Hitachi SJ7002 Series Instruction Manual page 101

3–18
"A" Group: Standard Functions
Func.
Code Description
A344 V/f characteristic curve
selection, 3rd motor
Torque control modes
A045 V/f gain setting
Sets voltage gain of the inverter
A046 Automatic torque boost voltage gain
Voltage compensation gain for automatic torque boost
A246 Automatic torque boost voltage gain, 2nd motor
Voltage compensation gain for automatic torque boost
A047 Automatic torque boost slip gain
Slip compensation gain for automatic torque boost
A247 Automatic torque boost slip gain, 2nd motor
Slip compensation gain for automatic torque boost
DC Braking
Settings
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Keypad
Name/
SRW
VC
VP
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
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.
Range and Settings
OPE
00
V/f constant torque
0 1
V/f variable torque
0. to 255.
0. to 255.
0. to 255.
0. to 255.
0. to 255.
Output
voltage
+
Running
0
–
Output
voltage
+
DC braking
A057
0
A058
–
"Acceleration Pause Function" on page
Defaults
Run
Mode
FEF2 FUF2 FF2
Edit
FE2 FU2 F2
Lo Hi
(EU) (USA) (Jpn)
✘ ✘
00 00 00
✔ ✔
100. 100. 100.
✔ ✔
100. 100. 100.
✔ ✔
100. 100. 100.
✔ ✔
100. 100. 100.
✔ ✔
100. 100. 100.
Free run DC braking
A054
t
A053 A055
Running
t
3–21.