WEG SSW-08 Manual Del Usuario página 45

Programming Information and Suggestions
Determine the maximum thermal class:
To correctly program the Thermal Class that will protect your motor it is essential to have in hand
the motor locked rotor current and locked rotor time. This information is available in the motor
manufacturer's catalogue. Put these values into figure 4.8, in case of the cold stall time or into
figure 4.9, in case of hot stall time.
For example:
Stall Current = 6,6 x ln
Hot Stall Time = 6s
5
Class 25 is the highest class that protects the motor.
NOTE!
Remember that this protection has as a standard the Three Phase IP55 Standard
WEG Motor, therefore if your motor is different, then do not program the thermal class
to its maximum, instead, program it near its minimum thermal class to start.
Example of how setting the thermal class:
Motor data:
Power: 50 hp
Voltage: 380 V
Nominal Current (ln): 71 A
Service Factor (S.F.): 1.00
lp/ln: 6.6
Stall time: 12 s in hot condition
Speed: 1770 rpm
40 | SSW-08
t(s)
6 s
0
Figure 5.11: Checking the maximum class of curves in hot condition
Hot
6.6 x ln of the motor
30
25
20
xln