GE 845 Instruction Manual page 283

CHAPTER 4: SETPOINTS
MULTIPLIER CURRENT (I/I
pickup
(TDM)
1.5 2.0
IEEE VERY INVERSE
0.5 8.090 3.514
1.0 16.179 7.028
2.0 32.358 14.055
4.0 64.716 28.111
6.0 97.074 42.166
8.0 129.432 56.221
10.0 161.790 70.277
IEEE MODERATELY INVERSE
0.5 3.220 1.902
1.0 6.439 3.803
2.0 12.878 7.606
4.0 25.756 15.213
6.0 38.634 22.819
8.0 51.512 30.426
10.0 64.390 38.032
Table 4-27: ANSI CURVE TRIP TIMES (IN SECONDS)
MULTIPLIER CURRENT (I/Ipickup)
(TDM)
1.5
ANSI EXTREMELY INVERSE
0.5 2.000
1.0 4.001
845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
)
3.0 4.0
1.471 0.899
2.942 1.798
5.885 3.597
11.769 7.193
17.654 10.790
23.538 14.387
29.423 17.983
1.216 0.973
2.432 1.946
4.864 3.892
9.729 7.783
14.593 11.675
19.458 15.567
24.322 19.458
ANSI CURVES
The ANSI time overcurrent curve shapes conform to industry standards and the ANSI
C37.90 curve classifications for extremely, very, and moderately inverse. The ANSI curves
are derived from the following formulae:
Where:
T = operate time (in seconds)
TDM = Multiplier setting
I = input current
I = Pickup Current setting
pickup
A to E = constants
T = reset time in seconds (assuming energy capacity is 100% and RESET is
RESET
"Timed")
t = characteristic constant
r
Table 4-26: ANSI INVERSE TIME CURVE CONSTANTS
ANSI CURVE SHAPE
ANSI Extremely Inverse
ANSI Very Inverse
ANSI Normally Inverse
ANSI Moderately Inverse
2.0 3.0 4.0
0.872 0.330 0.184
1.744 0.659 0.368
5.0 6.0 7.0
0.654 0.526 0.450
1.308 1.051 0.900
2.616 2.103 1.799
5.232 4.205 3.598
7.849 6.308 5.397
10.465 8.410 7.196
13.081 10.513 8.995
0.844 0.763 0.706
1.688 1.526 1.412
3.377 3.051 2.823
6.753 6.102 5.647
10.130 9.153 8.470
13.507 12.204 11.294
16.883 15.255 14.117
A B C
0.0399 0.2294 0.5000
0.0615 0.7989 0.3400
0.0274 2.2614 0.3000
0.1735 0.6791 0.8000
5.0 6.0 7.0
0.124 0.093 0.075
0.247 0.185 0.149
PROTECTION
8.0 9.0 10.0
0.401 0.368 0.345
0.802 0.736 0.689
1.605 1.472 1.378
3.209 2.945 2.756
4.814 4.417 4.134
6.418 5.889 5.513
8.023 7.361 6.891
0.663 0.630 0.603
1.327 1.260 1.207
2.653 2.521 2.414
5.307 5.041 4.827
7.960 7.562 7.241
10.614 10.083 9.654
13.267 12.604 12.068
D E t
r
3.0094 0.7222 5.67
-0.2840 4.0505 3.88
-4.1899 9.1272 5.95
-0.0800 0.1271 1.08
8.0 9.0 10.0
0.063 0.055 0.049
0.126 0.110 0.098
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