114 Program featuresSettings• Menu - Primary settings - Motor - U/f ratio• Parameter 97.20 U/F ratio (page 335). Flux brakingThe drive can provide greater deceleration by raising the level of magnetization in themotor. By increasing the motor flux, the energy generated by the motor duringbraking can be converted to motor thermal energy.The drive monitors the motor status continuously, also during flux braking. Therefore,flux braking can be used both for stopping the motor and for changing the speed. Theother benefits of flux braking are:• The braking starts immediately after a stop command is given. The function doesnot 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 motorincreases during flux braking, not the rotor current. The stator cools much moreefficiently than the rotor.• Flux braking can be used with induction motors and permanent magnetsynchronous motors.Two braking power levels are available:• Moderate braking provides faster deceleration compared to a situation where fluxbraking is disabled. The flux level of the motor is limited to prevent excessiveheating of the motor.• Full braking exploits almost all available current to convert the mechanical brakingenergy to motor thermal energy. Braking time is shorter compared to moderatebraking. In cyclic use, motor heating may be significant.WARNING: The motor needs to be rated to absorb the thermal energygenerated by flux braking.TBr204060(%)MotorspeedNo flux brakingFlux brakingTBr = Braking torque= 100 NmFlux brakingNo flux brakingt (s) f (Hz)
