURVE TRIP TIMES (IN SECONDS
)
Graphs of standard time-current curves on 11”
×
17” log-log graph paper are available upon request.
Requests may be placed with our literature department.
Table 12–4: IAC CURVE CONSTANTS
IAC CURVE CONSTANTS A B C D E
IAC EXTREME INVERSE 0.0040 0.6379 0.6200 1.7872 0.2461
IAC VERY INVERSE 0.0900 0.7955 0.1000 -1.2885 7.9586
IAC INVERSE 0.2078 0.8630 0.8000 -0.4180 0.1947
IAC SHORT INVERSE 0.0428 0.0609 0.6200 -0.0010 0.0221
()
()()
TM A
B
C
D
C
E
C
I
I
I
I
I
I
pu
pu pu
=× +
−
+
−
+
−










23
Multiplier Current (I / Ipu )
(M) 1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
IAC EXTREMELY INVERSE
0.5 1.699 0.749 0.303 0.178 0.123 0.093 0.074 0.062 0.053 0.046
1.0 3.398 1.498 0.606 0.356 0.246 0.186 0.149 0.124 0.106 0.093
2.0 6.796 2.997 1.212 0.711 0.491 0.372 0.298 0.248 0.212 0.185
4.0 13.591 5.993 2.423 1.422 0.983 0.744 0.595 0.495 0.424 0.370
6.0 20.387 8.990 3.635 2.133 1.474 1.115 0.893 0.743 0.636 0.556
8.0 27.183 11.987 4.846 2.844 1.966 1.487 1.191 0.991 0.848 0.741
10.0 33.979 14.983 6.058 3.555 2.457 1.859 1.488 1.239 1.060 0.926
IAC VERY INVERSE
0.5 1.451 0.656 0.269 0.172 0.133 0.113 0.101 0.093 0.087 0.083
1.0 2.901 1.312 0.537 0.343 0.266 0.227 0.202 0.186 0.174 0.165
2.0 5.802 2.624 1.075 0.687 0.533 0.453 0.405 0.372 0.349 0.331
4.0 11.605 5.248 2.150 1.374 1.065 0.906 0.810 0.745 0.698 0.662
6.0 17.407 7.872 3.225 2.061 1.598 1.359 1.215 1.117 1.046 0.992
8.0 23.209 10.497 4.299 2.747 2.131 1.813 1.620 1.490 1.395 1.323
10.0 29.012 13.121 5.374 3.434 2.663 2.266 2.025 1.862 1.744 1.654
IAC NORMALLY INVERSE
0.5 0.578 0.375 0.266 0.221 0.196 0.180 0.168 0.160 0.154 0.148
1.0 1.155 0.749 0.532 0.443 0.392 0.360 0.337 0.320 0.307 0.297
2.0 2.310 1.499 1.064 0.885 0.784 0.719 0.674 0.640 0.614 0.594
4.0 4.621 2.997 2.128 1.770 1.569 1.439 1.348 1.280 1.229 1.188
6.0 6.931 4.496 3.192 2.656 2.353 2.158 2.022 1.921 1.843 1.781
8.0 9.242 5.995 4.256 3.541 3.138 2.878 2.695 2.561 2.457 2.375
10.0 11.552 7.494 5.320 4.426 3.922 3.597 3.369 3.201 3.072 2.969
IAC SHORT INVERSE
0.5 0.072 0.047 0.035 0.031 0.028 0.027 0.026 0.026 0.025 0.025
1.0 0.143 0.095 0.070 0.061 0.057 0.054 0.052 0.051 0.050 0.049
2.0 0.286 0.190 0.140 0.123 0.114 0.108 0.105 0.102 0.100 0.099
4.0 0.573 0.379 0.279 0.245 0.228 0.217 0.210 0.204 0.200 0.197
6.0 0.859 0.569 0.419 0.368 0.341 0.325 0.314 0.307 0.301 0.296
8.0 1.145 0.759 0.559 0.490 0.455 0.434 0.419 0.409 0.401 0.394
10.0 1.431 0.948 0.699 0.613 0.569 0.542 0.524 0.511 0.501 0.493

GE 750 Specifications

General

Brand	GE
Model	750
Category	Relays
Language	English