8400 motec | Software Manual
Motor control (MCTRL)
V/f characteristic control (VFCplus)
66 L Firmware ≤ 02.00 - DMS 2.1 EN - 03/2011
5.5 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 use 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 ≤ f ≤ 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
.
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)
( 103)
To Next Page
Loading...
