Installation manual

Application Parameters
88 S1A53838 09/2011
DC Injection Braking Parameters
The drive can inject DC current into the motor to apply braking torque to the load. Parameters [DC brake start
freq.] (F250), [DC braking current] (F251) and [DC braking time] (F252) determine the Output Starting
Frequency, current level, and braking time.
During DC injection braking, the drive’s switching frequency is 6 kHz regardless of the setting of parameter
[Switch. freq. level] (F300) (see page 85).
0
0
DC brake start freq.
ON
OFF
Time (s)
Speed Reference
Run Command
DC Braking
Output Frequency (Hz)
DC Braking Current
DC braking
time
Output Current
(A)
Code Name / Description Adjustment range Factory setting
F250 [DC brake start freq.]
0.0 to [Max frequency] (FH) Hz 0.0 Hz
WARNING
NO HOLDING TORQUE
z DC injection braking does not provide holding torque at zero speed.
z DC injection braking does not work when there is a loss of power or when the drive detects a fault.
z When necessary, use a separate brake to maintain torque levels.
Failure to follow these instructions can result in death, serious injury, or equipment damage.
When stopping the motor, the drive will apply DC injection braking once the output frequency drops below the level set
by parameter
F250.
F251 [DC braking current]
DC braking current level
0 to 100% 50% (1)
CAUTION
RISK OF DAMAGE TO THE MOTOR
Check that the motor will withstand this current without overheating.
Failure to follow this instruction can result in equipment damage.
Parameter F251 sets the level of current applied to the motor during DC injection braking. The displayed value, percent or
amperes, is set by parameter [Unit value selection] (F701) (see page 120
).
During DC injection braking, the drive’s overload protection sensitivity increases. The drive automatically lowers the applied DC
current to avoid an overload detected fault.
F252 [DC braking time]
0.0 to 20.0 s 1.0 s
CAUTION
RISK OF DAMAGE TO THE MOTOR
z Long periods of DC injection braking can cause overheating and damage the motor.
z Protect the motor by avoiding long periods of DC injection braking.
Failure to follow this instruction can result in equipment damage.
Parameter F252 determines how long DC injection braking is applied to the motor.
(1) Percentage of the drive's rated current or ampere range. This will vary according to drive power rating.