Section 1
General Information
Programming & Operation 4-17
MN715
Table 4-1 Parameter Block Definitions Level 1
- Continued
Block Title
Parameters
Description
V/Hz and Boost
CTRL Base FREQ
Torque Boost
Dynamic Boost
Slip Comp
Adjustment
V/Hz Profile
V/Hz 3-PT Volts
V/Hz 3-PT
Frequency
Max Output Volts
Represents the point on the V/Hz profile where output voltage becomes constant with
increasing output frequency. This is the point at which the motor changes from
constant or variable torque to constant horsepower operation. In some cases the
Max Output Volts and CTRL Base Freq values can be manipulated to provide a wider
constant torque or wider constant horsepower speed range than is normally available
with the motor.
Adjusts the amount of motor starting torque. The boost adjustment alters the output
voltage to the motor from the normal voltage value by increasing or decreasing the
starting voltage by fixed values as defined by the V/Hz profile. The factory setting is
suitable for most applications. Increasing the boost may cause the motor to overheat.
If adjustment is required, increase the boost in small increments until the motor shaft
just starts to rotate with maximum load applied.
The Dynamic Boost parameter can be adjusted to provide more or less running torque
from the motor than is available with the factory setting. The boost adjustment alters
the output voltage to the motor from the normal voltage value by increasing or
decreasing the voltage per frequency unit as defined by the V/Hz profile.
Compensates for varying load conditions during normal operation. This parameter sets
the maximum allowable variation in output frequency under varying load conditions
(changes of output current). As motor current increases toward 100% of Motor Rated
Amps, output frequency is automatically increased to compensate for slip.
Sets the Volts/Frequency ratio of the control output (to the motor) for all values of output
voltage versus output frequency up to the control base frequency. Because motor
voltage is related to motor current, motor voltage can then be related to motor torque.
A change in the V/Hz profile can adjust how much torque is available from the motor
at various speeds.
3PT profile - allows two linear V/Hz segments by setting the V/Hz 3PT Volts and V/Hz
3PT Frequency parameters. 33%, 67% and 100% Square Law profiles are preset
profiles that provide different variations of the squared reduced V/Hz profile.
These profiles are shown in Figure 4-3.
The output voltage associated with the 3PT Frequency parameter.
The output frequency associated with the 3PT Volts parameter.
The maximum output voltage available to the motor from the control. This is useful if the
motor rated voltage is less than the input line voltage. In some cases the Max Output
Volts and the CTRL Base Frequency parameter values can be adjusted to provide a
wider constant torque or wider constant horsepower speed range than is normally
available.
LEVEL 2 BLOCK
ENTERS LEVEL 2 MENU
Figure 4-3 Volts/Hertz Profile
Max Output
Torque Boost
Output
V
olts
Output Frequency
Base
Freq.
3 PT
Volts
Max Output
Torque Boost
Output
V
olts
Output Frequency
Base
Freq.
Linear V/Hz Curve
3 Point V/Hz Curve
Square Law V/Hz Curve
Max Output
Torque Boost
Output
V
olts
Output Frequency
Base
Freq.
3 PT Freq.
3 PT Volts
33% Square Law
67% Square Law
100% Square Law
