Motor Electronic Overload Protection - WEG SSW-08 Manual Del Usuario

Setting the SSW-08

4.8 MOTOR ELECTRONIC OVERLOAD PROTECTION

The motor electronic overload protection simulates the heating and cooling of the motor, also
known as thermal image. This simulation uses as input data the True rms current.
When the thermal image passes the limit, the overload protection trips and turns the motor off.
The adjustment of the thermal class is based on the motor locked rotor current and locked rotor
time. With this data it is possible to find a point in the figure to determine, which thermal class
protects the motor. Please refer to figure 4.8 for cold stall time or to figure 4.9 for hot stall time.
The thermal classes below the point protect the motor.
4
30 | SSW-8
Time t(s)
10000
1000
100
10
1
S.F.=1 1x 2x 3x 4x
S.F.=1,15 1x 2x 3x 4x 5x 6x 7x 8x 9x 10x
Figure 4.8: Thermal classes of motor protection in cold condition
5x 6x 7x 8x 9x
Class 30
Class 25
Class 20
Class 15
Class 10
Class 5
x In motor
current