Q9 ASD Installation and Operation Manual 99
DC Injection Braking Start Frequency
Program Special Controls
During deceleration this is the frequency at which DC Injection braking will
start.
DC Injection Braking
DC Injection Braking is a braking system used with three-phase motors. Unlike
conventional brakes, there is no physical contact between the rotating shaft and a
stationary brake pad or drum. When braking is required, the ASD outputs a DC
current that is applied to the windings of the motor to quickly brake the motor.
The braking current is discontinued when the time entered in F252 times out.
The intensity of the DC current used while braking determines how fast the motor
will come to a stop and may be set at F251. The intensity setting is entered as a
percentage of the full load current of the ASD.
DC Injection Braking is also used to preheat the motor or to keep the rotor from
spinning freely when the motor is off by providing a pulsating DC current into the
motor at the Carrier Frequency (Zero Speed). This feature may be enabled at
F254.
Direct Access Number — F250
Parameter Type — Numerical
Factory Default — 0.00
Changeable During Run — Yes
Minimum — 0.00
Maximum — 120.00
Units — Hz
DC Injection Braking Current
Program Special Controls
This parameter sets the percentage of the rated current of the ASD that will be
used for DC Injection braking. A larger load will require a higher setting.
Direct Access Number — F251
Parameter Type — Numerical
Factory Default — 50
Changeable During Run — Yes
Minimum — 0
Maximum — 100
Units — %
DC Injection Braking Time
Program Special Controls
This parameter setting is used to set the on-time duration of the DC Injection
Braking.
Direct Access Number — F252
Parameter Type — Numerical
Factory Default — 1.0
Changeable During Run — Yes
Minimum — 0.0
Maximum — 20.0
Units — Seconds
DC Injection On During Direction Change
Program Special Controls
This parameter setting determines if DC Injection braking is to be used during a
change in the direction of the motor.
Settings:
0 — Disabled
1 — Enabled
Direct Access Number — F253
Parameter Type — Selection List
Factory Default — Disabled
Changeable During Run — Yes
F250 F253
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