ABB ACS 800 Series, Firmware Manual

Page: 73 / 340

Program features
73
Scalar control
It is possible to select Scalar control as the motor control method instead of Direct
torque control (DTC). In the Scalar control mode, the drive is controlled with a
frequency reference. The outstanding performance of the default motor control
method, Direct torque control, is not achieved in Scalar control.
It is recommended to activate the Scalar control mode in the following special
applications:
• In multimotor drives: 1) if the load is not equally shared between the motors, 2) if
the motors are of different sizes, or 3) if the motors are going to be changed after
the motor identification
• If the nominal current of the motor is less than 1/6 of the nominal output current of
the drive
• If the drive is used without a motor connected (for example, for test purposes)
• The drive runs a medium voltage motor via a step-up transformer.
In the Scalar control mode, some standard features are not available.
Settings
Parameter 99.04 .
IR compensation for a scalar-controlled drive
IR compensation is active only when the motor
control mode is Scalar (see section
Scalar control
on page 73 . When IR compensation is activated,
the drive gives an extra voltage boost to the
motor at low speeds. IR compensation is useful in
applications that require high breakaway torque.
In Direct torque control, no IR compensation is
possible/needed.
Settings
Parameter 26.03 .
f (Hz)
Motor Voltage
No compensation
IR compensation