14
Fig.11 tE Protection delay to blocking current ratio IA/Ie Current-time characteristic curve
Instructions:tEp
：
7 times of the rated current allowed lock-in time;IA
：
Locked-rotor current;
Ie
：
Rated current of the motor.
Table10
t
Ep
Set
IA/Ie
2
（
S
）
3
（
S
）
4
（
S
）
5
（
S
）
6
（
S
）
8
（
S
）
10
（
S
）
12
（
S
）
15
（
S
）
2.0
32
48
64
80
96
128
160
192
240
2.2
20.27
30.4
40.54
50.67
60.81
81.08
101.35
121.62
152.02
2.4
14.75
22.12
29.5
36.87
44.25
59
73.75
88.5
110.63
2.6
11.54
17.32
23.09
28.87
34.64
46.19
57.74
69.29
86.62
2.8
9.46
14.19
18.92
23.65
28.39
37.85
43.31
56.78
70.97
3.00
8
12
16
20
24
32
40
48
60
3.20
6.91
10.37
13.83
17.29
20.75
27.67
34.59
41.51
51.88
3.40
6.08
9.13
12.17
15.22
18.26
24.35
30.44
36.52
45.66
3.60
5.43
8.14
10.86
13.58
16.29
21.72
27.16
32.59
40.74
3.80
4.9
7.35
9.8
12.25
14.7
19.6
24.5
29.41
36.76
4.00
4.46
6.69
8.93
11.16
13.39
17.86
22.32
26.79
33.48
4.20
4.09
6.14
8.19
10.24
12.29
16.39
20.49
24.59
30.74
4.40
3.79
5.68
7.58
9.47
11.37
15.06
18.95
22.74
28.42
4.60
3.52
5.28
7.05
8.81
10.57
14.1
17.62
21.15
26.43
4.80
3.29
4.94
6.59
8.24
9.88
13.08
16.48
19.77
24.72
5.00
3.09
4.64
6.19
7.74
9.29
12.38
15.48
18.58
23.22
5.20
2.92
4.38
5.84
7.3
8.76
11.68
14.6
17.53
21.91
5.40
2.76
4.15
5.53
6.91
8.3
11.07
13.83
16.6
20.75
5.60
2.63
3.94
5.26
6.57
7.89
10.52
13.15
15.78
19.73
5.80
2.5
3.76
5.01
6.27
7.52
10.03
12.54
15.05
18.81
6.00
2.4
3.6
4.8
6
7.2
9.6
12
14.4
18
6.20
2.3
3.45
4.6
5.75
6.9
9.2
11.51
13.81
17.26
6.40
2.21
3.32
4.42
5.53
6.64
8.85
11.07
13.28
16.6
6.60
2.13
3.2
4.27
5.33
6.4
8.54
10.67
12.81
16.01
6.80
2.06
3.09
4.12
5.16
6.19
8.25
10.32
12.38
15.48
7.00
2
3
4
5
6
8
10
12
15
8.00
2
3
4
5
6
8
10
12
15
9.00
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0.2
Note
：
（
1
）
The action time of tE protection = the action time /2×t
Ep
when t
Ep
is 2 (S)
（
2
）
When tE is set at 5 (S), the tE value determined according to the starting current ratio IA/ Ie
is in accordance with iEC79-7 and GB3836.3-2000 standards. When it is used for tE time
protection of increased safety motor, its inverse time overload protection can be set according to
this characteristic curve.In order to ensure that the power is disconnected before tE time during the
motor's lock-in, the inverse time curve of the overload protection device should be lowered by
