146 Program featuresTorque control performance figuresThe drive can perform precise torque control without any speed feedback from themotor shaft. The table below shows typical performance figures for torque control.Scalar controlIt is possible to select scalar control as the motor control method instead of vectorcontrol. In the scalar control mode, the drive is controlled with a frequency reference.It is recommended to activate the scalar control mode in the following specialapplications:• In multimotor drives: 1) if the load is not equally shared between the motors,2) if the motors are of different sizes, or 3) if the motors are going to be changedafter the motor identification.• If the nominal motor current is less than 20% of the nominal output current of thedrive.• When the drive is used for test purposes with no motor connected.The scalar control mode is not recommended for permanent magnet synchronousmotors.In the scalar control mode, some standard features are not available. SettingsParameter 9904 MOTOR CTRL MODEt (s)TN = rated motor torqueTref = torque referenceTact = actual torqueTorquecontrolNo pulseencoderWith pulseencoderNon-linearity ± 5% withnominaltorque(± 20% at themostdemandingoperatingpoint)± 5% withnominaltorqueTorque steprise time< 10 ms withnominaltorque< 10 ms withnominaltorque100< 5 ms9010TrefTactTTN(%)
