Lenze 8400 - VF Characteristic Control (Vfcplus)

Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23 157
5 Motor control (MCTRL)
5.4 V/f characteristic control (VFCplus)
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5.4 V/f characteristic control (VFCplus)
In case of the V/f characteristic control (VFCplus), the motor voltage of the inverter is determined by
means of a linear or quadratic characteristic depending on the field frequency or motor speed to be
generated. The voltage follows a preselected characteristic.
 Stop!
• The V/f characteristic control is only suitable for asynchronous motors.
• The following must be observed when operating drives with quadratic V/f
characteristic:
• Please always check whether the corresponding drive is suitable for operation with
a quadratic V/f characteristic!
• If you pump or fan drive is not suitable for operation with a square-law V/f
characteristic, we recommend using the energy-saving V/f characteristic control
(VFCplusEco). Alternatively, you can use the V/f characteristic control with linear
V/f characteristic or the sensorless vector control (SLVC) or servo control (SC).
• For adjustment, observe the thermal performance of the connected asynchronous
motor at low output frequencies.
• Usually, standard asynchronous motors with insulation class B can be operated for
a short time with their rated current in the frequency range 0 Hz ... 25 Hz.
• Contact the motor manufacturer to get the exact setting values for the max.
permissible motor current of self-ventilated motors in the lower speed range.
• If you select square-law V/f characteristics, we recommend setting a lower V
min
or
using the energy-saving V/f characteristic control (VFCplusEco).
• The nameplate data of the motor (at least rated speed and rated frequency) must be
entered if, instead of a standard motor, an asynchronous motor is used with the
following values:
•rated frequency ≠ 50 Hz (star) or
•rated frequency ≠ 87 Hz (delta) or
• number of pole pairs ≠ 2
 Note!
When the auto DCB threshold (C00019) is set > 0 rpm, there is no torque at the motor
shaft in the lower speed range!
Automatic DC-injection braking (Auto-DCB)
( 268)