Lenze 8400 - Manual (Page 148)

5 Motor control (MCTRL)
5.4 V/f characteristic control (VFCplus)
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Lenze · 8400 protec HighLine · Reference manual · DMS 3.0 EN · 03/2013 · TD05
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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 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 your pump drive or fan drive is not suitable for operation with a quadratic V/f
characteristic, you must either use the V/f characteristic control function with a
linear V/f characteristic or the sensorless vector control (SLVC).
• 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 the quadratic V/f characteristic, we recommend to set a lower V
min
.
• 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) ( 249)