Chapter 6 – Parameters
6-24
ACH 500 Programming Manual
AUTOMATIC
The motor voltage is automatically controlled to minimize the motor losses
and noise. This setting is suitable for a motor which has a slowly changing
load torque and which operates mainly below nominal load. This feature
should not be used with undersized motors (motor hp below drive rated hp).
Note: If Parameter 20.4.3 (V/Hz Ratio) is set to
SQUARED
or
AUTOMATIC
,
Parameter 20.4.5 (IR Compensation) must be set to
NO
.
4 FIELD WEAK POINT
The Field Weakening Point is the frequency where the output voltage reaches
the maximum output voltage. Above this frequency, the voltage remains at the
maximum motor voltage value.
Figure 6-7 shows various field weakening points.
Figure 6-7 Field Weakening Points
Figure 6-8 shows Parameters 20.4.2 and 20.4.4 adjusted to run a motor not of
rated voltage.
Figure 6-8 Motor Not of Rated Voltage
Field Weakening Points
f [Hz]
60 Hz
Constant Torque
Field Weak. Area
V
V
MAX
f [Hz]
60
480
V
MAX
380
50
90
[V]