Lenze DSD - Manual (Page 469)

Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
469
18 Drive dimensioning messages
18.8 Inverters
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18.8.14 The inverter cannot provide the rated output current
18.8.15 VFCplus eco control mode for quasi-stationary drives
18.8.16 Activate VVC control
Warning!
The rated current-inverter ratio to the rated motor current is xxx.
If V/f control is used, the required ratio of yyy is undershot.
For hoist drives with V/f control, drops at max. torque are possible during operation in generator mode and
at low speeds.
Select an inverter that is one power class higher than the motor.
Cause Effects Possible remedies
In this operating mode, the inverter
cannot provide the required current.
The hoist drive cannot hold the load. Select an inverter that is one power
class higher than the motor.
Note!
The VFCplus eco V/f control can only be used for quasi-stationary drives with slow load changes.
Cause Effects Possible remedies
When the VFCplus eco control mode
is used, the machine flux is reduced
in partial load operation. Due to
physical time constants of the ma-
chine, the machine flux cannot be in-
creased abruptly.
If the machine is loaded heavily for a
short time, only a following error
takes place in the best case. In the
worst case, the machine is not braked
safely or stops.
• Use other control modes.
• Magnetise machine in time be-
fore load impulses.
Warning!
Hoist may sag!
Activate the VVC control in the inverter during the commissioning phase if the VFCplus control mode with-
out feedback is used.
Cause Effects Possible remedies
During the dimensioning process of
the inverter (Servo Drive 9400, i700)
and the motor, DSD assumes that the
VVC control (Voltage-Vector-Control)
is activated in the inverter.
• Without VVC control, motor and
inverter must be considerably
overdimensioned when being op-
erated in VFCplus control mode.
Without an activated VVC control,
the hoist may sag.
Activate the VVC control in the in-
verter during the commissioning
phase.