WEG SSW-08 User Manual - page 46

5

Programming Information and Suggestions

SSW-08 | 41 

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

SSW08

  =  30 A

I

MOTOR

  =  25 A

S. F.  =  1.15

Setting of the Motor Current = I

MOTOR

 x S.F. / I

SSW08

 = 25 A x 1.15 / 30 A = 96%

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.