GE T35 - Page 413

CHAPTER 5: SETTINGS GROUPED ELEMENTS
T35 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL 5-211
5
IAC curves
The curves for the General Electric type IAC relay family are derived from the formulae:
Eq. 5-34
where
T = operate time (in seconds)
TDM = Multiplier setting
I = Input current
I
pkp
= Pickup Current setting
A to E = constants defined in the table
t
r
= characteristic constant defined in the table
T
RESET
= reset time in seconds (assuming energy capacity is 100% and RESET is “Timed”)
Table 5-31: GE type IAC inverse time curve constants
Table 5-32: GE type IAC curve trip times
0.80 51.200 21.333 8.000 4.267 2.667 1.829 1.333 1.016 0.800 0.646
1.00 64.000 26.667 10.000 5.333 3.333 2.286 1.667 1.270 1.000 0.808
IEC Short Inverse
0.05 0.153 0.089 0.056 0.044 0.038 0.034 0.031 0.029 0.027 0.026
0.10 0.306 0.178 0.111 0.088 0.075 0.067 0.062 0.058 0.054 0.052
0.20 0.612 0.356 0.223 0.175 0.150 0.135 0.124 0.115 0.109 0.104
0.40 1.223 0.711 0.445 0.351 0.301 0.269 0.247 0.231 0.218 0.207
0.60 1.835 1.067 0.668 0.526 0.451 0.404 0.371 0.346 0.327 0.311
0.80 2.446 1.423 0.890 0.702 0.602 0.538 0.494 0.461 0.435 0.415
1.00 3.058 1.778 1.113 0.877 0.752 0.673 0.618 0.576 0.544 0.518
IAC curve shape A B C D E t
r
IAC Extreme Inverse 0.0040 0.6379 0.6200 1.7872 0.2461 6.008
IAC Very Inverse 0.0900 0.7955 0.1000 –1.2885 7.9586 4.678
IAC Inverse 0.2078 0.8630 0.8000 –0.4180 0.1947 0.990
IAC Short Inverse 0.0428 0.0609 0.6200 –0.0010 0.0221 0.222
Multiplier
(TDM)
Current ( I / I
pickup
)
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
Multiplier
(TDM)
Current ( I / I
pickup
)
1.5 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0