WEG SSW-07 - Page 41

CHAPTER 5 - PROGRAMMING INFORMATION AND SUGGESTIONS
40
English
Therefore the minimum class necessary to start the motor is Class
10. Class 5 has an inferior time for this current.
This class allows motor starting in cold condition.
4) In order to identify the thermal class to start a hot motor, it is
necessary to know the locked rotor time that the motor withstand.
NOTE!
To correctly program the Thermal Class that will protect your motor
it is essential to have in hands the stall time of the motor. This
information is available in the motor manufacturer’s catalogue.
Withthestalltimeitispossibletondthemaximumthermalclass
that will protect the motor to start in hot condition. In the item 4.8
Overload Protection, it is possible to check the thermal class curves
of the motor in hot condition.
Forexample:6.6xln@6s.
6.6 x In of the motor
t(s)
6 s
0
xln
30
Hot
25
20
Figure 5.7 - Checking the maximum class of curves in hot condition
Class 25 is the highest thermal class that protects the motor and
allows its hot start, or in any other condition.
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.