“A” Group: Standard Functions
Configur
ing Dr
iv
e
P
a
ra
meters
3–18
DC Braking
Settings
The DC braking feature can provide additional stopping torque when compared to a normal
deceleration to a stop. It can also ensure the motor and load are stopped before acceleration.
When decelerating
– DC braking is
particularly useful at low speeds when
normal deceleration torque is minimal.
During deceleration, the inverter injects
a DC voltage into the motor windings
during deceleration below a frequency
you can specify (A052). The braking
power (A054) and duration (A055) can
both be set. You can optionally specify a
wait time before DC braking (A053),
during which the motor will free run
(coast).
When starting
– You can also apply
DC braking upon the application of a
Run command, specifying both the DC
braking force level (A057) and the
duration (A058). This will serve to stop
the rotation of the motor and the load,
when the load is capable of driving the
motor. This effect, sometimes called
“windmilling,” is common in fan appli-
cations. Often, air moving in duct work
will drive the fan in a backward direc-
tion. If an inverter is started into such a backward-rotating load, over-current trips can occur.
Use DC braking as an “anti-windmilling” technique to stop the motor and load, and allow a
normal acceleration from a stop. See also the
“Acceleration Pause Function” on page 3–21
.
You can configure the inverter to apply DC braking at stopping only, at starting only, or both.
DC braking power (0–100%) can be set separately for stopping and starting cases.
A344
V/f characteristic curve
selection, 3rd motor
VC
00
V/f constant torque
00
00
00
✘ ✘
Torque control modes
VP
0 1
V/f variable torque
A045
V/f gain setting
0. to 255.
100.
100.
100.
✔ ✔
Sets voltage gain of the inverter
A046
Automatic torque boost voltage gain
0. to 255.
100.
100.
100.
✔ ✔
Voltage compensation gain for automatic torque boost
A246
Automatic torque boost voltage gain, 2nd motor
0. to 255.
100.
100.
100.
✔ ✔
Voltage compensation gain for automatic torque boost
A047
Automatic torque boost slip gain
0. to 255.
100.
100.
100.
✔ ✔
Slip compensation gain for automatic torque boost
A247
Automatic torque boost slip gain, 2nd motor
0. to 255.
100.
100.
100.
✔ ✔
Slip compensation gain for automatic torque boost
Func.
Code
Name/
Description
Keypad
Range and Settings
Defaults
Run
Mode
Edit
Lo Hi
SRW
OPE
FEF2
FE2
(EU)
FUF2
FU2
(USA)
FF2
F2
(Jpn)
DC braking
Free run
Running
Output
voltage
A053
A055
A054
t
+
0
–
DC braking
Running
Output
voltage
A058
A057
t
+
0
–