98 Program featuresThe function is also available for scalar motor control with a frequency reference. Theinput of the function is shown by 28.96 Frequency ref act 7.ExampleA fan has vibrations in the range of 540 to 690 rpm and 1380 to 1560 rpm. To makethe drive avoid these speed ranges,• enable the critical speeds function by turning on bit 0 of parameter 22.51 Criticalspeed function, and• set the critical speed ranges as in the figure below.Settings• Critical speeds: parameters 22.51…22.57 (page 197)• Critical frequencies: parameters 28.51…28.57 (page 219). Rush controlIn torque control, the motor could potentially rush if the load were suddenly lost. Thecontrol program has a rush control function that decreases the torque reference540690138015601 Par. 22.52 = 540 rpm2 Par. 22.53 = 690 rpm3 Par. 22.54 = 1380 rpm4 Par. 22.55 = 1560 rpm1 2 3 422.01 Speed ref unlimited (rpm)(output of function)22.87 Speed reference act 7 (rpm)(input of function)
