WEG SSW-07 - Page 34

CHAPTER 4 - SETTING THE SSW-07
33
English
Time t(s)
1000
100
10
1
1x 2x 3x 4x 5x 6x 7x 8x 9x S.F.=1
Class 30
Class 25
Class 20
Class 15
Class 10
Class 5
x In motor
Current
0.1
Figure 4.9 - Motor protection thermal classes in hot condition at 100 % ln
Motor
Current
Class
30 20 10
3xIn 34.4 s 23.6 s 11.8 s
5xIn 12.6 s 8.4 s 4.2 s
7xIn 6.4 s 4.2 s 2.1 s
Table 4.3 - Motor protection thermal class time in hot condition
Currentin%
of In of the motor
Factor
0%(coldcondition) 1
20% 0.87
40% 0.74
60% 0.61
80% 0.48
100%(ratedload) 0.35
Table 4.4 - Multiplication factor of the thermal class times in cold condition to
obtain the thermal class times in hot condition