Service Factor - WEG SSW-08 Manual Del Usuario

Motor + load starting data:
Starting by Voltage Ramp, starting current average:
3 x the nominal current of the motor during 17 s (3 x ln @ 17 s).
1) In the graph, figure 4.8 in cold condition, one can see the minimum Thermal Class that will
allow the start with a reduced voltage:
For 3 x ln of the motor @17 s, the next highest is adopted: Class 10.
2) In the graph, figure 4.9 in hot condition, one can see the maximum Thermal Class that the
motor can stand due to the stall time in hot condition:
For 6.6 x ln of the motor @ 12 s, the next lowest is adopted. Class 30.
One now knows that Thermal Class 10 allows a start and Thermal Class 30 is the maximum
limit. Thus, a Thermal Class between the two should be adopted, according to the quantity of
starts per hour and the interval of time between Off/On procedures the motor.
The closer to Class 10, the more protected the motor will be, the fewer the starts per hour and
the greater the interval of time must be between Off/On procedures the motor.
The closer to Class 30, the closer it gets to the maximum limit of the motor, thus there can be
more starts per hour and lower intervals of time between Off/On procedures the motor.

5.2.2 Service Factor

When the Service Factor (S.F.) is different from 1.00 and if there is the need to use it in the
application, this must be considered in the setting of the overload protection. To avoid tripping
of the overload protection, when the service factor is used, the nominal motor current set at the
SSW08 must be readjusted. If an acessorie with parameter access is used, the service factor
can be set direcly in the P406, avoiding the readjustment of the nominal currrent.
Example of readjustment of the nominal current:
I = 30 A
SSW08
I = 25 A
MOTOR
S. F. = 1.15
Setting of the Motor Current = I
ATTENTION!
The increased motor current has direct impact on the maximum thermal class, that
protects the motor, even if the S.F. parameter is set.
Programming Information and Suggestions
x S.F. / I = 25 A x 1.15 / 30 A = 96%
MOTOR SSW08
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