Commissioning
5-12
820XBA1097
3. Set the Vmin boost
(C016).
Load-dependentboost of the motor voltage in the field-frequency range below the
V/f-rated frequency. C016 acts as gain factor of the auto-boost function.
Adjustment
In general, an adjustment is not necessary. An optimisation can be advantageous:
For drives with very high starting torques:
A Operate the motor under load.
B Select the frequency setpoint.
C Increase V
min
until the required motor current (torque) occurs.
Too high settings of V
min
can lead to a positive-feedback effect which activates the
TRIP ”Overcurrent” (OCx).
For drives with square load torques (fans, pumps):
A Operate the motor under load.
B Select the frequency setpoint.
C Adapt V
min
until the motor is running steadily and smoothly over the whole fre-
quency range.
Too high settings of V
min
can activate the TRIP ”Overcurrent” (OCx) and lead to an
extensive motor temperature.
For drives with special motors:
A Operate the motor under load.
B Select the frequency setpoint.
C Increase V
min
until the required motor current (torque) occurs.
Too high settings of V
min
can lead to a positive-feedback effect which activates the
TRIP ”Overcurrent” (OCx).
D Check the current consumption during idle-running when no load is applied
4. Set slip compensation
(C021).
Rough setting by means of the motor data:
4. Set slip compensation
(C021).
s
n
rsyn
n
r
n
rsyn
ô
100%
n
rsyn
f
dr
ô
60
p
s
Slip constant (C021)
n
rsyn
synchronous motor speed [min
-1
]
n
r
rated speed to motor nameplate [min
-1
]
f
dr
rated frequency to motor nameplate [Hz]
p
Number of pole pairs
Precise setting:
Change C021 under constant load until the speed is near the synchronous speed.
If C021 is set to too high values, the drive may become instable (overcompensation).
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