102
•
vacon parameter descriptions
9
1.15 T
ORQUE
BOOST
When this parameter has been activated, the voltage to the motor changes au-
tomatically with high load torque which makes the motor produce sufficient
torque to start and run at low frequencies. The voltage increase depends on
the motor type and power. Automatic torque boost can be used in applications
with high load torque, e.g. in conveyors.
0 = Disabled
1 = Enabled
Note: In high torque - low speed applications - it is likely that the motor will
overheat. If the motor has to run a prolonged time under these conditions,
special attention must be paid to cooling the motor. Use external cooling for
the motor if the temperature tends to rise too high.
Note: The best performance can be reached by running motor identification,
see
par. 1.18.
1.16 S
WITCHING
FREQUENCY
Motor noise can be minimised using a high switching frequency. Increasing
the switching frequency reduces the capacity of the frequency converter unit.
Switching frequency for Vacon 20: 1.5…16 kHz.
1.17 B
RAKE
CHOPPER
Note! An internal brake chopper is installed in three phase supply MI2 and MI3
size drives.
0 = Disable (No brake chopper used)
1 = Enable: Always (Used in Run and Stop state)
2 = Enable: Run state (Brake chopper used in Run state)
W
HEN
THE
FREQUENCY
CONVERTER
IS
DECELERATING
THE
MOTOR
,
THE
ENERGY
STORED
TO
THE
INERTIA
OF
THE
MOTOR
AND
THE
LOAD
ARE
FED
INTO
AN
EX
-
TERNAL
BRAKE
RESISTOR
,
IF
THE
BRAKE
CHOPPER
HAS
BEEN
ACTIVATED
. T
HIS
ENABLES
THE
FREQUENCY
CONVERTER
TO
DECELERATE
THE
LOAD
WITH
A
TORQUE
EQUAL
TO
THAT
OF
ACCELERATION
(
PROVIDED
THAT
THE
CORRECT
BRAKE
RESISTOR
HAS
BEEN
SELECTED
). S
EE
SEPARATE
B
RAKE
RESISTOR
IN
-
STALLATION
MANUAL
.
1.19 M
OTOR
IDENTIFICATION
0 = Not active
1 = Standstill identification
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