sepam 20 user manual - Schneider Electric

Protection functions Negative sequence / unbalance
ANSI code 46
Determination of tripping time for
different negative sequence current
values for a given curve
Use the table to find the value of K that corresponds to
the required negative sequence current. The tripping
time is equal to KT.
Example
given a tripping curve with the setting T = 0.5 s.
What is the tripping time at 0.6 Ib?
Use the table to find the value of K that corresponds to
60 % of Ib.
The table reads K = 7.55. The tripping time is equal to:
0.5 x 7.55 = 3.755 s.
PCRED301005EN - 06/2008
MT10546
IDMT tripping curve
li (% lb) 10 15 20 25 30 33.33 35 40 45 50 55 57.7 60 65 70 75
K 99.95 54.50 35.44 25.38 19.32 16.51 15.34 12.56 10.53 9.00 8.21 7.84 7.55 7.00 6.52 6.11
li (% lb) cont’d 80 85 90 95 100 110 120 130 140 150 160 170 180 190 200 210
K cont’d 5.74 5.42 5.13 4.87 4.64 4.24 3.90 3.61 3.37 3.15 2.96 2.80 2.65 2.52 2.40 2.29
li (% lb) cont’d 22. 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370
K cont’d 2.14 2.10 2.01 1.94 1.86 1.80 1.74 1.68 1.627 1.577 1.53 1.485 1.444 1.404 1.367 1.332
li (% lb) cont’d 380 390 400 410 420 430 440 450 460 470 480 490 u 500
K cont’d 1.298 1.267 1.236 1.18 1.167 1.154 1.13 1.105 1.082 1.06 1.04 1.02 1
t(s)
10000
5000
2000
1000
500
200
100
50
20
10
5
2
1
0.5
0.2
0,1
0.05
0.02
0.01
0.005
0.002
0.001
min. curve (T=0,1s)
max. curve (T=1s)
0.05 0.1 0.2 0.3 0.5 0.7 1 2 3 5 7 10 20
3/11
I/Ib
3