Dc Magnetization - ABB ACS380 Firmware Manual

ACS380 FW.book Page 77 Friday, May 4, 2018 4:18 PM
• The braking starts immediately after a stop command is given. The function does
not need to wait for the flux reduction before it can start the braking.
• The cooling of the induction motor is efficient. The stator current of the motor
increases during flux braking, not the rotor current. The stator cools much more
efficiently than the rotor.
• Flux braking can be used with induction motors and permanent magnet motors.
Two braking power levels are available:
• Moderate braking provides faster deceleration compared to a situation where flux
braking is disabled. The flux level of the motor is limited to prevent excessive
heating of the motor.
• Full braking exploits almost all available current to convert the mechanical braking
energy to motor thermal energy. Braking time is shorter compared to moderate
braking. In cyclic use, motor heating may be significant.
WARNING: The motor needs to be rated to absorb the thermal energy
generated by flux braking.
Settings
Parameter 97.05 Flux braking


DC magnetization

The drive has different magnetization functions for different phases of motor
start/rotation/stop: pre-magnetization, DC hold, post-magnetization and pre-heating
(motor heating).
Pre-magnetization
Pre-magnetization refers to DC magnetization of the motor before start. Depending
on the selected start mode (vector or scalar) 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, it is possible to synchronize the
motor start and, for example, the release of a mechanical brake.
Settings
Parameters 21.01 Vector start mode
and 21.02 Magnetization time
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. When both the reference
and motor speed drop below a certain level, the drive will stop generating sinusoidal
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(page 341).
(page 169), 21.19 Scalar start mode
(page 170).
Program features 77
(page 175)