Frequency Inverter DF51... - Moeller.com.tr

04/07 AWB8230-1541GB Motor controlMotor controlU/f characteristicPNU Designation RUN b031= 10Value Function DSA044U/fcharacteristic– – By default, the DF51 uses a linear U/f characteristicUb[%] 100(constant torque curve) to accelerate and brake theamotor.000c linear, b square-lawf00 Constant torque curve01 Reduced torque curveWith a linear U/f characteristic the ratio of output voltage tooutput frequency remains linear in the range from 0 Hz to therated frequency (PNU A003, a page 68) a constant torquecurve. This facilitates constant load torques also duringacceleration and deceleration.In the range from the motor’s rated frequency (PNU A003) up tothe manufacturer’s specified maximum frequency (speed,PNU A004 a page 68), the output voltage remains constant asthe frequency increases.If you select the square-law torque curve, the U/f ratio changes ina square-law pattern. This results in a reduced starting torque inthe lower frequency/speed range.Examples:a Linear U/f characteristic:• for parallel operation of several motors at the frequencyinverter’s output.• for changeovers at the frequency inverter’s output.• when operating motors with a low rating.• Application requiring a reduced starting torque.U 100[%]0A003A004f 1 f 2Figure 68: PNU A044 = 01, square-law torque characteristicf 1 : Transition frequency, motor rated frequency (H004)f 2 : End frequency, highest permissible motor frequencyf [Hz]U[%]100A003A0040f 1 f 2f [Hz]Figure 67: PNU A044 = 00, constant torque characteristicf 1 : Transition frequency, motor rated frequency (H004)f 2 : End frequency, highest permissible motor frequencyb Quadratic U/f characteristic:• Energy-optimized operation of pumps, fans, etc.67