ABB ACS880-x04, Firmware Manual

Page: 63 / 604

Program features 63

DC magnetization
DC magnetization can be applied to the motor to
• heat the motor to remove or prevent condensation, or
• to lock the rotor at, or near, zero speed.
Pre-heating
A motor pre-heating function is available to prevent condensation in a stopped motor,
or to remove condensation from the motor before start. Pre-heating involves feeding
a DC current into the motor to heat up the windings.
Pre-heating is deactivated at start, or when one of the other DC magnetization
functions is activated. With the drive stopped, pre-heating is disabled by the safe
torque off function, a drive fault state, or the process PID sleep function. Pre-heating
can only start after one minute has elapsed from stopping the drive.
A digital source to control pre-heating is selected by parameter 21.14 Pre-heating
input source . The heating current is set by 21.16 Pre-heating current .
Pre-magnetization
Pre-magnetization refers to DC magnetization of the motor before start. Depending
on the selected start mode (
21.01 Start mode or 21.19 Scalar start mode ), pre-
magnetization can be applied to guarantee the highest possible breakaway torque,
up to 200% of the nominal torque of the motor. By adjusting the pre-magnetization
time (
21.02 Magnetization time ), it is possible to synchronize the motor start and, for
example, the release of a mechanical brake.
DC hold
The function makes it possible to lock the rotor at (near) zero speed in the middle of
normal operation. DC hold is activated by parameter
21.08 DC current control . When
both the reference and motor speed drop below a certain level (parameter 21.09 DC
hold speed ), the drive will stop generating sinusoidal current and start to inject DC
into the motor. The current is set by parameter 21.10 DC current reference . When the
reference exceeds parameter 21.09 DC hold speed , normal drive operation
continues.