Machine Protection6- 51Setting Torque Limits Using Constants and an Analog InputThe following block diagram shows the relationship between torque limit using constants and torque limitusing an analog input.The lowest torque limit set from among the following is enabled: Torque limit using constants, torque limitusing an analog input, 150% of Inverter rating (when set to CT), or 120% of Inverter rating (when set to VT)set in C6-01.Fig 6.37 Torque Limit Using Constants and an Analog InputSelecting the Control Method for Torque Limit during Acceleration and Deceleration(SPEC: E or later only)L7-07 is used to select the control method for the torque limit during acceleration and deceleration. The selec-tions are proportional control and integral control. For applications, in which the torque limit will be reachedduring acceleration and deceleration, torque control can be given priority by selecting integral control. Toincrease the change in frequency for the torque limit when integral control is selected, decrease the value setfor L7-06 (Integral Time Setting for Torque Limit).Setting Precautions• When the torque limit function is operating, control and compensation of the motor speed is disabledbecause torque control is given priority. Therefore, the acceleration and deceleration times may increase orthe number of motor rotations may decrease.• When using the torque limit to raise and lower loads, do not carelessly lower the torque limit value, as thismay result in the motor falling or slipping.• Torque limits using an analog input are the upper limit value (during 10 V or 20 mA input) of 100% of themotor rated torque. To make the torque limit value during 10 V or 20 mA input 150% of the rated torque,set the input terminal gain to 150.0 (%). Adjust the gain for multi-function analog input terminal A2 usingH3-10• The torque limit accuracy is ±5% at the output frequency of 10 Hz or above. When output frequency is lessthan 10 Hz, accuracy is lowered.• When the torque is limited while L7-07 is set to 1 (integral control), the acceleration and decelerationtimes may increase or the motor speed may not agree with the speed reference value.Multi-function analog inputTerminalA2 or A3 Forward torque limit(set value = 10)Negative torque limit(set value = 11)Regenerative torque limit(set value = 12)Positive/negative torque limit(set value = 15)Positive forward drivetorque Reverse positive regenerative torqueForward negative regenerative torqueReversedrivereversetorqueMin: Minimum value priority circuitConstantsForward torque limit(L7-01)Reverse torque limit(L7-02)Forward regenerative torquelimit (L7-03)Reverse regenerative torquelimit (L7-04) 150% (when set to CT) or 120% (when setto VT) of Inverter rated currentForward torque limitReverse torque limitForward regenerativetorque limitReverse regenerativetorque limitor A3and for multi-function analog input terminal A3 using H3-06.
